Originally published online July 21, 2011 Collections e ... · Originally published online July 21, 2011 PHYS THER.€2011; 91:1339-1354. and Robert Wagenaar Anna E. Barón, Linda

doi: 10.2522/ptj.20100236Originally published online July 21, 2011

2011; 91:1339-1354.PHYS THER. and Robert WagenaarAnna E. Barón, Linda Tickle-Degnen, Deborah A. Hall Margaret Schenkman, Terry Ellis, Cory Christiansen,Middle-Stage Parkinson DiseasePerformance Among People With Early- and Profile of Functional Limitations and Task

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Profile of Functional Limitations andTask Performance Among PeopleWith Early- and Middle-StageParkinson DiseaseMargaret Schenkman, Terry Ellis, Cory Christiansen, Anna E. Baron,Linda Tickle-Degnen, Deborah A. Hall, Robert Wagenaar

Background. Overall functional ability declines over time in people with Parkin-son disease (PD). Established benchmarks are needed to allow clinicians andresearchers to facilitate meaningful interpretation of data.

Objective. The purposes of this study were: (1) to report typical values forstandard measures of functional ability commonly used in intervention studies andclinical practice with individuals in the early and middle stages of PD and (2) todescribe the profile of functional limitations using the Hoehn and Yahr (H&Y) stagesof disease and Unified Parkinson’s Disease Rating Scale (UPDRS) motor scores.

Design. Cross-sectional data were obtained from 5 different studies.

Methods. Three hundred thirty-nine patients were evaluated for disease severity(UPDRS motor score); functional capacity (Continuous Scale Physical FunctionalPerformance Test [CS-PFP]); balance and gait (Functional Reach Test [FRT], Timed“Up & Go” Test [TUG], 360-degree turn, Six-Minute Walk Test [6MWT], and Two-Minute Walk Test); and basic functional activities (supine-to-stand task, stand-to-supine task, and functional axial rotation [FAR]).

Results. The mean UPDRS motor score for the sample was 39.2 (SD�12.93). Ateach stage of PD (from least to most involved), scores on functional measuresindicated a significant and progressively reduced functional status. Limitations beganearly in the disease for the CS-PFP and FAR. Losses in performance were consistentacross all stages of disease for the CS-PFP, FRT, 6MWT, and FAR. Several measuresdemonstrated meaningful losses of function only in later stages of disease. Findingsextend current appreciation of functional limitations that begin early in PD and canguide the choice of functional outcome measures at different stages of diseaseseverity.

Limitations. Data were obtained only from participants in H&Y stages 1 through3 and only for some of the performance measures typically used.

Conclusions. The findings demonstrate that functional loss occurs at differentpoints in the disease process, depending on the task under consideration. Theresulting profile of functional limitations provides benchmarks that clinicians andresearchers can use to interpret and monitor status of patients.

M. Schenkman, PT, PhD, FAPTA,Physical Therapy Program, De-partment of Physical Medicineand Rehabilitation, School ofMedicine, University of Colorado,Mailstop C-244, 13121 E 17thAve, ED II South, Room L28–3106, Aurora, CO 80045 (USA).Address all correspondence toDr Schenkman at: [email protected].

T. Ellis, PT, PhD, NCS, Departmentof Physical Therapy and AthleticTraining, Sargent College ofHealth and Rehabilitation Sci-ences, Boston University, Boston,Massachusetts.

C. Christiansen, PT, PhD, Depart-ment of Physical Medicine andRehabilitation, School of Medi-cine, University of Colorado,Aurora, Colorado.

A.E. Baron, PhD, School of PublicHealth, University of Colorado,Aurora, Colorado.

L. Tickle-Degnen, OTR, PhD,FAOTA, Department of Occupa-tional Therapy, Tufts University,Medford, Massachusetts.

D.A. Hall, MD, PhD, Departmentof Neurology, Rush Medical Cen-ter, Chicago, Illinois.

R. Wagenaar, PhD, Departmentof Physical Therapy and AthleticTraining, Sargent College ofHealth and Rehabilitation Sci-ences, Boston University.

[Schenkman M, Ellis T, Christian-sen C, et al. Profile of functionallimitations and task performanceamong people with early- andmiddle-stage Parkinson disease.Phys Ther. 2011;91:1339–1354.]

© 2011 American Physical TherapyAssociation

Published Ahead of Print: July 21,2011

Accepted: May 14, 2011Submitted: July 19, 2010

Research Report

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Overall ability to functiondeclines over time in peoplewith Parkinson disease (PD).

Shulman and colleagues,1 using theUnified Parkinson’s Disease RatingScale (UPDRS), were the first toexamine functional differences bystage of PD. Because performance ofbasic functional activities is criticalto maintaining independence andstaving off disability, considerableeffort has been directed towardinvestigating the effectiveness ofphysical intervention strategies formaintaining functional ability, despitethe progressive nature of the disease.Based on the accumulated evidence,it is clear that early physical inter-vention can have positive benefitsfor these individuals.2–5 Althoughthe UPDRS is the gold standard forquantifying response to interven-tions,6,7 this scale does not ade-quately describe the patient’s diffi-culties with physical function andparticipation and may be less respon-sive to rehabilitation interventionsthan to more specific measures offunction. For this reason, a variety ofperformance measures have beenused with people who have PD toexamine response to exercise. Often

included are measures of gross phys-ical mobility8 (eg, supine-to-standmaneuver), balance9 (eg, FunctionalReach Test [FRT],10 Timed “Up &Go” Test [TUG]11), and walking12

(eg, Six-Minute Walk Test [6MWT]13).However, ranges of typical values forthese measures in patients with PDare lacking in the literature. There isa need for established benchmarksto allow clinicians and researchersto compare their data with pointsof reference, thus facilitating moremeaningful interpretation.

