The Hypothesis Oriented Algorithm II

2003; 83:455-470.PHYS THER. RiddleJules M Rothstein, John L Echternach and Daniel L(HOAC II): A Guide for Patient ManagementThe Hypothesis-Oriented Algorithm for Clinicians II

http://ptjournal.apta.org/content/83/5/455found online at: The online version of this article, along with updated information and services, can be

Collections

Perspectives Diagnosis/Prognosis: Other

Clinical Decision Making in the following collection(s): This article, along with others on similar topics, appears

e-Letters

"Responses" in the online version of this article. "Submit a response" in the right-hand menu under

or click onhere To submit an e-Letter on this article, click

E-mail alerts to receive free e-mail alerts hereSign up

by guest on May 31, 2012http://ptjournal.apta.org/Downloaded from

http://ptjournal.apta.org/cgi/collection/clinical_decision_making

http://ptjournal.apta.org/cgi/collection/diagnosis_prognosis_other

http://ptjournal.apta.org/cgi/collection/perspectives

http://ptjournal.apta.org/letters/submit/ptjournal;83/5/455

http://ptjournal.apta.org/subscriptions/etoc.xhtml

http://ptjournal.apta.org/

The Hypothesis-Oriented Algorithmfor Clinicians II (HOAC II):A Guide for Patient Management

In this era of health care accountability, a need exists for a newdecision-making and documentation guide in physical therapy. Theoriginal Hypothesis-Oriented Algorithm for Clinicians (HOAC) pro-vided clinicians and students with a framework for science-basedclinical practice and focused on the remediation of functional deficitsand how changes in impairments related to these deficits. The HOACII was designed to address shortcomings in the original HOAC and bemore compatible with contemporary practice, including the Guide toPhysical Therapist Practice. Disablement terminology is used in theHOAC II to guide clinicians and students when documenting patientcare and incorporating evidence into practice. The HOAC II, like theHOAC, can be applied to a patient regardless of age or disorder andallows for identification of problems by physical therapists whenpatients are not able to communicate their problems. A feature of theHOAC II that was lacking in the original algorithm is the concept ofprevention and how to justify and document interventions directed atprevention. [Rothstein JM, Echternach JL, Riddle DL. The Hypothesis-Oriented Algorithm for Clinicians II (HOAC II): a guide for patientmanagement. Phys Ther. 2003;83:455–470.]

Key Words: Decision making; Diagnosis; Physical therapy profession, professional issues.

Jules M Rothstein, John L Echternach, Daniel L Riddle

Physical Therapy . Volume 83 . Number 5 . May 2003 455

Pers

pect

ive �

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��



In 1986, Rothstein and Echternach1 published aclinical decision and documentation guide calledthe Hypothesis-Oriented Algorithm for Clinicians(HOAC), which they contended offered clinicians

a pragmatic, scientifically credible approach to patientmanagement. Since that algorithm was first published,radical changes have occurred in the health care system.For example, there is now widespread discussion of theimportance of physical therapists making diagnoses,2and there is also general acceptance of the need to viewpatients and clients within the context of one of thedisability models.3,4 In addition, therapists often have torelate to practice guides and guidelines.5 We argue thatwhat is needed is a patient management system thatinvolves the patient in decision making and can be usedto provide payers with better justifications for interven-tions, including occasions when therapists may disagreewith practice guidelines. Compatibility with the Guide toPhysical Therapist Practice’s (Guide’s) patient manage-ment model, including the formulation of diagnoses, isalso desirable.6

The purpose of this article is to present HOAC II, arevised algorithm designed to meet the needs of con-temporary practice. The algorithm, we believe, is com-patible with the American Physical Therapy Association’s(APTA’s) Guide to Physical Therapist Practice,6 includingthe therapists’ need to diagnose and to offer interven-tions designed to prevent problems. In the context ofthe HOAC II, a problem is almost always a functionaldeficit. Although we attempted to be consistent withGuide terms, there are instances where we used alternateterms for the sake of clarity.

Although the original HOAC was a first effort at bring-ing scientific decision making into a user-friendly prac-tical context for clinical decision making, it has somecumbersome elements as well some logical and proce-dural flaws. The algorithm offered no guidance on howto determine when an intervention designed primarilyfor prevention was appropriate and how risk factorscould be eliminated. The algorithm also did not ade-quately provide a means for identifying problems and

addressing goals noted by someone other than thepatient.

The focus on patient-centered outcomes was, however,an innovation in HOAC and laid a foundation for theimplementation of the HOAC in clinical decision mak-ing in the context of currently used disability models.The disablement model that we believe currently offersthe greatest utility for clinical practice is the Nagimodel.7(pp223–241) A common element in both the oldand new versions of the HOAC is that therapists usingthe terms of the Nagi model are called upon to identifyimpairments, when appropriate; to examine how theseimpairments relate to functional deficits; and to exam-ine whether interventions designed to ameliorate orreduce impairments result in changes in function andchanges in levels of disability. In some cases, therapistsalso can hypothesize that factors other than impairmentsmay lead to functional loss. For example, a societallimitation such as high curbs may contribute to apatient’s inability to walk to school. We also believetherapists have a role in prevention7(pp84–89) and that ina responsibility-focused health care system cliniciansshould identify the hypotheses that underlie interven-tions used for prevention.

We believed that the original HOAC could serve both asa template for documentation and as a conceptualmodel for decision making and, therefore, could linkdocumentation and practice. This does not mean, how-ever, that we believe either the original HOAC or theHOAC II must be implemented in the exact form wehave written it, for all patients, in all settings. Rather, wecontend that elements can be selected based on practi-cality and the expected benefit of using a system inwhich all elements of patient management are explicitlydetailed. The HOAC II, we contend, provides a meansfor not only using evidence in decision making, but alsofor documenting the nature and extent of evidenceused. Within the new version, elements related to justi-

The HOAC II is a revised algorithm

designed to meet the needs of

contemporary practice.

JM Rothstein, PT, PhD, FAPTA, is Professor, Department of Physical Therapy, College of Applied Health Sciences, University of Illinois at Chicago,1919 W Taylor St, 4th Fl, Room 456, Chicago, IL 60612 ([email protected]). Address all correspondence to Dr Rothstein.

JL Echternach, PT, EdD, ECS, FAPTA, is Professor and Eminent Scholar, School of Physical Therapy, Old Dominion University, Norfolk, Va.

DL Riddle, PT, PhD, is Professor, Department of Physical Therapy, Medical College of Virginia Campus, Virginia Commonwealth University,Richmond, Va.

