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Prevalence and Outcomes of Low Mobility in HospitalizedOlder Patients
Cynthia J. Brown, MD,�w Rebecca J. Friedkin, PhD,z and Sharon K. Inouye, MD, MPH,z
OBJECTIVES: To estimate the prevalence of different lev-els of mobility in a hospitalized older cohort, to measure thedegree and rate of adverse outcomes associated with dif-ferent mobility levels, and to examine the physician activityorders and documented reasons for bedrest in the lowestmobility group.
DESIGN: A prospective cohort study.
SETTING: An 800-bed university teaching hospital.
PARTICIPANTS: Four hundred ninety-eight hospitalizedmedical patients, aged 70 and older.
MEASUREMENTS: Using average mobility level, scoredfrom 0 to 12, the low-mobility group was defined as havinga score of 4 or less, intermediate as a score of higher than 4to 8, and high as higher than 8. Outcomes were functionaldecline, new institutionalization, death, and death or newinstitutionalization.
RESULTS: Low and intermediate levels of mobility werecommon, accounting for 80 (16%) and 157 (32%) studypatients, respectively. Overall, any activity of daily living(ADL) decline occurred in 29%, new institutionalization in13%, death in 7%, and death or new institutionalization in22% of patients in this cohort. When compared with thehigh mobility group, the low and intermediate groups wereassociated with the adverse outcomes in a graded fashion,even after controlling for multiple confounders. The low-mobility group had an adjusted odds ratio (OR) of 5.6(95% confidence interval (CI)52.9–11.0) for ADL decline,6.0 (95% CI52.5–14.8) for new institutionalization, 34.3(95% CI56.3–185.9) for death, and 7.2 (95% CI5 3.6–
14.4) for death or new institutionalization. The intermedi-ate group had adjusted ORs of 2.5 (95% CI5 1.5–4.1), 2.9(95% CI5 1.4–6.0), 10.1 (95% CI51.9–52.9), and 3.3(95% CI51.8–5.9) for ADL decline, new institutionaliza-tion, death, and death or new institutionalization, respec-tively. Bedrest was ordered at some point duringhospitalization in 165 (33%) patients. For most patients,mobility was limited involuntarily (bedrest orders), and al-most 60% of bedrest episodes in the lowest mobility grouphad no documented medical indication.
CONCLUSION: Lowmobility and bedrest are common inhospitalized older patients and are important predictors ofadverse outcomes. This study demonstrated that the ad-verse outcomes associated with low mobility and bedrestmay be viewed as iatrogenic events leading to complica-tions, such as functional decline. J AmGeriatr Soc 52:1263–1270, 2004.
Key words: mobility; bedrest; hospital complications;geriatrics; iatrogenesis
Low mobility and bedrest are common occurrences dur-ing hospitalization. One study found that older patients
were documented to be on bedrest for 23% of 3,500 pa-tient-days studied.1 Another study found that 33% of olderhospitalized patients were confined to bed or chair duringthree separate survey days.2 One report noted that 65% ofpatients experienced a decline in mobility from their pre-admission baseline to the second hospital day, with mostpatients failing to improve by discharge.3 These studiesconstitute the body of literature on the prevalence of lowmobility and bedrest in hospitalized patients, yet none ofthe studies have examined mobility and associated adverseoutcomes throughout the entire hospital course.
Hospitalization has been shown to be associated withadverse outcomes such as high rates of functional disability,increased lengths of stay, and increased likelihood of nurs-ing home placement upon discharge.4,5 One study foundolder patients to be more at risk for medical and iatrogeniccomplications during hospitalization,6 which may contrib-ute to these adverse outcomes. It has also been suggestedthat use of bedrest during hospitalization may be more
Address correspondence to Cynthia J. Brown, MD, The University ofAlabama at Birmingham, VAMC GRECC 11G Room 8225, 1530 3rdStreet South, Birmingham AL 35294. E-mail: [email protected]
This work was supported in part by grants from the National Institute onAging (T32AG1934, R01AG12551, and K24AG00949). Dr. Brown wassupported by a training grant from the National Institute on Aging(T32AG1934) and is a recipient of a John A. Hartford Foundation/AmericanFederation for Aging Research Academic Geriatrics Fellowship ProgramAward (R04191). Dr. Inouye is a recipient of a Mid-career Award from theNational Institute on Aging (K24AG00949) and a Donaghue InvestigatorAward from the Patrick and Catherine Weldon Donaghue Medical ResearchFoundation (DF98-105).