This article reports typical values, bydisease severity, for a variety of stan-dard measures of function com-monly used in exercise interventionstudies and clinical practice. Theprofile of functional limitations atparticular stages of disease severity isdescribed based on both Hoehn andYahr (H&Y) stages of disease, whichis particularly useful for physical

therapist clinicians, and UPDRSscores, the gold standard forresearchers and neurologists. Agreater appreciation of functionallimitations associated with differentstages of disease progression mayguide timely initiation of rehabilita-tion interventions, with the goal ofdelaying functional decline. Estab-lished benchmarks can inform selec-tion of measures for longitudinaltracking of function for peoplewith PD.

MethodSamplesThe data in this report are from 3studies conducted by Schenkmanand colleagues at Duke University8,14

and the University of Colorado(unpublished) and from 2 studiesconducted at Boston University byEllis and colleagues15 and Tickle-Degnen and colleagues.16 Many ofthe measurements obtained in the 5

Available WithThis Article atptjournal.apta.org

• eFigure 1: Continuous ScalePhysical Function PerformanceTest (CS-PFP) score distributionby Hoehn and Yahr stage

• eFigure 2: Balance and gaitmeasure score distributions byHoehn and Yahr stage

• eFigure 3: Supine-to-stand testand functional axial rotation(FAR) (worse side only) scoredistribution to Hoehn and Yahrstage

• Discussion Podcast with authorMargaret Schenkman andKathleen Gill-Body, moderated byRebecca Craik.

The Bottom Line

What do we already know about this topic?

Several measures of physical function are available to clinicians andresearchers to assess walking, balance, and general mobility in peoplewith Parkinson disease. Despite the wide use of these measures, there islittle information to guide the interpretation of the findings.

What new information does this study offer?

This study provides typical values for standard measures of walking,balance, and general mobility in people with Parkinson disease anddescribes the profile of functional limitations in relation to diseaseseverity. This information provides established benchmarks to help clini-cians and researchers interpret their findings when administering thesemeasures.

If you’re a patient, what might these findings meanfor you?

Your physical therapist may administer physical performance tests tomeasure your walking ability, balance, and general mobility. The infor-mation presented in this article will help your physical therapist chooseappropriate measures and compare your performance to the performanceof other people with Parkinson disease.

Functional Limitations and Task Performance in Early- and Middle-Stage Parkinson Disease

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Table 1.Characteristics of the Sample and Comparison Across Sitesa

Variable Total SampleEllis et al15 and

Tickle-Degnen et al16

Schenkman andColleagues8,14,unpublished data P

Sample size, n 339 183 (54.0%) 156 (46.0%)

Age (y)

Mean (SD) 66.1 (9.34) 65.3 (8.91) 67.0 (9.77) .102

Range 37–92 37–83 46–92

Sex (male), n (%) 238 (70.2%) 131 (71.6%) 107 (68.6%) .609

Education (highest degree), n (%)

�.001

� High school 5 (2.0%) 0 (0.0%) 5 (3.6%)

High school 53 (20.7%) 24 (20.7%) 29 (20.7%)

Professional certificate 11 (4.3%) 5 (4.3%) 6 (4.3%)

Associate’s degree 20 (7.8%) 2 (1.7%) 18 (12.9%)

Bachelor’s degree 71 (27.7%) 22 (19.0%) 49 (35.0%)

Graduate degree 96 (37.5%) 63 (54.3%) 33 (23.6%)

Race, n (%)

1.000Asian or Pacific Islander 4 (1.6%) 2 (1.7%) 2 (1.4%)

Black (not of Hispanic origin) 4 (1.6%) 2 (1.7%) 2 (1.4%)

White (not of Hispanic origin) 248 (96.8%) 112 (96.6%) 136 (97.2%)

UPDRS total

Mean (SD) 39.2 (12.93) 40.9 (12.18) 36.2 (13.71) .006

Range 6.0–86.5 6.0–74.0 8.5–86.5

UPDRS motor

Mean (SD) 25.2 (9.56) 25.3 (9.28) 25.0 (10.08) .804

Range 2.0–59.5 2.0–50.0 5.5–59.5

UPDRS ADL

Mean (SD) 11.8 (5.23) 13.2 (4.88) 9.3 (4.88) �.001

Range 1.0–27.0 2.0–27.0 1.0–25.0

Hoehn and Yahr scale, n (%)

.558

Stages 1–1.5 10 (2.9%) 4 (2.2%) 6 (3.9%)

Stage 2 138 (41.2%) 80 (43.7%) 58 (38.2%)

Stage 2.5 104 (31.1%) 53 (29.0%) 51 (33.6%)

Stage 3 83 (24.8%) 46 (25.1%) 37 (24.3%)

Time since diagnosis (y)

Mean (SD) 6.0 (5.12) 7.1 (5.67) 4.7 (3.99) �.001

Range 0–32 0–32 0–23

MMSE

Mean (SD) 29.1 (1.03) 29.3 (0.96) 29.0 (1.09) .069

Range 25–30 27–30 25–30

PDQ-39

Mean (SD) 27.2 (12.71) 31.5 (11.07) 21.0 (12.46) �.001

Range 1.0–61.4 4.8–61.4 1.0–55.6

SF-36 physical function

Mean (SD) 68.9 (22.4) N/A 68.9 (22.4) N/A

Range 5–100 N/A 5–100

a UPDRS�Unified Parkinson’s Disease Rating Scale, MMSE�Mini-Mental State Examination, PDQ-39�39-item Parkinson’s Disease Questionnaire,SF-36�36-Item Short-Form Health Survey questionnaire, N/A�not applicable.




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studies overlapped; however, not allmeasurements were collected in allstudies, and thus the sample size foreach variable differs. The order andlength of testing varied among stud-ies; however, sessions typically werebetween 2 and 2.5 hours long, andall measures were administered onthe same day. Specific details are pro-vided in the primary articles.8,14–16

All data were collected in the medi-cation “on” state, which wasdefined as the time when the patientreported optimal effect of his or herPD medications (typically within anhour of medication intake). Forthose patients who participated inrandomized, controlled exerciseintervention studies,8,15,16 only base-line data were used.