All authors provided concept/idea/project design, writing, and project management. The authors acknowledge the efforts of Andrew Guccione,PT, PhD, FAPTA, Julie Fritz, PT, PhD, ATC, and David Scalzitti, PT, MS, OCS, for reviewing an earlier draft of the manuscript.

This article was submitted March 12, 2002, and was accepted December 2, 2002.

456 . Rothstein et al Physical Therapy . Volume 83 . Number 5 . May 2003 by guest on May 31, 2012http://ptjournal.apta.org/Downloaded from


fication of interventions (eg, where evidence can becited) should be part of any credible system ofdocumentation.

Overview of Elements in HOAC IIIn developing the revised algorithm, we recognized thatthere are usually 2 major types of patient problems:(1) those that exist when the patient is being seen andthat require remediation and (2) those that may occur inthe future and that require prevention. We also realizedthat even though clinicians do not necessarily routinelydiscuss these differences, clinical management of the 2types of problems is different, and assessment of theoutcomes for each must differ.

While there are 2 types of problems (existing andanticipated), there are also 2 ways that problems areidentified. There are patient-identified problems (PIPs)and non–patient-identified problems (NPIPs). Patient-identified problems, which usually consist of functionallimitations and disabilities, often exist when the thera-pist sees the patient. The patient identifies the problem.The therapist, however, needs to generate hypotheses asto the cause of problems and to establish testing criteria,which can be used to evaluate the outcomes of interven-tions, and the correctness of the hypothesis and patientcare strategies. The patient may identify existing prob-lems as well as express concerns relating to problemsthat do not yet exist and could, therefore, be the sourceof an anticipated problem. For example, a patient maycomplain of shoulder pain and express a concern aboutthe development of limitations in movements that couldbe disabling. The limitations in function caused by thepain would be an existing problem (eg, an inability tocook a meal because repetitive use of the shouldercaused intolerable pain). Any loss of function that couldoccur if motion became even more limited would be ananticipated problem.

Non–patient-identified problems are problems that arenot identified by the patient. They are problems thatmay occur as well as existing problems. For example,children may not be able to identify problems secondaryto central nervous system deficits. A child might, forexample, routinely sit in a position that compromises hisor her ability to breath because of decreased thoracicexcursion. The child is unlikely to see this as a problem,but a family member or a member of the health careteam could believe that a problem (NPIP) will develop.In this case, either the therapist or the caregiver will bethe most likely person to identify the problems. Simi-larly, patients who have had a stroke may have difficultycommunicating about their problems, and others willneed to identify these problems. Justification for antici-pated problems, regardless of whether they are PIPs orNPIPs, can, in the HOAC II, only be based on theory or

arguments that are data (evidence) based. Hypothesesthat guide intervention to eliminate existing problems(PIPs or NPIPs) can be tested because a change insomething can be measured (eg, changes in impairmentlevels and disability). Changes in what is measured willbe identified in the part of the algorithm where reassess-ment occurs.

A problem is kept from occurring when anticipatedproblems are correctly managed. Therefore, no observ-able change usually relates directly to the problem. Moreimportantly, in the absence of anything observable ormeasurable, a justification based on an outcome is notpossible for interventions aimed at prevention, becauseeven without intervention a problem may not havearisen.

Testing criteria are used to examine the correctness ofhypotheses related to problems that currently exist. ForNPIPs or PIPs that are anticipated, however, the thera-pist establishes predictive criteria, which, if met, indicatethat problems will most likely be avoided because riskfactors were reduced or eliminated. A predictive crite-rion for a patient with low back pain, for example, maybe that a patient is considered no longer at risk when thepatient can perform stretching exercises at a suitablelevel of performance on a regular basis (the predictivecriteria would detail the specific exercise and how oftenit should be performed).

To justify any predictive criterion, the therapist shouldbase the criterion on best available evidence. Patientswith spinal cord injuries, for example, might no longerbe considered at risk (ie, they have achieved the predic-tive criteria) for developing skin ulcers when they haveshown that: (1) they will spontaneously do wheelchairpushups a given number of times per hour, and (2) theywill monitor the status of their skin by having someonecheck for red marks or abrasions at specified intervals. Ineach case, the predictive criteria relate to an observablebehavior, not just increased awareness or knowledge.The behavior ideally is justified based on identifiedevidence or sound theory and not just on assumptions.Circumstances may make it impossible to achieve goalswith observed behaviors, and in these special circum-stances knowledge may be a reasonable predictive crite-rion (eg, when the therapist cannot visit the patient’sworkplace but teaches the patient strategies for avoidinginjury).

The dual problem lists, one for PIPs and one for NPIPs,are merged into a single problem list as one proceedsthrough the algorithm. Throughout the rest of thealgorithm, the source that identified the problem is nota concern. What is critical, however, is that therapistsmanage anticipated and existing problems differently,

Physical Therapy . Volume 83 . Number 5 . May 2003 Rothstein et al . 457

��

��

��

��

��



and the algorithm provides parallel paths for the man-agement of the 2 types of problems. This is particularlyimportant in the reassessment phase (Part 2 of thealgorithm). The existence of a list of anticipated prob-lems and the predictive criteria allows for the identifica-tion of which interventions are designed for prevention,how these interventions are justified, and when interven-tion can be stopped. A novel element of the HOAC II,one that we believe has not previously been seen inphysical therapy literature, are mechanisms to makeinterventions designed for prevention goal oriented andof determinate duration (ie, there is a stated goal thatmust be achieved and there is an expectation as to howlong this will take).

The algorithm provides clinicians with a mechanism forplanning and evaluating activities designed for preven-tion. This approach encourages therapists to work tominimize risks through prevention, but, more impor-tantly, it allows them to evaluate their efforts and todescribe and justify their efforts to one another, payers,managers, and others. Because in HOAC II preventionactivities are goal driven and are planned for specifiedperiods of time, therapists can, through use of thealgorithm, identify to payers the resources they will needto achieve prevention. This should, in our opinion,assure payers that interventions will not continue indef-initely, unless that can be justified before the initiationof the intervention. The algorithm also allows the ther-apists to document when, in their professional opinions,prevention activities are needed and the consequencesof what will occur if these are not carried out (eg, due toa lack of patient adherence or because they are notauthorized by payers).