From the �Birmingham/Atlanta Veterans Affairs Geriatric Research, Educa-tion, and Clinical Center, Birmingham, Alabama; wDepartment of Medicine,Division of Gerontology and Geriatric Medicine, University of Alabama atBirmingham, Birmingham, Alabama, and zDepartment of Medicine, YaleUniversity School of Medicine, New Haven, Connecticut.
JAGS 52:1263–1270, 2004r 2004 by the American Geriatrics Society 0002-8614/04/$15.00
related to aspects of hospital care such as restraint use andimmobilizing devices than the patient’s admitting diagno-sis.5,7 Previous literature reviews have hypothesized a linkbetween low mobility during hospitalization and adverseoutcomes through a variety of pathophysiological mecha-nisms,8–10 but these theoretical mechanisms are not basedon actual evidence in any population. The rates of adverseoutcomes associated with different mobility levels duringhospitalization have not been previously described.
The objectives of the present study were to estimate theprevalence of different levels of mobility in a hospitalizedolder cohort; to measure the degree and rate of adverseoutcomes, including functional decline, new institutional-ization, death, and death or new institutionalization, asso-ciated with different mobility levels during hospitalization;and to examine the physician activity orders and the doc-umented reasons for bedrest in the lowest mobility group.
METHODS
Setting and Patients
Initial data collection was conducted from November 1989to July 1991 as part of a prospective cohort study of olderhospitalized patients described previously.11 In brief, po-tential participants were patients aged 70 and older con-secutively admitted to the medicine service at Yale–NewHaven Hospital, an 800-bed urban teaching hospital serv-ing a large community as well as a referral population. Ofthe 525 subjects enrolled in the previous study, with exclu-sion criteria previously described,11 patients with a lengthof stay of 2 nights or less were further excluded because ofinsufficient time to develop the effects of low mobility(n5 22), as were those whose disposition was unknown(n5 5). The final cohort for this study included 498 pa-tients.
Informed consent for participation was obtained ver-bally from the patients or, for those with substantial cog-nitive impairment, from a surrogate (usually the closestrelative or legal guardian), according to procedures ap-proved by the institutional review board of Yale UniversitySchool of Medicine.
Assessments
Experienced clinical researchers who underwent intensivetraining and interrater reliability assessments and wereblinded to the research questions and hypotheses of thepresent study conducted assessments. The patient, primarynurse, and family underwent structured baseline interviewsduring the initial 48 hours of the hospital stay. The baselinepatient interview included demographics, self-reportedphysical function 2 weeks before admission,12 and theMini-Mental State Examination (MMSE).13 The baselinenurse interview included a rating for seven basic activities ofdaily living (ADLs) (feeding, bathing, grooming, dressing,toileting, walking, and transferring) upon admission to thehospital. Nurses were asked whether the patient was inde-pendent, required some assistance, or required total assis-tance with each ADL. The family interview included themodified Blessed Dementia Rating Scale (mBDRS)14,15 toevaluate for the presence of dementia at baseline. Medicalrecords were extracted for admission data needed to cal-
culate the Acute Physiology, Age, and Chronic Health Eval-uation (APACHE) II score;16 the Charlson ComorbidityIndex;17 whether there was an intensive care unit (ICU) orcoronary care unit (CCU) stay; and discharge destination ordeath.
After the baseline interview, the primary nurses wereinterviewed on alternate days and asked to rate the patients’ADLs and mobility during the previous 24-hour period,based on their own observations and nursing shift reports.Mobility during the previous 24 hours was assessed byasking the nurse the number of times per day (up to a max-imum of five) the patient was up in a chair or walking andthe degree of assistance required. All mobility episodes ofany type (physical therapy, family initiated, or patient self-mobilization) were captured and included in the nursingreported outcome. Nurses were also asked whether the pa-tient had been on total bedrest for any reason during theprevious 24 hours. In most cases, the patient’s primarynurse was interviewed. The final nurse interview was sched-uled as close to discharge as possible. Because the goal wasto determine the effects of the patient’s actual mobility levelin the hospital, the observed mobility level (as reported bythe nurses), rather than patient physical performance ca-pacity, was used. Nurse’s ratings were used because ob-server-rated ADLs were considered to be more accuratethan patient self-reports18,19 and have been used in previousstudies as the reference standard.20 The nurses were to bethe preferred observers in the hospital setting, because theyspend the most time with patients and are familiar withpatients’ mobility level.