Participants were in H&Y stages 1through 3,17 lived in the community,and ambulated independently, repre-senting a relatively wide range ofindividuals in the early and middlestages of PD. Participants wereexcluded if they had musculoskele-tal, neuromuscular (other than PD),or cardiovascular disorders thatwould interfere with ability to exer-cise. Participants also were excludedif they had a Mini-Mental StateExamination score of less than 24.Characteristics of the sample areshown in Table 1. The study cohortsof Schenkman et al8 were similarwith respect to age, race, and sexdistributions to those of Ellis et al,15

except that the latter sampleincluded a significantly higher pro-portion of patients with a graduate-level education. Clinically, thecohorts were similar with regard toH&Y stage and UPDRS motor scores.The study by Ellis et al,15 however,included patients with significantlylonger disease duration and higherUPDRS total, UPDRS ADL, and39-item Parkinson’s Disease Ques-tionnaire (PDQ-39) scores.18 Quality-of-life scores, characterized with the36-Item Short-Form Health Surveyquestionnaire (SF-36)19 and PDQ-39,

were consistent with mild to moder-ate disease severity.

Functional MeasuresMeasures of function were groupedinto 3 categories: (1) overall func-tional capacity, (2) balance and gait,and (3) basic functional activities.Table 2 summarizes informationrelated to administration and inter-pretation of these functional tests.Where available, data are providedfrom older adults who were healthyfor comparison.

Overall functional capacity was mea-sured using the Continuous ScalePhysical Functional PerformanceTest (CS-PFP).20–22 This standardizedtest of physical function was devel-oped and validated on a large sampleof older adults ranging from thoseliving in assisted living environmentsto elite athletes.20 Fifteen tasks areperformed serially, providing a morerealistic measure of overall capacityto carry out functional activities inthe home setting than typically usedsingle-task measures (eg, balance andgait measures). Performance wouldbe expected to be better if a task ismeasured in isolation than if the taskis measured in combination with 14other tasks because of the physiolog-ical demands of continuous func-tion. A higher score indicates greaterfunctional capacity. On completionof the test, participants rated theirperceived exertion23 for the entiretest.

Balance was measured using a vari-ety of tests with established validityand reliability. For the FRT,10,24 par-ticipants performed 2 practice trialsfollowed by 3 test trials, which wereaveraged. For the TUG,11,25–27 partic-ipants completed 1 practice trial fol-lowed by 2 test trials, which wereaveraged.28 For the 360-degree turnin standing, participants performedone practice trial followed by 2 testtrials, which were averaged.8,29

Gait function was assessed by meansof the Two-Minute Walk Test(2MWT) and the 6MWT. The 2MWTrequired 2 practice walks due toan initial training effect.30 Data fromthe third trial were analyzed. The6MWT, originally developed as ameasure of cardiovascular endur-ance,31 has been applied to adultswho were healthy and individualswith a variety of disorders, includingPD.31–34 Data were obtained from asingle trial.

Basic functional activities includedmeasures of supine-to-stand time,stand-to-supine time, and functionalaxial rotation (FAR). Time requiredto lie supine on a bed from a stand-ing position and to return to standingfrom the supine position wasrecorded following a single test.8 Forthe FAR measure,35 data were aver-aged from 2 trials to each side (leftand right). No significant differencewas detected between FAR to theright and the left (P�.49); only datafor FAR to the more limited side(worse measure) are reported.

PD Symptoms and SeverityParkinson disease was diagnosed ineach patient by a neurologist withfellowship training in movement dis-orders, with the exception of thesmall sample from Duke University,in which a general neurologist madethe diagnosis. Severity of PD wasmeasured using the UPDRS motorand total scores and the modifiedH&Y scale.6 The on-state UPDRS andmodified H&Y scores (scores whenmedications were most effective)were determined by a movement dis-order specialist or by another profes-sional trained by the study’s move-ment disorder specialist. The UPDRSmotor score provides a measure ofseverity of signs and symptoms (eg,bradykinesia, rigidity, tremor) of PD.The modified H&Y scale describesdisease severity more broadly, withstages 1 to 2 indicating mild disease,stages 2.5 to 3 indicating moderate




disease, and stages 4 to 5 indicatingsevere disease.36

Data AnalysisMeans, quartiles, standard devia-tions, and ranges of physical func-tion and quality-of-life measureswere calculated. Demographic anddisease stage data were tabulatedusing 2-way contingency tables withcounts and relative frequencies.Comparisons among groups (ie,H&Y stage or UPDRS scores) weremade using Wilcoxon rank sum testsfor quantitative measures and chi-square and Fisher exact tests forcount data. Data then were displayedgraphically, categorized in 2 ways.Modified H&Y stage of disease wasgrouped into stages 1 to 1.5, 2, 2.5,and 3. The UPDRS motor scoreswere grouped as follows: 1 to 15,15.5 to 30, 30.5 to 45, and 45.5 to 60.Linear trends in performance mea-sures were evaluated using linearregression. In order to test for a lin-ear trend, new variables were cre-ated that were equal to the numeri-cal categories of either UPDRS motoror H&Y scores (eg, 1, 2, 3, 4). Thesevariables were included in theregression models, and the coeffi-cients were interpreted as continu-ous covariates would be interpreted(eg, as a change in the outcome for aone-unit change in the category ofUPDRS). The Cohen f statistic wasused to report effect sizes of the esti-mated linear trends. An effect sizeof 0.15 is generally considered small,0.4 medium, and 0.6 large.37 All dataanalyses was performed using SAS/BASE and SAS/STAT software, ver-sion 9.2 of the SAS System forWindows.*

ResultsCharacteristics of the SampleThe full database comprised 339 par-ticipants (Tab. 1). Of these, 156 werefrom the studies by Schenkman and

colleagues8,14,unpublished data and 183were from studies by Ellis et al15 andTickle-Degnen et al.16 Age was nor-mally distributed (mean�66.1 years,SD�9.3, range�37–92). The samplewas 70.6% male and 96.9% white,98.0% had graduated from highschool, and 73.0% had earned ahigher degree. Mean years sincediagnosis of PD was 6.0 (SD�5.12),with 78.5% of the participants diag-nosed within the previous 10 years; afew of the participants (2.9%) hadthe disease for more than 20 years.