In a continued effort to keep focus on what are truly thepatient’s goals, one problem list (the PIP list) is gener-ated before the examination. In the HOAC II, there is arecord, at least initially, of who identified the problem. Acomplete problem list, however, including problemsidentified by the therapist and others, and a complete setof goals are not generated until later in the process.Figures 1 and 2 illustrate Part 1 of the HOAC II.

In Part 2 of the HOAC II, there are 2 reassessment paths,one for existing problems and one for anticipatedproblems (Figs. 3 and 4). In each case, there arequestions on a flow diagram that direct therapiststhrough relatively simple steps that are taken in responseto questions. Two flow diagrams are used to describe thereassessment, one for existing problems and one foranticipated problems. A list of commonly used termsoperationally defined for the HOAC II is provided in theAppendix.

Using the AlgorithmPart 1 of the algorithm deals with all 5 elements of thepatient/client management model described in theAPTA’s Guide to Physical Therapist Practice 6 (examination,evaluation, diagnosis, prognosis, and intervention). TheGuide is not specific about issues related to the use of anevaluative strategy to modify interventions and to testhypotheses. In the Guide, however, under “Interven-tion,” it is stated: “Decisions about intervention arecontingent on the timely monitoring of patient/clientresponse and the progress made toward achieving theanticipated goals and expected outcomes.”6(p46) Webelieve, therefore, that Part 2 of our algorithm is anelaboration on one vital element of what the Guiderefers to as “intervention.” In the HOAC II, issues relatedto monitoring intervention effects and altering the planof care are covered in Part 2.

Part 1

Collect Initial Data (Includes the History)Early in an episode of care, clinicians start to obtaininformation that they will use to guide all elements ofpatient management. Practitioners appear to approacheach patient with a set of hypotheses and collect data toconfirm or refute those hypotheses8,9; therefore, eveninitial data collection is hypothesis driven. During theinterview, for example, questions about activities thatmay have caused an injury are one sign that the clinicianis seeking to confirm or deny hypotheses. More experi-enced clinicians can be expected to generate hypothesesearlier than less experienced practitioners9 and, in ourexperience, more effective clinicians often feel a greaterfreedom to discard hypotheses and consider alternativesas early as the interview phase of the patientexamination.

The algorithm does not specify the type and scope ofinformation gathered during the initial data collectionphase. This remains the choice of clinicians, dependingon their approach to practice. The algorithm simplyrequires clinicians to note what they do in this process.Information that will be used to create a PIPs list needsto be obtained during the initial data collection.

Patients seeking physical therapy have expectations ofwhat therapy should offer them, and these may differfrom what their therapists feels are reasonable. A patientmay believe that walking without an assistive deviceshould be the goal, for example, whereas the therapistmay contend that this would be impossible and walkingwith a device would be a reasonable goal. Among theessential data that clinicians must collect are clear non-medical descriptions of expectations, particularlydescriptions of those disabilities and functional limita-tions that need to be eliminated. Incongruence among



Figure 1.The initial steps of Part 1 of the Hypothesis-Oriented Algorithm for Clinicians II (HOAC II).


��

��

��

��

��



Figure 2.The final steps of Part 1 of the Hypothesis-Oriented Algorithm for Clinicians II (HOAC II).



Figure 3.The algorithm for reassessment of existing problems in Part 2 of the Hypothesis-Oriented Algorithm for Clinicians II (HOAC II).


��

��

��

��

��



Figure 4.The algorithm for reassessment of anticipated problems in Part 2 of the Hypothesis-Oriented Algorithm for Clinicians II (HOAC II).



expectations of the patient, a payer, a referral source,and a therapist will be considered when problem lists aregenerated, but information about the differing expecta-tions needs to be obtained early in the process.

Generate a PIPs ListGenerating the PIPs list is one of the easiest things to doin the HOAC II. It requires clinicians simply to recordpatients’ reports of the problems that led them to seekphysical therapy (or the medical care that led to areferral for physical therapy). Therapists ask patientsabout what they can and cannot do (ie, what limitationsthey have in function). A functional limitation or disabil-ity is a problem, and, in some cases, patients also mayexpress concerns that they have a condition that couldlead to the development of loss of function in the future.In this way, a patient could be the one who identifies ananticipated problem. The therapist, however, with con-sultation with the patient, needs to determine whetherthe patient’s concern is realistic and, if the anticipatedproblem is justified, add it to the problem list.

Because the HOAC II emphasizes accountability, webelieve therapists should never assume that any patientconcern about the future means that an anticipatedproblem will occur. Only when the therapist can supplyevidence or a sound theoretical argument to support thepossibility of the anticipated problem occurring shouldit be placed on the list, which is true regardless of thesource. Evidence is preferred over theory when thetherapist believes that the patient’s concern about futureevents is not warranted. The therapist needs to discussthe reasons with the patient and, to enhance account-ability, document that the discussion took place (ie, ifthe patient’s concern was not added to the problem list,explain why).

Formulate Examination StrategyBased on the initial data collected and the nature of thePIPs, the therapist needs to determine what other infor-mation is needed. This is an examination strategy, and itcannot exist independently of hypotheses. When gener-ating the examination strategy, the therapist is not yetable to identify a best hypothesis as to the cause of thepatients’ problems (both PIPS and NPIPS). The thera-pist may have several competing hypotheses and needsto develop an examination strategy that will obtaininformation to confirm correct hypotheses and negatenonviable hypotheses. Unless a therapist has some ten-tative ideas (hypotheses) as to what may be causing theproblems (eg, the potential impairments or pathologiescausing functional limitations or disabilities), there canbe no examination strategy.

Experienced clinicians appear to generate hypothesesmore readily than less expert clinicians, and they also

appear to be better able to identify sources of dataneeded for hypothesis testing.10 We believe many newtherapists, like many new physicians, often conduct aplethora of tests because: (1) they have been taughtmethods of patient management that require suspensionof hypothesis generation until all the data are collected,or (2) they do not have enough experience to generatea tentative idea (hypothesis) on which to base a focusedexamination strategy. We recognize that, for somepatients, therapists may be unable to generate examina-tion strategies, and the algorithm calls for consultationwhen this occurs and provides a mechanism for docu-menting and justifying the use of a consultant.