Rating of Mobility
Detailed nursing observations were available regardingdegree of assistance required and number of times patientstransferred and ambulated during the previous 24-hourperiod. In an effort to capture the clinical richness of thisdata, an empiric scoring system was developed, assigningpoints from 0 to 12 for increasing levels of mobility, asfollows. Bedrest was assigned a score of 0. Transferringfrom bed to chair once was assigned a score of 2; transfer-ring two or more times, a score of 4. Ambulation once withtotal assistance was assigned a score of 6; two or more timeswith total assistance or once with partial or no assistance, ascore of 8; two ormore times with partial assistance, a scoreof 10; and independent ambulation two or more times perday, a score of 12.
Before analysis, various ways of characterizing mobil-ity were considered, because there was great day-to-dayvariability in the level of mobility for a given patient.Measures such as number of days on bedrest or highest levelof mobility attained were considered, but these limitedmeasures would misclassify many patients. For example, ameasure based on days of bedrest would not capture pa-tients with limited mobility who were not on bedrest. Ameasure based on highest degree of mobility attained wouldnot distinguish between those who walked daily and thosewho remained in bed throughout the majority of their hos-pital stay, then ambulated just before discharge. To create ameasure that characterized the overall degree of mobilityacross the entire hospitalization, an average of all mobilityobservations for each patient was used. Using the average
1264 BROWN ET AL. AUGUST 2004–VOL. 52, NO. 8 JAGS
score allowed for the capture of mobility levels over theentire hospital course and the ability to take into account allobservations.
To maintain an ordinal rating of overall mobility, theaverage score was trichotomized into three mobility groups:low, intermediate, and high. Because the hypothesis wasthat ambulation was the key to maintenance of functionduring hospitalization, low mobility was defined a priori ashaving an average mobility level of bedrest or bed to chairfor the entire hospitalization. This coincides with an aver-age mobility rating of 4 or less. Having an average mobilityrating of greater than 4 to 8 was defined as intermediatemobility, which, on average, coincides with ambulation oneor two times with total assistance. An average mobilityrating of greater than 8 was defined as high mobility, whichcoincides, on average, with ambulation two or more timeswith partial or no assistance. In addition, bedrest was de-fined as not walking or transferring for the previous 24hours.
Outcomes
The primary outcome was functional decline during hos-pitalization, defined as a decline in any of five nonmobilityADLs (bathing, dressing, grooming, toileting, and feeding)from admission to discharge, as rated by the nurses. Twen-ty-four patients who were completely impaired in all ADLsupon admission were excluded from analysis of this out-come, because further decline was not possible, leaving 474patients for the primary outcome. For patients who diedduring hospitalization, the last available nursing observa-tion for ADLs was used. Terminally ill patients were in-cluded in these analyses because of the high variability ofmobility levels for these patients and to minimize survivalbias. Of the 33 patients who died during the study, 14(42%) had intermediate or high levels of mobility just be-fore their death; this pattern of variability has also beendocumented in recent studies.21
Secondary outcomes were new institutionalization,death during hospitalization, and death or new institution-alization. New institutionalization was defined as place-ment of a surviving community-dwelling person in anursing home or a rehabilitation facility at discharge(n5434). This outcome definition excluded 31 patientsadmitted from an institution. Dying patients were not in-cluded in the new institutionalization outcome. The com-bined outcome of death or new institutionalization wasincluded to avoid potential inferential errors that mightarise because patients who die can no longer be dischargedto an institution.