Using the modified H&Y scale, halfof the sample (56%) had moderatedisease (H&Y stages 2.5 or 3)(Tab. 1). The mean UPDRS totalscore was 39.2 (SD�12.93, range�6–86.5). The mean UPDRS motorscore was 25.2 (SD�9.56, range�2–59.5). In contrast to the H&Yscores, UPDRS motor scores werenearly normally distributed.

Physical Functional AbilityOverall functional capacity. Weexamined overall functional capac-ity, as measured by the CS-PFP, inrelation to both UPDRS motor scoreand H&Y stage (Tab. 3; Fig. 1; eFig.1, available at ptjournal.apta.org).The mean scores dropped byapproximately 10 points betweencategories of UPDRS motor score,with the exception of the last stage,in which they dropped by 20 points.A similar pattern was seen for theH&Y stages. Despite the consistentlylower CS-PFP scores, the RPEremained relatively constant(between 11 and 12) until a UPDRSmotor score of 45 had been reached,after which it rose sharply to amedian of 14 for participants withUPDRS motor scores of 45.5 to 60.

Balance and gait. For the FRT(Tab. 3; Fig. 2; eFig. 2, available atptjournal.apta.org), whether exam-ining the mean or median score,

there was an approximately 6-in†

drop in reach across levels of diseaseseverity. For the TUG, whetherexamining the mean or medianscore, values at all stages of severity(H&Y or UPDRS motor) were greaterthan 8 seconds. The TUG times(mean and median) were at least 2.5seconds longer at the highest level ofdisease severity (H&Y stage 3, UPSRSmotor score�45.5–60) comparedwith the lowest levels of diseaseseverity (H&Y stage 1–1.5, UPDRSmotor score�0–15).

For the 360-degree turn (Fig. 2, eFig.2), whether using the median ormean time, participants who weremost involved (H&Y stage 3) tookapproximately twice as long to com-plete the task as those who wereleast involved (H&Y stages 1, 1.5,and 2), with mean time ranging from3.32 to 7.34 seconds. Only about 2seconds discriminated between par-ticipants who were least and mostinvolved when measured with theUPDRS motor scores. In terms ofnumber of steps, there was a differ-ence of approximately 4 stepsbetween participants who were leastand most involved using either theH&Y stages or UPDRS motor scores.

Data from the 6MWT and 2MWT areshown in Table 3, Figure 2, and eFig-ure 2. Examining changes in 6MWTscores by H&Y stages, the medianwalk distance was 562 m for par-ticipants who were least involvedand 389 m for those who were mostinvolved, a difference of 173 m. Themajority of this difference occurredbetween H&Y stages 2 and 2.5, witha difference of 100 m observedbetween median values. Mean scoresshowed a similar pattern. Examining6MWT distance by UPDRS motorscores, the median score wasapproximately 200 m less for partic-ipants who were most involved com-pared with those who were least

* SAS Institute Inc, 100 SAS Campus Dr, Cary,NC 27513-2414. † 1 in�2.54 cm.











Tab

le3.

Ove

rall

Func

tiona

lCap

acity

(Con

tinuo

usSc

ale

Phys

ical

Func

tiona

lPer

form

ance

Test

[CS-

PFP]

),Ba

sic

Func

tiona

lAct

ivity

,Ba

lanc

e,an

dG

ait

Mea

sure

sPr

esen

ted

byH

oehn

and

Yahr

Stag

ean

dU

nifie

dPa

rkin

son’

sD

isea

seRa

ting

Scal

e(U

PDRS

)M

otor

Scor

e

Mea

sure

Ho

ehn

and

Yah

rSt

age

UP

DR

SM

oto

rSc

ore

1–1

.52

2.5

3Li

nea

rT

ren

dC

oh

enf

0–1

51

5.5

–30

30.5

–45

45.5

–60

Lin

ear

Tre

nd

Co

hen

f

CS-

PFP

tota

ln�

100

n�97

Mea

n62

.90

54.7

442

.44

28.6

7F

valu

e:33

.78

0.33

Mea

n59

.88

48.2

342

.61

20.9

3F

valu

e:23

.86

0.24

SD13

.40

12.7

616

.04

14.5

8P�

.000

1SD

11.5

015

.09

15.4

510

.21

P�.0

001

Min

50.2

029

.80

7.30

9.20

Min

42.3

017

.20

11.2

09.

20

Q1

52.3

047

.10

34.3

021

.90

Q1

49.8

037

.20

31.9

09.

20

Med

ian

58.2

756

.22

41.7

327

.13

Med

ian

56.2

948

.25

42.0

726

.55

Q3

72.9

061

.60

51.1

035

.60

Q3

71.4

059

.25

57.5

027

.10

Max

80.8

078

.20

73.7

057

.50

Max

80.8

078

.20

68.6

027

.10

CS-

PFP

RPE

n�10

0n�

97

Mea

n11

.811

.011

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.7F

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320.

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13.7

Fva

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5.94

0.05

SD1.

01.

91.

71.

5P�

.071

5SD

1.7

2.0

1.3

0.6

P�.0

168

Min

11.0

6.0

8.0

9.0

Min

8.0

6.0

9.0

13.0

Q1

11.0

10.0

11.0

13.0

Q1

10.0

10.0

11.0

13.0

Med

ian

11.5

11.0

12.0

13.0

Med

ian

11.0

11.5

12.0

14.0

Q1

12.5

12.0

13.0

13.0

Q3

13.0

13.0

13.0

14.0

Max

13.0

15.0

15.0

14.0

Max

14.0

15.0

15.0

14.0

FRT

(in)

n�15

2n�

97

Mea

n16

.07

14.2

812

.13

10.7

9F

valu

e:46

.00

0.30

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.96

13.1

511

.85

8.73

Fva

lue:

17.5

80.

17

SD1.

602.

582.

882.

95P�

.000

1SD

2.20

2.93

3.35

4.53

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001

Min

13.3

36.

706.

003.

50M

in10

.80

6.50

3.80

3.50

Q1

15.5

012

.70

10.3

09.