When using the HOAC II as a guide to documentation,therapists must describe their examination strategies,including how they arrived at these strategies (based onavailable data) and why they believe the chosen exami-nation techniques will lead to information that can beused to confirm or deny hypotheses. This may appear torequire a lot of information. Notes in the patient’smedical record, however, may be as simple as “thepatient’s inability to walk down stairs may be due tobalance problems. Testing of balance appears to be mostimportant, and tests of muscle force and range ofmotion will be conducted to rule out less likely causes ofthe functional limitation.” In this example, the balancetesting directly addresses the hypothesis, whereas muscleforce measurements and range-of-motion measurementscould lead to rejection of the hypothesis. The importantelement is that a link exists between the logic that guidesthe examination strategy, the information available, andthe therapists’ hypothesis. This does not require elabo-rate documentation on the part of the therapist.

Conduct the Examination and Analyze the DataExamination procedures for a given type of patient maybe governed by departmental policies, critical paths, or avariety of other influences. Ideally, approaches shouldbe data driven (evidence based) and based on researchsuggesting best methods of examination and data anal-ysis.11 The HOAC II does not specify how or what toexamine, but, for the process to be useful, the examina-tion must follow logically from the examination strategyand not include extraneous procedures if they are notpart of the examination strategy. That is, examinationprocedures should be related to the tentative hypothe-ses, either to confirm or to reject those hypotheses. Themeasurements obtained during this phase should be ofthe type and quality specified by the APTA’s Standards forTests and Measurements in Physical Therapy Practice.12

For documentation, all descriptions and analysis of thedata obtained during the examination should be clear.Reasons why hypotheses were supported or rejectedneed to be specified, and, when findings call for addi-


��

��

��

��

��



tional examination procedures, this should also bedescribed.

Add NPIPs to the Problem ListJust as existing and anticipated problems are on the PIPslist, existing and anticipated problems are on the NPIPslist. The anticipated problems require special consider-ation because they involve prevention, whereas the cur-rent problems are those, including functional limitationsand disabilities, that were not initially described by thepatient. NPIPS may be identified as early as the initialdata collection phase, but they do not formally appear inthe HOAC II until after the examination, when theNPIPs list is completed.

Sometimes, particularly with children or those withcommunication disorders, caregivers or family membersmay describe current problems. In this case, the prob-lems may be described in the initial data collectionphase. These problems are placed on the NPIPs list, but,in the context of the HOAC II, will be managed in asimilar way to the other existing problems on the PIPslist. The problems are not different in nature, but only inthe source of identification. The therapist, however, isresponsible for the management of the problems on theNPIPs list regardless of the source that identified theproblem.

Anticipated problems are different than existing prob-lems, and, in the HOAC II, management of anticipatedproblems is a central feature. Following a transtibialamputation, for example, a person is likely to develop aknee-flexion contracture.13 The therapist is likely toknow this, and the patient is not likely to know this. Thetherapist also will know that if a contracture develops,the patient may be unable to use a prosthesis and maylose function.

Identification of anticipated problems often requirestherapists to consider anticipated impairments to pre-vent functional limitations and disability, but anticipatedproblems may also be pathologies. A therapist, forexample, should be aware that returning a patient with acompromised cardiovascular system to full activity with-out the patient being able to monitor his or her own vitalsigns could cause a cerebrovascular accident (CVA) ormyocardial infarction. Here the anticipated problemsare pathologies that could be prevented by teaching thepatient how to monitor his or her cardiovascular status.The patient also may be the source for anticipatedproblems, and, although these are in the PIPs list, theyare managed in a way that is similar, in the context of theHOAC II, to the way all other anticipated problems aremanaged.

Anticipated problems are usually risk factors, for futurepathologies, impairments, functional limitations, anddisabilities. The problem is the risk factor, and theintervention will be aimed at eliminating the risk fac-tors. Sometimes an exacerbated risk factor may becontributing to functional limitation or disability. In aperson with low back pain, for example, inappropriatelifting techniques may be the reason for an existingproblem (ie, activities cause pain, which limits function),but continued use of poor techniques following thecurrent episode could lead to recurrence. Poor liftingtechniques may be a cause of an existing problem, andthis needs to be addressed when the therapist generateshypotheses regarding the causes of existing problems.The poor lifting techniques also could be the cause of ananticipated problem because they put the patient at riskfor future disability.

Justification for HypothesesThe therapist makes 2 types of justification based on thenature of the problem (existing or anticipated) andchooses one of 2 paths in the algorithm. Existing prob-lems require one type of argument, that is, hypothesesabout the diagnosis that detail what needs to be changedto eliminate existing problems. Anticipated problemsrequire a different kind of justification for the elimina-tion of risk factors and a case as to what may happenwithout intervention. Both types of justification shouldbe evidence based to the extent possible.

Generate a Hypothesis (or Hypotheses) as to Why theProblems ExistEach existing patient problem has an underlying causeor causes. In the HOAC II, the cause is usually due to animpairment that is present, but in some cases the causecould also relate to pathology, functional limitations,societal limitations, or disabilities. Interventions, webelieve, need to be focused on eliminating causes ofproblems. However, unless clinicians state, during clini-cal problem solving and documentation, why theybelieve problems exist, it is often difficult to justifyinterventions or to see how they relate to problems.Students, for example, often find it difficult to see howtheir clinical instructors determined what interventionto use. Similarly, payers may not be able to discern whya therapist focuses on an isolated motor skill instead of afunctional task during intervention unless the therapisthypothesizes that a relationship exists between the iso-lated skill and functional activities. The hypotheses gen-erated during this step provide the link between thetherapist’s diagnosis and the intervention. No interven-tion for an existing problem should be conducted unlessit relates to the hypothesized cause of a problem.

Often the causes of disabilities will be the presence ofpathologies, impairments, and functional limitations.



Many physical therapy interventions focus on impair-ments and functional limitations, and therefore mostdiagnostic hypotheses will be directed at the impairmentand functional limitation dimensions. Sometimes, how-ever, therapists will attempt to eliminate a pathology.When this occurs, the pathology is the hypothesizedcause. When a therapist believes that a wound fails toclose because of infection, for example, the hypothesiscould be at the level of a pathology; that is, unless thesepsis is eliminated, the wound will not close. This wouldbe a testable hypothesis because wound cultures couldbe requested. Hypotheses that identify suspected pathol-ogies often cannot be tested by physical therapistsbecause most therapists are unable to request invasivetests or radiological diagnostic tests. Therapists usuallyneed to consult with and possibly refer patients to aphysician to determine when a pathology is identified asthe diagnosis in a hypothesis.10

The HOAC II, like the original algorithm, places anemphasis on hypothesis generation and requires thetherapist not only to determine what may be causing theproblem (eg, loss of muscle force, loss of motion), but toalso postulate as to the magnitude of the deficits (eg, howmuch weakness a patient has and how much force wouldbe needed for the problem to be eliminated). Theamount of force needed will serve as the testing criteriafor the hypothesis. Therefore, when generating hypoth-eses, therapists must understand that in a subsequentstep they must quantify what must be achieved to elimi-nate the problem. One way of determining whether ahypothesis is appropriate is to consider whether suchtesting criteria could be generated. In the wound exam-ple, the criteria would be a report of a negative culture.This example demonstrates that even when the hypoth-esis is at the level of pathology, generation of testingcriteria must be possible.