Other Study Variables
Definitions and cutpoints for study variables were selectedbased on clinically meaningful thresholds, previously pub-lished studies, and distributions of the variables in the studypopulation. Dementia was defined based on previous stud-ies as duration of cognitive symptoms of at least 6 monthsand (1) mBDRS greater than 4 or (2) mBDRS greater than 2and MMSE less than 20.11 Older age was defined as age 80and older based on previous studies and a distribution rep-resenting 50% of the sample. For the APACHE II score, thecutpoint of 16 was selected to indicate a high level of ill-
ness severity based on previous studies.5,7,11 For the Charl-son index, which has been used to assess the effect ofcomorbidity in many studies examining various healthoutcomes,22–26 a score of 3 or greater was selected toindicate a high level of comorbidity based on previousstudies17 and the sample distribution (47% had a score of�3). ICU/CCU stay was defined as the patient having beenin the ICU or CCU at any time during the hospitalization.Nursing observations of mobility were not conducted in theICU or CCU.
Chart Review for Patients with LowMobility: Orders andReasons
To examine the reasons for low mobility during hos-pitalization and to determine whether low mobility wasmedically necessary, the most extreme formFcompletebedrestFwhere it was anticipated that documentationwould be best, was examined. Charts were reviewed for the66 patients in the lowest mobility group who had at leastone bedrest episode during hospitalization. Each bedrestobservation was examined as a separate event. For eachevent, the chart was reviewed for the 48 hours before andincluding the index date. The precise nature of the physi-cian’s activity orders (e.g., bedrest, out of bed, or ambula-tion orders), or the absence of any such orders on the date(s)of bedrest, were recorded, as were any documented reasonsfor bedrest by any member of the healthcare team. Med-ically accepted reasons for bedrest were derived from a re-view of the medical literature and expert opinion.27 Theresearch team (CJB, SKI) recorded, reviewed, and catego-rized additional reasons cited by any healthcare provider.
Statistical Analysis
The characteristics of the study group were described withappropriate descriptive statistics, and the proportion ineach mobility group (low, intermediate, and high) was de-termined. The relationship between mobility level and eachstudy outcome was examined in bivariate analyses, yieldingcrude relative risks (RRs) and associated 95% confidenceintervals (CIs). To investigate the relationship between mo-bility level and indicators of illness severity (APACHE II,Charlson index, and ICU or CCU stay), bivariate analysesof the relationship between mobility level and adverse out-come (always comparing the lower mobility group onlywith the most mobile group) were conducted, stratified bylevels of each of the three illness severity variables. If mo-bility level was functioning primarily as a marker for illnessseverity, the relationship between mobility and adverseoutcome would be expected to be stronger in the groupsdefined as more seriously ill.
Subsequently, the independent contribution of mobilitylevels to the adverse outcomes were explored in a series ofmultivariate logistic regression models, which sequentiallyadjusted for factors considered to be important covariables,including preadmission ADL impairment, demographics,and burden of illness indicators. The highest mobility cat-egory was used as the reference group in the logisticregression models. Collinearity was examined betweenpotential interrelated variables using appropriate correla-tion coefficients before inclusion in the multivariable mod-els. Analyses were performed using SAS, version 8 (SAS
PREVALENCE AND OUTCOMES OF LOW MOBILITY 1265JAGS AUGUST 2004–VOL. 52, NO. 8
Institute, Inc., Cary, NC), and Po.05 was considered toindicate statistical significance.
RESULTS
Characteristics of the cohort are shown in Table 1. Overall,the group had a mean age � standard deviation of78.7 � 6.1, 19% required assistance with two or moreADLs before admission, and 8% were admitted from anursing or convalescent home. Mean APACHE II andCharlson scores upon admission (15.0 � 3.7 and 2.9 � 2.2,respectively) indicated that the group had, on average, atleast a moderate degree of illness severity and comorbidity.The median length of stay was 8 days, with a range of 3 to79 days.
There were 2,318 nursing observations on the 498study patients, an average of 4.7 � 2.4 observations perpatient, with a range from two to 16. The mean mobilityrating for the 498 patients was 8.0 � 3.4, with a range fromzero to 12.
Low mobility levels during hospitalization were pre-sent in 80 (16%) patients. Intermediate mobility levelscharacterized the hospital stay for 157 (32%) patients, andthe remaining 261 (52%) patients had high mobility levels.Bedrest was noted for 14% of the daily nursing observa-tions and was present at some point during the hospitali-zation for 33% of patients, twice as many as were classifiedas having a low mobility level throughout their hospitalstay.