20Q

112

.70

11.2

510

.20

3.50

Med

ian

16.3

314

.40

12.2

011

.00

Med

ian

15.0

013

.50

11.3

011

.00

Q3

16.8

015

.80

14.0

012

.50

Q3

16.8

015

.70

14.2

011

.70

Max

18.2

019

.20

17.3

016

.70

Max

19.2

018

.20

18.5

011

.70

TUG

(s)

n�13

6n�

133

Mea

n8.

409.

2111

.18

10.8

9F

valu

e:10

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0.07

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n8.

789.

8510

.34

11.7

8F

valu

e:7.

770.

05

SD1.

152.

063.

783.

59P�

.001

5SD

1.05

2.27

2.95

3.52

P�.0

061

Min

6.61

5.54

7.48

6.21

Min

6.61

6.38

5.54

8.48

Q1

8.21

7.86

9.30

8.48

Q1

8.21

8.32

9.02

9.22

Med

ian

8.64

9.25

10.3

111

.13

Med

ian

8.80

9.48

9.83

11.6

6

Q3

8.82

9.97

11.6

712

.08

Q3

9.66

10.7

211

.41

12.0

8

Max

9.73

18.1

431

.57

20.9

2M

ax10

.61

17.7

220

.92

17.4

4

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tinue

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Tab

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Con

tinue

d Mea

sure

Ho

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and

Yah

rSt

age

UP

DR

SM

oto

rSc

ore

1–1

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2.5

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rT

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dC

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0–1

51

5.5

–30

30.5

–45

45.5

–60

Lin

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360°

turn

time,

wor

st(s

)n�

150

n�95

Mea

n3.

333.

914.

817.

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valu

e:45

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0.30

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054.

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245.

18F

valu

e:13

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0.14

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981.

371.

583.

60P�

.000

1SD

0.58

1.06

1.41

0.32

P�.0

003

Min

2.22

2.43

2.53

2.94

Min

2.22

2.45

2.59

4.95

Q1

2.90

3.03

3.74

5.26

Q1

2.55

3.32

3.07

4.95

Med

ian

3.11

3.62

4.68

6.87

Med

ian

2.90

3.82

3.86

5.18

Q3

3.51

4.18

5.67

8.42

Q3

3.61

4.44

4.93

5.40

Max

5.11

10.8

29.

5319

.82

Max

4.27

7.68

7.78

5.40

360°

turn

step

s,w

orst

n�15

0n�

95

Mea

n6.

337.

558.

6611

.04

Fva

lue:

38.4

20.

25M

ean

6.26

7.88

8.89

10.2

5F

valu

e:15

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0.15

SD0.

931.

962.

663.

61P�

.000

1SD

0.90

2.30

2.46

0.35

P�.0

002

Min

5.00

5.00

5.00

5.50

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5.00

5.50

5.50

10.0

0

Q1

5.50

6.00

7.00

8.50

Q1

5.50

6.50

7.50

10.1

3

Med

ian

6.50

7.00

8.00

10.7

5M

edia

n6.

007.

008.

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.25

Q3

6.88

8.00

9.50

12.0

0Q

37.

008.

6310

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10.5

0

Max

7.50

14.0

016

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24.5

0M

ax8.

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13.5

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6MW

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ce(m

)n�

150

n�97

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n57

9.02

545.

6046

0.24

397.

81F

valu

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0.33

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3.91

515.

5550

1.54

392.

33F

valu

e:9.

290.

09

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93.6

210

7.09

104.

02P�

.000

1SD

53.9

010

4.07

120.

1042

.76

P�.0

030

Min

511.

9030

7.24

175.

0020

9.70

Min

505.

4030

2.80

214.

6036

7.00

Q1

522.

6050

3.90

373.

1032

3.10

Q1

536.

2043

9.65

432.

2036

7.00

Med

ian

561.

9056

2.10

464.

2038

8.90

Med

ian

567.

6051

6.30

527.

4036

8.30

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629.

6060

5.60

534.

1047

1.15

Q3

598.

1059

9.45

605.

6044

1.70

Max

686.

2076

2.20

634.

1063

5.00

Max

686.

2076

2.20

651.

1044

1.70

6MW

Tga

itsp

eed

(m/s

)n�

150

n�97

Mea

n1.

611.

521.

281.

10F

valu

e:50

.49

0.33

Mea

n1.

591.

431.

391.

09F

valu

e:9.

290.

09

SD0.

200.

260.

300.

29P�

.000

1SD

0.15

0.29

0.33

0.12

P�.0

030

Min

1.42

0.85

0.49

0.58

Min

1.40

0.84

0.60

1.02

Q1

1.45

1.40

1.04

0.90

Q1

1.49

1.23

1.20

1.02

Med

ian

1.56

1.56

1.29

1.08

Med

ian

1.58

1.44

1.47

1.02

Q3

1.75

1.68

1.48

1.31

Q3

1.66

1.67

1.68

1.23

Max

1.91

2.12

1.76

1.76

Max

1.91

2.12

1.81

1.23

(Con

tinue

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Owner

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Tab

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Con

tinue

d Mea

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Ho

ehn

and

Yah

rSt

age

UP

DR

SM

oto

rSc

ore

1–1

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2.5

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ren

dC

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0–1

51

5.5

–30

30.5

–45

45.5

–60

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nd

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116

n�11

6

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7.65

160.

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8.10

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lue:

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90.

21M

ean

168.

8615

5.86

148.

2212

8.40

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lue:

4.94

0.03

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.24

32.3

341

.10

P�.0

001

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.70

38.6

736

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24.4

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100.

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3.50

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156.

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318

5.30

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9.50

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229.

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7.30

196.

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250.

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0.30

0.32

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0.84

0.93

0.43

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0.95

0.51

0.43

0.93

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1.23

1.18

0.73

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1.23

1.15

1.05

0.93

Med

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1.39

1.29

0.99

Med

ian

1.36

1.26

1.29

1.07

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1.55

1.48

1.30

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1.54

1.52

1.41

1.12

Max

1.91

2.39

1.63

Max

1.91

2.39

1.74

1.12

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(s)

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364.