Hypotheses that identify impairments as the cause ofdisabilities and functional losses are even easier togenerate. If a person cannot walk following a CVA, forexample, it would be incorrect in the HOAC II tohypothesize that the cause is damage to the motorcortex. Although this may be true, the quantification ofthe type and extent of pathology is not observable andmeasurable by physical therapists. The diagnostichypothesis may be that the person cannot walk becausehe or she lacks the ability to generate sufficient quadri-ceps femoris muscle force during stance. In this exam-ple, the problem is a functional deficit, and the hypoth-esis relates the functional deficit to an impairment. Thetesting criteria will be the amount of force the therapistbelieves the patient needs to be able to generate toeliminate the problem (ie, to walk). Had the hypothesisidentified a pathology (damage to the motor cortex),the pathology could not be measured by physical thera-

pists, and, more importantly, the intervention is notdesigned to change the pathology, but rather the impair-ment and disability that the pathology caused. In addi-tion, the pathology (as measured with magnetic reso-nance imaging, for example) would likely beunchanged, even though the intervention successfullydealt with the impairment or functional limitation.

The critical elements of hypotheses are that they dealwith elements that would be affected by the interventionand that they must be sufficiently clear to allow for thegeneration of testing criteria. The testing criteria thattherapists generate must represent pathology, impair-ments, or functional loss that can be measured in clinicalpractice. As discussed earlier, when a previously undiag-nosed pathology is hypothesized to be present, consul-tation with or referral to a physician may be required toconfirm the hypothesis. A problem may have more thanone underlying cause, and, in these cases, the therapistmay generate multiple hypotheses. The therapist alsowould generate testing criteria for each hypothesis. Thismight occur, for example, when weakness and a lack ofcoordination are hypothesized to be the reasons why aperson can no longer ambulate independently.

For Each Anticipated Problem, Identify the Rationale forBelieving Anticipated Problems Are Likely to OccurUnless Intervention Is ProvidedPhysical therapists, like many other health care profes-sionals, share beliefs about what is happening and whatmay happen to their patients. Some of these beliefs arebased on data that identify risk factors, factors that onceeliminated should reduce the possibility of future nega-tive health outcomes. The Framingham study, for exam-ple, identified many risk factors for cardiovascular dis-ease.14 Epidemiological studies of this type are usuallythe means for justifying interventions designed to elim-inate risk factors. Unfortunately, data often are lackingfor beliefs that health care professionals have about riskfactors.

On what data do physical therapists act? The question isa legitimate patient management and resource alloca-tion query. Without evidence to support the value ofelimination of risk factors, the possibility of excessiveintervention exists. Too little intervention for risk factorsalso is a possibility. The HOAC II provides a mechanismfor therapists to use either epidemiological data ortheoretical constructs to justify interventions aimed atreducing risk factors. The former is data based orevidence based, whereas the latter uses argumentationand logic that should have some scientific basis.Evidence-based arguments are preferred.15

By using the algorithm, justification is explicit ratherthan implicit and can be discussed by all relevant parties.


��

��

��

��

��



We contend that unless physical therapists can provideeither good presumptive arguments or data to supportinterventions aimed at reducing or eliminating riskfactors, the role of therapists in prevention will beincreasingly challenged and possibly eliminated. Whentherapists provide evidence to support their decisions,however, little reason exists to deny interventions if therisk-benefit ratio is reasonable. When therapists can onlyprovide arguments, the case is less clear.

When using the HOAC II, we believe therapists mustdiscuss all anticipated problems in the documentationand provide arguments and evidence as to why theybelieve that a problem would occur without interven-tion. This applies to justification for all interventionsrelated to anticipated problems and diminishes thelikelihood of unnecessary interventions or of interven-tions continuing after they are no longer necessary. Webelieve this documentation will not only enhance patientcare but also will make our interventions more credible,particularly those aimed at prevention.

Refine Problem ListThe problem list at this point in the algorithm contains2 types of problems (existing and anticipated) derivedfrom 2 sources (the patient and all other sources). Thetherapist needs to determine whether the problems canbe addressed by physical therapy interventions. If thepatient needs the intervention of another health carepractitioner, the therapist needs to make a referral anddocument why the referral is necessary. If the therapistbelieves that the problem cannot be addressed, such aswhen no intervention would help, the therapist needs todiscuss this with the patient and: (1) remove the prob-lem from the list of problems to be addressed by physicaltherapy, (2) document why the problem could not beeliminated, and (3) document the discussion that tookplace and describe what was agreed on with the patient.The therapist may believe that some problems can onlybe modified and not be fully eliminated. Again, thetherapist should make this modification in the problemlist, discuss it with the patient, and document the natureof the discussion.

For Each Problem, Establish One or More Goals

Existing problems. In the HOAC II, like the originalalgorithm, there is one type of goal—something that thepatient needs to achieve. Goals are almost exclusivelyexpressed in terms of functional activities that thepatient wants or needs to perform. Often therapists andothers have used the term “short-term goal” not only toindicate something that can be achieved in less timethan long-term goals, but also to indicate changes inlevels of impairments they believe are related to long-term goals. A therapist might say, for example, that a

short-term goal is teaching the patient an exercise tostrengthen a paretic limb. Strengthening would relate toa long-term goal in which that limb might be used forambulation. We believe this approach is confusing.Changes in the force-generating capacities of musclesmay indeed help some patients to achieve functionalactivities, but the goal is the function—strengtheningmay or may not be a means to that end. We contend thatif all a therapist achieves is increased force capacity, thepatient has gained little or nothing from therapy. Toconsider a change solely in an impairment as meeting agoal, in our opinion, is almost always inappropriate.