Adverse outcomes developed in a substantial propor-tion of the patients in the cohort. Of the 474 patients notrequiring total assistance with basic ADLs at their admis-sion interview, 135 (29%) experienced a new decline in
nonmobility ADLs at discharge, with 14% declining in oneADL, 7% declining in two ADLs, and 8% declining in threeor more ADLs at discharge. Of the 434 patients who sur-vived the hospitalization and were not admitted from aninstitution, 55 (13%) were newly discharged to an institu-tional setting. Thirty-three (7%) died in the hospital, and107 (22%) died or were newly discharged to an institution.
Figure 1 presents outcome rates at discharge for thethree levels of mobility. The results demonstrate a directlygraded relationship with the level of mobility being in-versely correlated with the rate of all adverse outcomes(Ptrendo.001).
Table 2 presents the associated crude (unadjusted) rel-ative risks and CIs from bivariate analyses. In each case, theresults demonstrate that low and intermediate mobility, incontrast to high mobility, was strongly and significantlyassociated with decline in any ADL, new institutionaliza-tion, death, and death or new institutionalization.
A primary concern during the analysis was to measurethe effects of low mobility independent of related factorssuch as severity of illness. The collinearity of average mo-bility level and the severity of illness measures (APACHE II,Charlson index, and ICU/CCU stay) was examined, and itwas found that the variables were somewhat correlated(absolute correlation coefficients 0.10–0.22) but not to thedegree to preclude their inclusion in multivariate analysis.
To clarify the relationship between mobility levels, in-dicators of illness severity, and adverse outcomes, bivariateanalyses stratified by dichotomous categories of APACHEII, Charlson index, and ICU/CCU stay were performed.These analyses (not shown) demonstrate significant effectsof low and intermediate mobility on each of the study out-comes within each illness stratum. Moreover, the magni-tude of the relationship between mobility level and adverseoutcome was generally comparable within each illness-
Table 1. Characteristics of Study Population (N5498)
Feature Value
Age, mean � SD 78.7 � 6.1Male, n (%) 219 (44)White, n (%) 451 (91)Married, n (%) 230 (46)Highest grade completed,
mean � SD�11.3 � 3.5
Living alone, n (%)� 164 (33)Admitted from an
institution, n (%)w38 (8)
Dementia at baseline, n (%)�z 83 (17)APACHE II score on
admission, mean � SD�15.0 � 3.7
Charlson Comorbidity Index scoreupon admission, mean � SD�
2.9 � 2.2
Preadmission activity of dailyliving impairment, n (%)z
95 (19)
Length of stay, days,median (range)
8 (3–79)
�Missing data: education, n57; living alone, n51; demented at baseline,n5 8; Acute Physiology, Age, and Chronic Health Evaluation (APACHE) II,n5 4; Charlson Comorbidity Index, n5 1.w Institution5 skilled nursing facility, rest home or convalescent home.z See text for definitions.SD5 standard deviation.
Figure 1. Graded relationship between mobility level and ad-verse outcome. For each adverse outcome, the dark bar corre-sponds to a low level of mobility (mobility rating 4), the checkedbar to an intermediate level (44–8), and the light bar to a highlevel (rating 48) (Ptrendo.001).
1266 BROWN ET AL. AUGUST 2004–VOL. 52, NO. 8 JAGS
severity stratum, as indicated by the Breslow-Day test forhomogeneity of the odds ratios.
Table 3 presents the independent contribution of mo-bility level to each of the adverse outcomes and the effects ofadding important covariables to the models in a sequentialfashion. These models demonstrate a consistently strongand statistically significant effect of limited mobility on theadverse outcomes of functional decline (new institutional-ization, death, and death or new institutionalization), evenafter adjustment for many covariates. The level of mobilitywas inversely correlated with the rate of each adverse out-come, and this significant graded relationship persistedeven after controlling for all covariates. For the primaryoutcome, functional decline during hospitalization, patientswith low mobility were 5.6 times more likely than thosewith high mobility to experience functional decline (95%CI52.9–11.0). Those with intermediate mobility were 2.5times more likely than those with high mobility to experi-ence functional decline (95% CI5 1.5–4.1). In the finalmodels, the covariates retaining a statistically significanteffect on adverse outcomes were APACHE II (for all out-comes), having an ICU/CCU stay (for all outcomes exceptnew institutionalization), Charlson index (for functionaldecline and death only), and preadmission ADL impair-ment (for all outcomes except death).