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0.17

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0.67

1.38

1.53

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2.44

1.85

1.81

1.75

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1.85

1.75

1.81

2.68

Q1

2.73

2.41

3.31

3.47

Q1

2.41

2.59

2.37

4.22

Med

ian

2.96

2.81

4.52

4.80

Med

ian

2.72

3.16

3.20

4.50

Q3

4.47

3.81

5.41

8.39

Q3

2.97

3.84

4.67

5.65

Max

4.53

17.6

211

.53

19.7

1M

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539.

788.

6615

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(Con

tinue

d)




involved, with the biggest difference(more than 100 m) occurringbetween score categories of 30 to 45and 45 to 60. A similar pattern wasseen for the mean scores.

Data for the 2MWT (Tab. 3, Fig. 2,eFig. 2) were available only fromsamples collected at Boston Univer-sity and only for those in H&Y stages2, 2.5, and 3. The biggest drop indistance was seen between H&Ystages 2.5 and 3, with a mean differ-ence of about 49 m between partic-ipants who were least and mostinvolved. Findings were similar withrespect to the UPDRS motor scores.

Basic Functional ActivitiesFor the supine-to-stand task, themean time to complete the task wasnot substantially different until H&Ystage 2.5 or UPDRS motor score 45.5to 60 (Tab. 3; Fig. 3; eFig. 3, availableat ptjournal.apta.org). When examin-ing the supine-to-stand task by H&Ystage, the mean time to complete thetask appears to discriminate supine-to-stand times better than mediantimes. The mean and median timesfor the supine-to-stand task were sim-ilar for the UPDRS motor scores. Thepattern for stand to supine was sim-ilar to supine to stand, although thetrend was for the mean time to beconsistently slightly higher.

With respect to FAR, the mean andmedian values changed by approxi-mately 20 degrees between H&Ystages 1 and 3 (Tab. 3, Fig. 3, eFig. 3).The drop in mean FAR across UPDRSmotor scores was 36 degrees fromlowest to highest, with a similar pat-tern for median values.

DiscussionThese data provide expected rangesof physical function by disease sever-ity for measures commonly usedwith individuals in early and middlestages of PD. We chose these mea-sures because they capture many ofthe daily tasks that people with PDTa

ble

3.C

ontin

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sure

Ho

ehn

and

Yah

rSt

age

UP

DR

SM

oto

rSc

ore

1–1

.52

2.5

3Li

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51

5.5

–30

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45.5

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Lin

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(s)

n�18

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Mea

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417.

04F

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e:12

.89

0.09

SD0.

941.

821.

763.

47P�

.000

1SD

0.75

1.27

1.89

3.00

P�.0

005

Min

2.60

1.96

2.66

2.04

Min

2.34

1.96

2.03

2.91

Q1

3.60

3.04

3.87

4.46

Q1

3.11

3.15

3.00

5.84

Med

ian

4.31

3.54

4.77

5.20

Med

ian

3.47

3.94

4.35

6.72

Q3

4.80

4.58

5.98

8.44

Q3

3.91

4.69

5.15

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commonly bring to the attention oftheir health care providers, such asgetting in and out of bed, rising froma chair, walking, maintaining bal-ance, and turning to look behindwhile driving.

The data provide clinicians andresearchers with a context for inter-preting functional limitations of peo-ple with PD. Clinicians also can usethe data to identify individuals whoperform outside of anticipated meanand median scores for specific tasks.Furthermore, these data can informdecisions regarding appropriate mea-sures for future studies of physicalintervention.

We described the data in relation to2 different measures typically usedto characterize PD severity: theUPDRS motor score and the modi-fied H&Y scale.6 The UPDRS is thegold standard for experimental stud-ies and medical management; how-ever, extensive training is requiredto use this measure appropriately, itis time intensive, and the scope ofinformation gathered is beyond thatrequired for decisions related tophysical intervention. In contrast,the H&Y score provides only acoarse estimate of disease progres-sion but is more accessible to physi-cal therapists. For these reasons, wechose to examine physical activitiesin relation to both measures.

Several insights related to the level ofdisease severity at which functionaldecline begins to emerge, choice ofmeasures at different points in thedisease course, and interpretation ofmeasures emerged from this work.The first insight is that activity limi-tations occur very early in PD, asindicated by the CS-PFP, becomingprogressively worse as the diseaseadvances. This finding is of impor-tance because most measures usedwith people who have PD are not asclearly responsive to early limitationsin activities as is the CS-PFP.

Individuals with PD had lowerCS-PFP scores compared with indi-viduals who were healthy in thestudy by Cress and Meyer.22 Thesescores represent a substantial loss offunctional capacity. Those individu-als with H&Y stage 3 scores (meanage�69 years) had CS-PFP scoresbelow 30, more than 25 points lowerthan scores of individuals who werehealthy, indicating even greater lossof capacity.

The CS-PFP is a unique measurebecause it quantifies capacity forperformance of daily functionalactivities.22 As such, this test is morelikely to identify limitations thatwould be missed in performance of afew single tasks such as those typi-cally used to quantify function (eg,FRT, TUG). Furthermore, the tasksincluded in the CS-PFP encompass abroad range of activities required fordaily function.

Data from a variety of studies suggestthat transition from independence todependence occurs around a CS-PFPscore of 57.22 As evidenced bymedian scores, a substantial number

of participants in our data set hadreached or exceeded this thresholdby H&Y stage 2.5 and UPDRS motorscore of 30.5 to 45. These findingsare consistent with data of Shulmanand colleagues1 indicating a transi-tion from preclinical disability anddisability occurs for people withUPDRS total scores above 50.

It should be noted that the transitionto disability specific to people withPD has not yet been established.Because time to complete tasks isimportant in scoring the CS-PFP, bra-dykinesia probably affects the overallscores substantially, bringing individ-uals to the transition point (score of57) established for older adults, eventhough they may not be approachingdisability. Nevertheless, these dataunderscore the degree to which PDaffects overall physical capacity evenvery early in the disorder.