In the HOAC II, impairment changes are monitoredthrough the testing criteria and usually are not goals. Allof the goals used in the HOAC II must representmeaningful accomplishments.16 That is, meeting a goalas written in the algorithm means the patient’s functionhas changed meaningfully. Some functions may berecovered sooner than others, and these can be identi-fied as short-term goals. The overriding issue is that long-and short-term goals represent the same kind of phe-nomenon (meaningful change for the patient) and theonly difference is the time needed to achieve them. Thesimplest way of checking whether a goal is reallymeaningful in the HOAC II context is to consider:(1) whether anyone would feel therapy was worthwhile ifthis is all that is achieved and (2) whether the payerwould find therapy to be worthwhile if this is all that isachieved.

Many patients, such as people with CVAs, may, in theory,have many problems, and they might have a rather longlist of goals they want to achieve to perform activities ofdaily living (ADL), instrumental activities of daily living(IADL), and other activities. Goal lists for such patientsmight seem almost infinite in scope and impractical inlength. For patients such as these, the therapist needs towork with the patient to identify those goals that aremost important and those that are indicative of variouslevels of difficulty. A therapist may list as a goal “inde-pendence in brushing teeth,” for example, and use thisto represent a variety of similar tasks requiring eye-handcoordination, such as using utensils for eating. In thisway, not all goals have to be listed, but rather thereshould be those that are especially important to thepatient and those that represent a hierarchy and diver-sity of motor skills that could serve as goals.

Anticipated problems. Therapists and patients need towork together to eliminate existing problems to achievegoals that they have delineated together. The goal for ananticipated problem is to prevent the problem fromoccurring.



For Each Existing Problem, Establish Testing CriteriaIn the HOAC, the word “hypothesis” is used because ithas a mechanism for therapists to test whether theirideas about causes of problems (ie, their diagnoses) maybe correct. Only controlled studies can provide data as towhether interventions lead to desired effects. In clinicalpractice, however, the issue is whether we can provideinterventions that we believe are effective. We believeone mechanism by which that can be done is the use ofa systematic approach to patient management. TheHOAC II, we believe, allows such an approach for theintegration and use of the best evidence available. TheHOAC II requires hypothesis testing in clinical practice.In the context of the HOAC II, the therapist has ahypothesis as to what is causing a problem, and usuallythat is an impairment leading to diminished function.An impairment is a loss of function in an organ orsystem, such as a loss of motion, strength, or coordina-tion. These losses are all measurable. Therefore, if theintervention is focusing on the cause of the problem, asthe impairments lessen, function should improve. Theproblems should be diminishing, and goals should becloser to attainment. At times, a problem may be hypoth-esized to be caused by multiple impairments. But how dowe know whether we have identified the correct diagnos-tic hypothesis?

In the HOAC II, changes in the impairment measure arealmost always monitored. The level of improvement inimpairment that the patient needs to achieve to elimi-nate the problem is called the “testing criteria.” Whenmultiple impairments occur, each will have to be mea-sured, with testing criteria established for each. Whentesting criteria are met, the problem should have beeneliminated and the related goals achieved. In this way,the therapist tests the original hypothesis for existingproblems.

For Each Anticipated Problem, Establish PredictiveCriteriaThe conceptual basis for the testing criteria comes fromthe application of traditional scientific methods ofinquiry into clinical practice. Unfortunately, this cannoteasily be done for anticipated problems. In science,proving a negative is often seen as impossible becausehypotheses are not testable in the usual sense. If weintervene to prevent a contracture, for example, wecannot prove that we achieved anything. The failure of acontracture to develop may be due to an intervention orbecause a contracture would not have developed any-how. With an anticipated problem, however, we canargue that, based on what is known, something mighthave occurred had we not intervened. Therefore, themeans of justifying interventions focused on preventionis not in this part of the algorithm, but rather it isdescribed in the section where therapists supply the

rationale for each anticipated problem (see sectiontitled “For Each Anticipated Problem, Identify the Ratio-nale for Believing Anticipated Problems Are Likely toOccur Unless Intervention Is Provided”).

The testing criteria for existing problems are used toexamine the viability of the hypothesis. The predictivecriteria for the anticipated problems are different fromthe testing criteria. A goal for an existing problem can beachieved within a known time period. If we are trying tokeep something from happening, when do we declarewe have succeeded? In health care, often the best we cando is to eliminate risk factors; therefore, the predictivecriteria relate to risk factors. If risk factors can beeliminated during some finite time period, the predic-tive criteria would reflect this possibility.

For example, if a patient is seen as being at risk for thepostsurgical development of pneumonia (a pathology),pneumonia would be an anticipated problem. Physicaltherapy interventions may be gait training and breathingexercises. Both of these interventions are preventivebecause they relate to the potential reduction in risk ofpneumonia. The predictive criteria for ambulation maybe a certain distance walked per day, whereas thepredictive criteria for the breathing exercises may be aninspiratory level with an inspirometer and an observedlevel of competence in generating a productive cough.When these predictive criteria are achieved, the patientshould no longer need the preventive interventions.

This finite situation can be contrasted with people whohave permanent disabilities and chronic injuries whomay have to reduce risk factors for the rest of their lives.A patient with recurrent back pain, for example, may betaught prophylactic exercises, and the predictive criteriamay be a level of competence and degree of adherencein doing those exercises. When the desired level ofcompetence and adherence is achieved—that is, whenthe predictive criteria have been achieved—the patientwould no longer need ongoing physical therapy inter-vention. The assumption is that the patient would con-tinue to carry out the exercises as taught, or that thetherapist might need to see the patient periodically todetermine whether the predictive criteria are still beingmet (ie, the patient is still performing the exercises withthe appropriate frequency and in the proper manner).

The predictive criteria are used to determine how longinterventions designed for prevention should be carriedout. In this way, predictive criteria are somewhat similarto goals, but they exist only for anticipated problems.They are not goals because they are worth achieving onlyif sufficient evidence indicates that a problem mightoccur. The value of achieving the predictive criteria is


��

��

��

��

��



entirely dependent on the case made for anticipatingthat a problem might occur.

Establish a Plan to Reassess Testing andPredictive Criteria and Establish a Plan toAssess Problems and GoalsHypotheses often require multiple testing criteria, andchanges in the impairments measured for these criteriamay not all change at the same rate. Similarly, achieve-ment of various predictive criteria may not happen at thesame time. Measuring impairments and disabilities anddoing a re-evaluation at every session is time-consumingand impractical. Therapists should have reasonableexpectations as to when meaningful and therefore mea-surable changes will occur and should plan are-evaluation schedule accordingly. Similarly, not allgoals can be achieved at the same time, and thereforethey should be checked based on a logical plan (ie,short-term goals should be checked sooner than-longterm goals). By committing to an evaluation schedule, atherapist using the HOAC II has identifiable points intime when the patient’s status will be reconsidered.Without such a plan, re-evaluation is often chaotic, andmeasurements may be obtained at intervals that maymake interpretation of data difficult.