When baseline institutional status and length of staywere added to the model for the primary outcome (func-tional decline), neither was statistically significant, and eachchanged the model coefficients only modestly. The mobilityvariables retained their statistical significance. Given theseresults, institutional status and length of stay were not in-cluded in the final models shown (Table 3).
Terminally ill patients were included in these analyses,other than new institutionalization, with rationale providedin the Outcomes section, but when the 11 patients admittedfor terminal care were excluded from the analyses, mobilitywas still independently associated with all adverse out-comes.
Eighty patients (16%) were classified as having lowmobility over the course of their hospital stay according tothe study definition. Of these 80 patients, 66 (83%) were oncomplete bedrest for at least 24 hours during hospitaliza-tion. Table 4 presents the documented reasons for completebedrest extracted from medical records of the 66 low-mo-bility patients. Almost 60% of the observations had nodocumented medical reason for the bedrest. Patient refusalwas documented as a reason for bedrest for only nine (5%)
of the 176 observations. Physician’s orders for bedrest werepresent on the date of bedrest for only 92 (52%) of the 176observations.
DISCUSSION
Low mobility levels and complete bedrest episodes arecommon in hospitalized older persons, occurring in 16%and 33%, respectively, of patients in this study. Moreover,low mobility is an independent predictor of poor hospitaloutcomes at discharge, specifically decline in ADLs, newinstitutionalization, and death. The contribution of lowmobility to these outcomes remained statistically significantin multivariate analyses even after controlling for pre-admission ADL impairment, age, sex, marital status, illnessseverity, and comorbidity. Mobility ratings were also cor-related with all adverse outcomes in a graded fashion, lend-ing support to the idea of the direct relationship betweenmobility level and adverse outcomes. Chart review indicatesthat patients are frequently placed on bedrest upon hospitaladmission and remain there, often without valid medicalreasons. The reasons for bedrest, as indicated in the chartreview, were not specified by any clinical staff and did notcorrelate with disease or treatment.
An important issue is whether a low mobility levelsimply served as a marker for severe illness; that is, moreseverely ill patients might have been less mobile, and thustheir poor outcomes should be attributed to their illnessrather than to their limited mobility. This issue was ad-dressed in several ways. First, it was demonstrated througha series of sequential models that multiple variables to con-trol for illness severity and comorbidity (APACHE II,Charlson index, and ICU/CCU stay)Feach of which had astrong independent effect on adverse outcomesFexertedonly modest confounding effects on the immobility varia-bles. Thus, despite multivariate adjustment, a low mobilitylevel retained its strong and significant effect on all adverseoutcomes. In addition, the effect of low mobility persistedwithin strata of all illness severity variables. Thus, using thebest available approaches to control for potential con-founding by illness severity, including controlling for mul-tiple risk adjustment systems (e.g., APACHE II, Charlsonindex, and ICU/CCU stay) through multivariate and strat-ification approaches, low and intermediate mobility madesignificant independent contributions to the adverse out-comes. Nevertheless, this issue cannot be definitively
Table 2. Bivariate Analysis of Mobility Level and Unadjusted Relative Risk (RR)
Outcome
Low Mobility Intermediate Mobility
Unadjusted RR (95% Confidence Interval)
Any decline in activities of daily living (n5 474)�w 4.1 (2.9–5.9) 2.5 (1.8–3.6)New institutionalization at discharge (n5 434) 5.6 (2.9–10.9) 3.5 (1.9–6.5)Death (n5 498) 29.0 (6.8–123.4) 10.0 (2.3–44.0)Death or new institutionalization (n5 498) 5.9 (3.8–9.4) 3.4 (2.1–5.4)
Note: RR is in comparison with the high mobility group.Low mobility is defined as average mobility score �4; intermediate mobility 44 and �8; high mobility 48.�Patients who were completely impaired at baseline were excluded from this analysis.w See Methods section for detailed definitions.