Of interest, most of these individualscontinue to perform within a rela-tively constant rate of perceivedexertion as evidenced by their RPEof �12, consistent with the rangeobserved in older adults who are

Figure 1.Continuous Scale Physical Functional Performance Test (CS-PFP) score distribution byUnified Parkinson’s Disease Rating Scale (UPDRS) motor scores. Box plot symbols:asterisk indicates outliers beyond 3 standard deviations from the mean score; diamondrepresents mean score; dark gray box represents distance between first quartile andmedian; and light gray box represents distance between median and third quartile.




Figure 2.Balance and gait measure score distributions by Unified Parkinson’s Disease Rating Scale (UPDRS) motor scores. 6MWT�Six-MinuteWalk Test, 2MWT�Two-Minute Walk Test, FRT�Functional Reach Test, TUG�Timed “Up & Go” Test. Box plot symbols: asteriskindicates outliers beyond 3 standard deviations from the mean score; diamond represents mean score; dark gray box representsdistance between first quartile and median; and light gray box represents distance between median and third quartile.




healthy. These findings suggest thatpeople with PD adjust task perfor-mance to stay in the comfortablerange. Only those individuals athigher levels of disease severityreported a high RPE during the rela-tively common functional activitiesof the CS-PFP. For example, thegroup with UPDRS motor scores of45.5 to 60 had a mean RPE of 13.7(SD�0.6), underscoring the degreeof effort required for relatively sim-ple tasks.

The only other measure in this studythat detected losses early was theFAR. The mean FAR was 107 degrees(SD�8.6) for participants in H&Ystages 1 and 1.5 (mean age�55years, SD�8.5). These individualshad substantially reduced FAR com-pared with a sample of adults with-out PD in which the mean FAR was117.9 degrees (SD�14.2) for menand 127.8 degrees (SD�10.4) forwomen (data from 40 adults whowere healthy, aged 40–59 years,55% female), (unpublished data). ByH&Y stage 3 (mean age�69 years,

SD�8.0), participants were 30degrees below the expected valuesfor individuals of similar age who arehealthy. These findings have impor-tant implications for balance andfunction. Axial rotation is used tomaximize FRT distance38; thus, it islikely that the substantially lowerFAR for participants in H&Y stage 3contributes to balance dysfunctionin later stages of PD. Furthermore,limited ability to twist the torso tosee behind has ramifications for anyactivity that requires such motions(eg, reaching for objects, turning tosee while backing up a car).

Two other measures (FRT and6MWT) showed a systematicdecrease in values across stages ofPD, although they did not detectdecline in the participants with earlysigns of PD. Participants in the earli-est stages of PD demonstrated anage-appropriate median FRT score(15–16 in), whereas those withUPDRS motor scores of 30 to 45 andH&Y stage 3 had a median reach of11.3 in. The difference between

H&Y stages approached 2 in. To putthese data into context, Dibble andLange39 recommended a cutoff of12.5 in in patients with PD to predictfalls (sensitivity�86%). In our sam-ple, the following percentages ofparticipants were below this cut-point: H&Y stage 2�11.0%, H&Ystage 2.5�51.0%, and H&Y stage3�70.3%. These results are consis-tent with those of Tanji et al,40 whoalso found the FRT able to distin-guish between those with posturalinstability (H&Y stages 2.5 and 3)and those without postural instabil-ity (H&Y stage 2).

With respect to the 6MWT, the meanwalk distances in our sample for par-ticipants who were least involved(H&Y stages 1–2, UPDRS motorscores�0–15) appear appropriatecompared to normative values forpeople who are healthy.33 A differ-ence in mean values of nearly 200 mwas observed across each UPDRSmotor grouping. Our findings areconsistent with those of otherauthors.34,41,42 In the context of gait

Figure 3.Supine-to-stand test and functional axial rotation (FAR) (worst side only) score distribution by Unified Parkinson’s Disease Rating Scale(UPDRS) motor scores. Box plot symbols: asterisk indicates outliers beyond 3 standard deviations from the mean score; diamondrepresents mean score; dark gray box represents distance between first quartile and median; and light gray box represents distancebetween median and third quartile.




speed, Perry and colleagues43 indi-cated that 0.8 m/s is a cutpointbetween community ambulation andlimited community ambulation forpeople recovering from a stroke,whereas Studenski and colleagues44

found 1.0 m/s to be a cutpoint forpredicting decline in health statusand function for older adults. Thegroups of participants in our studywith H&Y stage 3 and UPDRS motorscores of 45.5 to 60 had mean andmedian gait speeds (around 1.0 m/s)at or near values indicating higherrisk of health problems and func-tional compromise.

A second important insight is thatthe following measures begin toshow impairment relatively later indisease progression, beginning inH&Y stage 3: 2MWT, TUG, supine-to-stand test, and stand-to-supinetest. Both mean and median scoressuggest substantial difficulty for peo-ple later in the disorder. The dataindicate that the 2MWT, in contrastto the 6MWT, is not of sufficientlength to pick up the enduranceproblems in individuals who are inthe earlier stages of PD,45 eventhough deficits in economy of move-ment have been established for thosein very early stages of PD.46

For the TUG, scores of 10 seconds orless are generally considered normalin elderly people who are healthy.11

Whether examining the mean or themedian in our sample, there was atransition from scores below 10 sec-onds for participants who were lessinvolved (H&Y stages 1, 1.5, and2) to scores above 10 seconds forthose in H&Y stages 2.5 and 3. Theminimum score was 5.5 seconds,and the maximum score was 31.6seconds. Only 22.5% of participantsin H&Y stages 1, 1.5, and 2 hadscores above 10 seconds for theTUG, whereas 53.8% of participantsin H&Y stages 2.5 and 3 had scoresabove 10 seconds. With respect toUPDRS motor scores, the transition

from below to above 10 secondsoccurred at UPDRS scores of 30 of45 points for the mean (10.3 sec-onds) and was similar for the median(9.8 seconds). These findings sug-gest that limitations in the TUG arenot revealed until later in the diseaseprogression. These findings are sup-ported by Ellis and colleagues,45 whoreported mean TUG scores of 55 sec-onds in a sample of patients with PDwho were predominantly (64%) inH&Y stage 4.