Plan Intervention Strategy and TacticsIf the therapist thinks muscle weakness is the impair-ment contributing to a disability, the most obviousapproach would be to use exercise to increase theforce-generating capacity of the involved muscles. Thestrategy would be the use of exercise. Describing thestrategy alone is insufficient, because many types ofexercises exist. The HOAC II asks therapists to describethe tactics (specific exercises and frequency) they woulduse. If we were dealing with an anticipated problem(such as the development of postoperative pneumonia),there might be 2 strategies: (1) teach the patient how toclear his or her airway and (2) teach the patient preven-tive measures such as frequent ambulation and use of aninspirometer. The tactic for the first strategy (airwayclearance) may be to have the patient cough a specifiednumber of times per hour (and the patient could beshown how to determine if the cough is productive). Thetactic for generalized prevention might be correct use ofan inspirometer 5 times daily and ambulation 5 timesdaily. Strategies are broad statements of what types ofthings need to be done, whereas tactics are the elementsof the intervention. Tactics specify the frequency, dura-tion, and intensity of the interventions.

Implement TacticsOnce tactics have been identified, they need to beimplemented. Most often the therapist will be doing theimplementation. Sometimes, as when a person has ahome exercise program, the patient may be doing the

intervention. Family members, other health care person-nel (eg, physical therapist assistants), and other caregiv-ers all may have a role in implementing tactics. Thephysical therapist, however, should note who is imple-menting which tactics. We believe the therapist mustrecognize that, as long as these tactics are part of thephysical therapy plan of care, the therapist must assumeresponsibility for overseeing, evaluating, and determin-ing whether modifications should be made to tactics.

Part 2In Part 1 of the HOAC II, the therapist working with thepatient and others developed an intervention plan (aseries of strategies and tactics that is conceptually similarto the plan of care as defined in the Guide).6 Justifica-tion for the interventions was based on the therapist’sconcepts of what was causing problems. Therefore, bydefinition, much of what occurs in Part 1 arises fromconceptual models that can only be examined in thecontext of intervention (eg, did the intervention lead toa desired outcome?). Part 2 is far less conceptual innature and consists of questions that are designed toprovide insights into whether any aspect of patientmanagement is deficient, including whether the originalgoals were viable.

The steps in Part 2 can be used for documentation, orthey can be used to less formally guide decision making.The most important element, however, is that, by usingPart 2, the therapist must account for all changes ingoals, tactics, strategies, and hypotheses. In addition, thetherapist needs to document whether the criterion mea-sure chosen is still viable and whether it is still reasonableto expect to see the desired change in the criterionmeasure. Part 2 not only assists in the evaluation process,it provides the logical framework for examining theeffects of all interventions. Use of Part 2 requires thetherapist to document what happened to a patient, evenif the result is an acknowledgment that the result was lessthan was expected. Documentation may be particularlyuseful on occasions when factors outside of the thera-pist’s control led to a termination of the intervention.For example, by following the steps in Part 2, a therapistcan make an argument to a payer that goals were notachieved (even though progression was being made onthe criterion measure) because there was too little timeallowed for the intervention.

Part 2 consists of 2 flow diagrams. The first diagram(Fig. 3) leads the therapist through a series of questionsfor all existing problems (regardless of who generatedthem). The second diagram (Fig. 4) also consists of aseries of questions, but these questions relate to antici-pated problems (regardless of who generated the prob-lem list). The peculiar nature of prevention (ie, thera-pists may take credit for what does not occur by making



sure a risk factor is reduced or eliminated) leads tosomewhat different questions. The most notable differ-ence is that the first question when dealing with antici-pated problems is asking whether the problem hasoccurred. If it has, prevention did not work, and a newproblem needs to be added to the existing problem list.

Examining the Hypothesis for Existing ProblemsIf a patient’s goals are met (the problems are resolved),the question remains as to whether this occurredbecause of the intervention. Although causality cannotbe claimed in the absence of controlled studies, thealgorithm and use of the testing criteria allow therapiststo gain some insights as to whether their approachesseemed appropriate and their interventions beneficial andtherefore whether their hypotheses were appropriate.

When therapists set the testing criteria, they are statingthat a level of performance (usually of an impairmentmeasure) is needed for the goal to be achieved. If thegoal is achieved and the testing criteria are not met, thetherapist’s hypothesis is incorrect (or the criteria’s levelswere incorrect). If the testing criteria are met and thegoal is not achieved, the hypothesis is at best incomplete;that is, other causes may exist in addition to thoseidentified, or those identified are irrelevant. These areabsolute examples. What is less clear is what is happen-ing when there is movement toward meeting goals andwhen there is also an indication that the impairmentsmeasured for the testing criteria are also becoming lesspronounced. In these cases, no simple test of the viabilityof a hypothesis exists, so the therapist must extrapolateand consider the overall picture and determine whetherthe hypotheses and criteria should be maintained in thesame form.

When a therapist thinks a problem has multiple causesand generates multiple hypotheses, it is impossible to saywith certainty whether achieving appropriate levels of allthe testing criteria led to attainment of a goal. Thepossibility exists, for example, that if there were 3hypotheses, 2 of the hypotheses were correct and thethird hypothesis was either redundant or unnecessary.When all testing criteria are achieved, the therapist hasno way of knowing what would have happened with thispatient if only 2 hypotheses had been met.

Following a CVA, a patient might be incapable ofdressing. Among the many possible causes of this deficitcould be: (1) weakness, (2) lack of coordination, and (3)poor position sense. All 3 might be hypothesized ascauses of the problem. Testing criteria for weaknesscould be a force level obtainable on a hand dynamom-eter. For the lack of coordination, the testing criteriamight be a level of performance on a coordination test,and, for position sense, the testing criteria might be the

ability to place a limb on a target with less than aspecified number of errors. If all 3 criteria were met andthe patient achieved the goal of dressing himself orherself, the therapist could not be certain whether thisgoal still could have been obtained if only 2 of the 3testing criteria were met. The therapist, however, maydevelop an opinion based on the time course of events;that is, how did the attainment of the goal over timerelate to changes in the testing criteria? This caseillustrates how, even in the absence of being able todefinitively test hypotheses, therapists can better under-stand patient management by use of the algorithm. Inthis manner, the HOAC II serves as a means of ongoingfeedback for professional development, independent ofwhat occurs with each patient.