PREVALENCE AND OUTCOMES OF LOW MOBILITY 1267JAGS AUGUST 2004–VOL. 52, NO. 8
Table
3.IndependentContributionofLim
ited
Mobilityto
Adverse
Outcomes:EffectofAddingCovariables
Para
mete
r
FunctionalD
eclin
e�
New
Institu
tionaliz
ation�
Death�
Death
or
New
Institu
tionaliz
ation
Low
Mobili
tyIn
term
edia
teM
obili
tyLow
Mobili
tyIn
term
edia
teM
obili
tyLow
Mobili
tyIn
term
edia
teM
obili
tyLow
Mobili
tyIn
term
edia
teM
obili
ty
Odds
Ratio
(95%
Confidence
Inte
rval)wz
Unadju
ste
d9.3
(5.0
–17.1
)3.5
(2.2
–5.6
)7.7
(3.4
–17.4
)4.1
(2.1
–8.1
)40.3
(9.2
–177.8
)10.7
(2.4
–48.5
)10.9
(5.9
–20.2
)4.4
(2.5
–7.6
)A
dju
ste
dfo
rpre
adm
issio
nA
DLs
6.7
(3.5
–12.8
)3.1
(1.9
–5.0
)5.4
(2.3
–12.7
)3.4
(1.7
–6.9
)32.9
(7.1
–151.3
)10.0
(2.2
–45.4
)8.3
(4.3
–15.9
)4.0
(2.3
–7.0
)A
dju
ste
dfo
rA
DLs
and
dem
ogra
phic
s§
6.3
(3.3
–12.0
)2.8
(1.7
–4.6
)5.9
(2.4
–14.0
)3.0
(1.4
–6.1
)36.7
(7.9
–172.0
)11.0
(7.9
–172.0
)8.2
(4.2
–15.9
)3.6
(2.0
–6.4
)
Adju
ste
dfo
rA
DLs,
dem
ogra
phic
s,
and
AP
AC
HE
IIscore
6.4
(3.3
–12.4
)2.7
(1.6
–4.4
)6.3
(2.6
–15.4
)3.0
(1.4
–6.2
)34.4
(7.4
–170.1
)9.8
(2.1
–45.6
)8.0
(4.1
–15.8
)3.5
(2.0
–6.3
)
Adju
ste
dfo
rA
DLs,
dem
ogra
phic
s,
AP
AC
HE
IIscore
,and
Charlson
Com
orb
idity
Index
6.1
(3.1
–11.8
)2.5
(1.5
–4.2
)6.2
(2.6
–15.3
)2.9
(1.4
–6.1
)32.1
(6.6
–157.2
)8.7
(1.8
–41.5
)7.7
(3.9
–15.3
)3.4
(1.9
–6.0
)
Adju
ste
dfo
rA
DLs,
dem
ogra
phic
s,
AP
AC
HE
II,
Charlson
Com
orb
idity
Index,
and
inte
nsiv
ecare
unit/
coro
nary
care
unit
sta
y
5.6
(2.9
–11.0
)2.5
(1.5
–4.1
)6.0
(2.5
–14.8
)2.9
(1.4
–6.0
)34.3
(6.3
–185.9
)10.1
(1.9
–52.9
)7.2
(3.6
–14.4
)3.3
(1.8
–5.9
)
Note:Low
mobilityisdefined
asaveragemobilityscore
�4;interm
ediate
mobility44and
�8;highmobility48.
�See
Methodssectionfordetailed
definitions.
wOddsratioisin
comparisonwiththehighmobilitygroup.
z Po.006forallmodels.
§Dem
ographicsincluded
age,
sex,andmaritalstatus.
ADLs5
activitiesofdailyliving;APA
CHEII5
Acute
Physiology,AgeandChronic
HealthEvaluationII.
1268 BROWN ET AL. AUGUST 2004–VOL. 52, NO. 8 JAGS
answered without a randomized, controlled trial of immo-bility, which is probably not ethically feasible.
The effect of low mobility on adverse outcomes is clin-ically and biologically plausible. Low mobility and bedresthave been shown to be common during hospitalization.Adverse outcomes have been associated with hospitaliza-tion in older patients. This study demonstrates that lowmobility during hospitalization may be one pathway thatleads to the observed adverse outcomes. In addition, for thelowest mobility group, bedrest was frequently institutedwithout documented reasons, which may further exacer-bate the adverse effects of hospitalization. Patients andproviders often assume bedrest during hospitalization to bea therapeutic necessity, a concept that the results of thisstudy call into question.