The stand-to-supine and supine-to-stand tests can be important practi-cal measures, as complaints of diffi-culty moving in bed are commonamong people with PD. In this study,it was only in H&Y stage 3 or UPDRSmotor scores above 45 that thesetests revealed limitations. These par-ticipants were twice as slow as indi-viduals in the early stages, althoughthe variability was large, suggestingthat not all participants in H&Y stage3 will demonstrate limitations in thisarea.

A third insight relates to the consid-erable heterogeneity and variance inperformance observed in our sam-ple, particularly in the later stages ofPD. Given this variability, individualsat either end of the measurementscale can skew the mean substan-tially. For some measures (eg,supine-to-stand task, 360° turn), themedians indicated much greaterfunctional limitations than themeans. Based on our findings, wesuggest examining both the meanand median scores. In addition, dis-tinguishing differences in physicalfunction by stage of disease alonemay not be sufficient. Examinationof subpopulations may yield less vari-ability and more narrow profiles. Forexample, categorizing by dominanceof symptom (eg, postural instabilitygait difficulty or tremor dominant)may reveal very different functionaltrajectories and should be investi-gated in future studies.

The fourth important point relates toclinical and research recommenda-tions for selection of functional mea-sures across stages of PD. Choice ofmeasures will necessarily be dictatedby the purpose for which they are tobe used. In the clinic, physical ther-apists managing patients in the earlystages may consider using the CS-PFPand the FAR to identify deficits instatus. The 6MWT and the FRT alsocould be incorporated early in thedisease to establish baseline statusand repeated periodically thereafterto determine performance relative toelderly people who are healthy andto expected ranges in PD. The TUG,2MWT, and supine-to-stand measureshould be reserved for patients in themoderate stages.

For intervention studies, choice ofmeasures should be determined byboth stage of PD and study length.For participants in the earliest stageof PD, only the CS-PFP and FARdetected differences from age-appropriate norms. Thus, for suchparticipants, these 2 measures havepotential to detect change of func-tional problems in short-term studies(less than 6 months). Conversely,other measures have low potential todetect functional problems in short-term studies in which participantsare in early stages of PD. Because ofthe lack of responsiveness of mostmeasures for people in the earlieststages of PD, a new measure of func-tion, the instrumented Timed “Up &Go” Test (iTUG),47 has been devel-oped. The iTUG appears to be espe-cially sensitive to deficits in balanceand may provide further insight intothese deficits in the earliest stages ofPD.

Many of the measures in addition tothe CS-PFP and FAR might be appro-priate for longer-term studies (eg,12–24 months), even when peoplein early stages of PD are included.Examples of such measures are theFRT and 6MWT, which could add




insight into functional change as thedisease progresses. The TUG,2MWT, and supine-to-stand measurewould be appropriate for studiesincluding participants who havemoderate to severe PD either at base-line or at the end of the study.

Several limitations should beacknowledged. First, most of the par-ticipants in this database were inH&Y stages 2, 2.5, and 3, with only3% in stages 1 to 1.5. These findingswere in part because people are notalways diagnosed in the earlieststages of PD, and of those who are,not all are referred for exercise inter-ventions. Second, because these dataare cross-sectional (not longitudi-nal), we cannot make statementsabout change over time. Neverthe-less, these data give some insightinto what to expect at each point inthe disease process and can helpclinicians determine which deficitsbegin in the earliest stages as well aswhich measures might be of mostuse early in the disease process.Future investigations, utilizingchange scores will be essential tofurther our understanding of perfor-mance in people with PD. Third,these data were derived from 5 dif-ferent studies, and not all measureswere performed at all sites and for allstudies. Nevertheless, the samplewas of sufficient size that the num-ber of participants ranged between100 and 252 for all measures. Finally,the participants were predominantlyeducated and white, with low diver-sity with respect to income and race,limiting ability to generalize to someextent. However the samples wererecruited from 3 distinct locationsacross the United States, increasinggeneralizability from a geographicalperspective.

In summary, typical values are pre-sented relative to disease severity forstandard measures of functional abil-ity commonly used by researchersand clinicians who work with indi-

viduals in early and mid stages of PD.Findings demonstrate that functionalloss occurs at different points in thedisease process, depending on thetask under consideration. The result-ing profile of functional limitationsprovides benchmarks that cliniciansand researchers can use to interpretand monitor status of patients.

Dr Schenkman, Dr Ellis, Dr Christiansen, DrTickle-Degnen, and Dr Wagenaar providedconcept/idea/research design. All authorsprovided writing. Dr Ellis, Dr Christiansen, DrTickle-Degnen, and Dr Hall provided datacollection. Dr Schenkman, Dr Christiansen,Dr Baron, and Dr Tickle-Degnen provideddata analysis. Dr Schenkman and Dr Ellisprovided project management and institu-tional liaisons. Dr Schenkman, Dr Tickle-Degnen, and Dr Wagenaar provided fundprocurement. Dr Schenkman, Dr Ellis, DrTickle-Degnen, and Dr Hall provided partic-ipants. Dr Schenkman provided facilities/equipment. Dr Ellis, Dr Tickle-Degnen, DrHall, and Dr Wagenaar provided consulta-tion (including review of manuscript beforesubmission).

The parent studies from which data wereobtained for this study were approved by theinstitutional review boards of Boston Univer-sity, Duke University, and the University ofColorado.

This work was supported by National Institutesof Health grants R01 HD043770-04, MO1RR00051, 5-P60-11268, and NAG21152.

DOI: 10.2522/ptj.20100236

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doi: 10.2522/ptj.20100236Originally published online July 21, 2011

2011; 91:1339-1354.PHYS THER. and Robert WagenaarAnna E. Barón, Linda Tickle-Degnen, Deborah A. Hall Margaret Schenkman, Terry Ellis, Cory Christiansen,Middle-Stage Parkinson DiseasePerformance Among People With Early- and Profile of Functional Limitations and Task

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