SummaryThe HOAC II was designed to facilitate the use ofscience and evidence in practice, and to do so in amanner that is not intrusive on clinical practice. Webelieve that much of what we ask clinicians to do in thealgorithm is already part of their practice but that itoccurs in a less defined manner and without a contextfor documentation and discussions among colleagues.Among the differences between this version and theoriginal HOAC are the mechanisms for justifying pre-vention and, more importantly, for developing measur-able outcomes related to prevention as well as definingthe time it will take to achieve reduction of risk factors.

References1 Rothstein JM, Echternach JL. Hypothesis-oriented algorithm forclinicians: a method for evaluation and treatment planning. Phys Ther.1986;66:1388–1394.

2 Delitto A, Snyder-Mackler L. The diagnostic process: examples inorthopedic physical therapy. Phys Ther. 1995;75:203–211.

3 Jette AM. Introduction: physical disability. Phys Ther. 1994;74:379.

4 Jette AM. Physical disablement concepts for physical therapyresearch and practice. Phys Ther. 1994;74:380–386.

5 Feder G, Eccles M, Grol R, et al. Clinical guidelines: using clinicalguidelines. BMJ. 1999;318:728–730.

6 Guide to Physical Therapist Practice. 2nd ed. Phys Ther. 2001;81:9–744.

7 Pope A, Tarlov A, eds. Disability in America: Toward a National Agendafor Prevention. Washington, DC: National Academy Press; 1991:84–89,223–241.

8 Elstein AS, Shulman LS, Sprafka SA. Medical Problem Solving: AnAnalysis of Clinical Reasoning. Cambridge, Mass: Harvard UniversityPress; 1978.

9 Payton OD. Clinical reasoning process in physical therapy. Phys Ther.1985;65:924–928.

10 Goodman CC, Snyder TEK. Differential Diagnosis in Physical Therapy.3rd ed. Philadelphia, Pa: WB Saunders Co; 2000.

11 Sackett DL, Haynes RB, Guyatt GH, Tugwell P. Clinical Epidemiology:A Basic Science for Clinical Medicine. 2nd ed. Boston, Mass: Little, Brownand Co Inc; 1991.


��

��

��

��

��



12 Task Force on Standards for Measurement in Physical Therapy.Standards for tests and measurements in physical therapy practice. PhysTher. 1991;71:589–622.

13 May BJ. Assessment and treatment of individuals following lowerextremity amputation. In: O’Sullivan SB, Schmitz TJ, eds. PhysicalRehabilitation: Assessment and Treatment. 4th ed. Philadelphia, Pa: FADavis Co; 2000:632–633.

14 Dawber TR. The Framingham Study: The Epidemiology of AtheroscleroticDisease. Cambridge, Mass: Harvard University Press; 1980.

15 Straus SE, Sackett DL. Getting research findings into practice: usingresearch findings in clinical practice. BMJ. 1998;317:339–342.

16 Randall KE, McEwen IR. Writing patient-centered functional goals.Phys Ther. 2000;80:1197–1203.

Appendix.Terms Used in the Hypothesis-Oriented Algorithm for Clinicians II (HOAC II)

Anticipated Problems:

These can be identified by the patient, the physical therapist, or anyother person and are statements that describe deficits that the therapistbelieves will occur if an intervention is not used for prevention.

Examination Strategy:This is the plan for examination that a physical therapist uses based onthe therapist’s experience, available data relating to the patient, andinformation on similar patients. Because not all possible tests andmeasures are used, the choice is considered a hypothesis-driven strat-egy in the HOAC II.

Existing Problems:These can be identified by the patient, the physical therapist, or anyother person and are statements that describe deficits in a person’sfunction (disability).

Goals:Functional deficits are problems, whereas goals are descriptions offunction that will be recovered as a result of one or more interventions.

Hypothesis:The reason that a patient’s problems (which are usually at the disabilitylevel) exist is not necessarily known, but in order for a physical therapistto carry out an intervention, the therapist must have an idea as to theunderlying causes. In the HOAC II, the therapist’s conjecture as to thecause is a hypothesis. Often there will be more than one hypothesis, andusually the hypothesis will involve one or more impairments causing adeficit in function (ie, a disability).

Intervention Strategy:These are the overall types of interventions that the physical therapistbelieves are needed to alleviate problems (eg, exercises designed toincrease range of motion are a strategy, whereas the specific exercisesare tactics).

Non–Patient Identified Problems (NPIPs):These are problems identified (at least initially) by people other than thepatient but that are added to the patient’s problem list after consultationwith the patient (these can be existing or anticipated problems).

Patient-Identified Problems (PIPs):These are problems identified by the patient (these can be existing oranticipated problems), and because they are generated by the patient,they cannot be removed from the problem list without the patient’sconsent.

Predictive Criteria:These are critical values (thresholds) for measurements, which, if met,would indicate that one or more problems will most likely be avoidedbecause risk factors were reduced or eliminated. Sometimes the mea-surement may be how often someone does a task or whether a patientdemonstrates competency in a prevention program (eg, does stretchingor prophylactic back exercises).

Tactics:These are the elements of an intervention. For instance, the exercises ortechniques used to treat the patient or client are the specific elements ofthe intervention, whereas the overall purpose of the interventions is thestrategy.

Testing Criteria:These represent critical values (thresholds) for measurements, which, ifachieved, would suggest the hypothesis (or hypotheses) is correct if theassociated problem(s) is resolved (these are most often measurements ofimpairments).



2003; 83:455-470.PHYS THER. RiddleJules M Rothstein, John L Echternach and Daniel L(HOAC II): A Guide for Patient ManagementThe Hypothesis-Oriented Algorithm for Clinicians II

References

http://ptjournal.apta.org/content/83/5/455#BIBLfree at: This article cites 9 articles, 8 of which you can access for

Cited by

http://ptjournal.apta.org/content/83/5/455#otherarticles

This article has been cited by 7 HighWire-hosted articles:

Information Subscription http://ptjournal.apta.org/subscriptions/

Permissions and Reprints http://ptjournal.apta.org/site/misc/terms.xhtml

Information for Authors http://ptjournal.apta.org/site/misc/ifora.xhtml


http://ptjournal.apta.org/content/83/5/455#BIBL

http://ptjournal.apta.org/content/83/5/455#otherarticles


Documents

The Hypothesis Oriented Algorithm II