Strengths of this study include the systematic assess-ment of mobility throughout hospitalization based on ob-servations of the primary nurses. Research personnel whowere blinded to the research questions collected these data.The availability of comprehensive patient-related data ondemographics, illness severity, comorbidity, and other var-iables allowed detailed adjustment for potential confound-ers.
Several important caveats deserve comment. First,since the data were collected, hospital lengths of stay havedecreased and standards of practice may have changed.Nevertheless, this should not affect the internal validity ofthe study nor the ability to address the study hypothesis,that is, that low mobility is associated with adverse out-comes. Moreover, the rigorous, clinically rich data collec-tion on a large hospitalized sample, using instruments andmethods that remain state of the art, should more than off-set the disadvantages of the age of the cohort. Second, al-though the primary nurses were prompted to account for allshifts during the previous 24 hours, theymay have tended torate the patient’s mobility based solely on their own obser-vations, with potential for underestimation of mobility.Nevertheless, one may argue that nurses may also have felt
responsible for maintaining mobility, thus introducing apotential bias towards overestimation of mobility levels.However, this effect was not demonstrated in the data. Al-though 24-hour observation or videotaping of patientswould have been ideal to determine patients mobility level,this was not feasible as part of this study. Therefore, nursingobservation remained the best available method to deter-mine mobility level.
The indications for bedrest were obtained via chartdocumentation, which may have missed some valid medicalreasons. However, any medical indication in the chart (byany member of the care team) was noted, and from a qual-ity-of-care standpoint, such an indication would have beenexpected. Moreover, interviewing hospital staff about theindications might have introduced substantial bias. Nurseinterviews occurred every other day, rather than daily, andsome episodes of low and high mobility may have beenmissed, but previous studies have demonstrated similarprevalence results to those presented.1
An important caveat is that mobility can vary accord-ing to institution and service type. This study was per-formed in a medicine service at a single hospital, and theprevalence of lowmobility may vary across service type andinstitution. However, it is unlikely that these variations inprevalence of lowmobility would affect the internal validityof the observations, that is, that low mobility is associatedwith adverse outcomes.
The mobility rating used in this study was created tocapture, in a general way, the range of mobility duringhospitalization and thus to test the hypothesis that greatermobility is important in supporting positive hospital out-comes. The rating is not intended for use as an instrument innonhospital settings. In addition, although use of a simplesummary measure was the best available method to quan-tify the mobility level and use all the observations available,this simple measure cannot fully capture all the informationabout mobility during hospitalization.
This study has shown low mobility to be an importantrisk factor for adverse hospital outcomes. Lowmobility andbedrest are common during hospitalization, and this studydocuments the serious adverse outcomes associated withthis practice. Given the important associated consequences,this study raises concerns about even the conventional wis-dom regarding ‘‘accepted’’ indications for bedrest. There isno standard of care for mobility in hospitalized older per-sons. A major impetus for this work was to lay the foun-dation for the necessity of developing such standards.Although beyond the scope of the present study, under-standing the reasons for low mobility through future in-vestigations will be crucial for intervening clinically orusing intervention studies. The goal of this paper is to in-crease awareness of the adverse outcomes associated withlow mobility and bedrest, which may be viewed asiatrogenic events leading to complications such as func-tional decline.
ACKNOWLEDGMENTS
The authors are indebted to the patients, families, andnurses at Yale–New Haven Hospital who participated inthe study.
Table 4. Documented Reasons for Bedrest in Low Mobil-ity Patients (N5176 Observations in 66 Patients)
Diagnosis or Procedure n (%)
No indication documented 102 (58.0)Imminently terminal condition 18 (10.2)Rule-out myocardial infarction 17 (9.7)Acute deep vein thrombosis 5 (2.8)Acute myocardial infarction 1 (0.6)Low back pain 1 (0.6)Lumbar puncture 1 (0.6)Vascular procedure 1 (0.6)Liver biopsy 1 (0.6)Other
Hypoxemia with exertion 8 (4.5)Acute postoperative period 6 (3.4)Hemorrhagic cerebrovascular accident 2 (1.1)Painful ischial skin breakdown 3 (1.7)Hypotension 3 (1.7)Pubic ramus fracture 2 (1.1)
Note: Data were missing for two patients/five observations.
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