Frailty and Disability in Older Adults with Intellectual Disabilities: Results from the Healthy Ageing and Intellectual Disability Study

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  • Frailty and Disability in Older Adults with IntellectualDisabilities: Results from the Healthy Ageing and IntellectualDisability Study

    Heleen M. Evenhuis, PhD,* Heidi Hermans, MSc,* Thessa I. M. Hilgenkamp, MSc,*

    Luc P. Bastiaanse, MSc,* and Michael A. Echteld, PhD*

    OBJECTIVES: To obtain first insight into prevalence andcorrelates of frailty in older people with intellectual dis-ability (ID).

    DESIGN: Population-based cross-sectional study in per-sons using formal ID services.

    SETTING: Three Dutch care provider services.

    PARTICIPANTS: Eight hundred forty-eight individualswith borderline to profound ID aged 50 and older partici-pating in the Healthy Ageing and Intellectual Disability(HA-ID) Study.

    MEASUREMENTS: All participants underwent an exten-sive health examination. Frailty was diagnosed accordingto Cardiovascular Health Study criteria. Associationsbetween frailty and participant characteristics were investi-gated using multivariate logistic regression analysis.

    RESULTS: Prevalence of frailty was 11% at age 50 to 64and 18% at age 65 and older. Age, Down syndrome,dementia, motor disability, and severe ID were signifi-cantly associated with frailty, but only motor disabilityhad a unique association with frailty. In a regressionmodel with these variables, 25% of the variance of frailtywas explained.

    CONCLUSION: At age 50 to 64, prevalence of frailty isas high as in the general population aged 65 and older (79%), with a further increase after the age of 65. Motordisability only partially explains frailty. Future studiesshould address health outcomes, causes, and preventionof frailty in this population. J Am Geriatr Soc 60:934938, 2012.

    Key words: intellectual disability; frailty; prevalence

    As a result of normalizing life expectancy in the popula-tion with intellectual disabilities (IDs),1 the numberof older persons with IDs is rapidly increasing. A majorityof these persons now live in the community and make useof regular health care. Apart from people with Downsyndrome, with early sensory losses and dementia,2,3 thereare no signs that primary aging is premature in this group.Nevertheless, professionals working for this population,have generally accepted the idea of early aging for severaldecades, primarily based on limited life expectancy andearly deterioration of activities of daily living.4,5 Evidence-based insight into conditions underlying this supposedearly aging may contribute to health policies aimed atprevention, timely detection, and intervention in thispopulation or specific subgroups. Tentative prevalencedata regarding frailty in this population were published in2010, based on a questionnaire assessment based on twodistinct approaches of frailty, which hampers comparisonwith studies in the general population.6

    Recognizing that validity of internationally establishedfrailty criteria might be different in a population withlifelong disability, as a first step, a cross-sectionalinventory of frailty, diagnosed according to CardiovascularHealth Study (CHS) criteria,7 was performed in a popula-tion that was nearly representative of older clients ofDutch ID care provider services. It was hypothesized that,in this group, frailty would be present at a younger agethan in the general older population and that frailty wouldoverlap with but not be identical to disability. Therefore,frailty prevalence and its associations with age, sex, Downsyndrome, dementia, care setting, motor disability, andsevere ID were studied.

    From the *Department of General Practice, Intellectual DisabilityMedicine, Erasmus University Medical Centre, Rotterdam, theNetherlands; Amarant Center for Intellectual Disability, Tilburg, theNetherlands; Abrona Center for Intellectual Disability, Huis ter Heide,the Netherlands; and Ipse de Bruggen Center for Intellectual Disability,Zwammerdam, the Netherlands.

    Address correspondence to Prof. Heleen M. Evenhuis, Department ofGeneral Practice, Erasmus University Medical Center, IntellectualDisability Medicine, PO Box 2040, 3000 CA Rotterdam, the Netherlands.E-mail:

    DOI: 10.1111/j.1532-5415.2012.03925.x

    JAGS 60:934938, 2012

    2012, Copyright the AuthorsJournal compilation 2012, The American Geriatrics Society 0002-8614/12/$15.00


    Study Design and Participants

    This study was part of a large cross-sectional study:Healthy Ageing and Intellectual Disability (HA-ID). Thestudy population consists of clients aged 50 and older in aconsortium of three care provider services in the Nether-lands offering specialized support varying from ambulatorysupport or day care for clients living independently or withfamily to residential settings providing support of indepen-dency or more or less intensive care. In most high-incomecountries, regional formal ID services serve comparablegroups as in the Netherlands, meaning that the largergroup of people with borderline or mild IDs not using anyspecialized services or living in general geriatric settingshas not been included.

    Informed consent was obtained from 1,069 clientsaged 50 and older or their legal representatives; 1,050 par-ticipated in the assessments. The study population is nearlyrepresentative of the consorts total client population aged50 and older, with a slight underrepresentation of men,individuals living independently, and individuals aged 80and older. Details regarding design, recruitment, and rep-resentativeness of the sample and diagnostic methods havebeen published previously.8 The Medical Ethics Committeeof the Erasmus Medical Center Rotterdam (MEC 2008234) and the ethics committees of the participating careprovider services provided ethics approval. The studyadheres to the Declaration of Helsinki for research involv-ing human subjects.

    Diagnostic Measurements

    All participants underwent an extensive diagnostic assess-ment, consisting of a physical assessment, a fitness test bat-tery, measurement of physical activity using pedometersfor 2 weeks, standardized mealtime observations of swal-lowing, and standardized psychiatric assessment of depres-sion and anxiety.8

    Diagnoses of Down syndrome, confirmed by karyotyp-ing, were retrieved from participant files. Dementia wasdefined as possible or probable dementia. Diagnoses wereobtained from participants physicians and behavioral spe-cialists and were included in the analysis only in the caseof consensus between these professionals. Care setting wasclassified as centralized setting (primarily care), commu-nity-based group home (primarily support), or ambulatorysupport (living independently or with family, participatingin daycare or getting specific support).

    Mobility was judged before the fitness assessment andclassified as independent mobility, mobility with aids, andmobility in wheelchair. Motor disability was defined asmobility with aids or wheelchair. Information was notavailable on age of onset of motor disability.

    Psychologists or behavioral scientists had performedintelligence quotient (IQ) testing after admission to thecare organizations; severity of ID had been classified asborderline (IQ 7080), mild (IQ 5569), moderate (IQ 3554), severe (IQ 2534), or profound (IQ < 25). This infor-mation was retrieved from the files. For the analysis,severe and profound ID were combined as severe ID.

    Frailty and Disability

    According to the CHS criteria, participants with at leastthree of the following five criteria were defined as frail:weight loss, poor grip strength, slow walking speed, lowphysical activity, and poor endurance or exhaustion. Par-ticipants with one or two criteria were considered prefrailand participants with no criteria as robust.7 The criteriawere operationalized as follows.

    Weight loss: an item of the Mini Nutritional Assessment,9

    weight loss during the past 3 months was assessed on a4-point rating scale. Losses >3 kg were scored.

    Grip strength was measured using a Jamar Hand Dyna-mometer (#5030J1, Sammons Preston Rolyan, Dolge-ville, NY) as part of the fitness assessment. Poor gripstrength was defined according to CHS criteria, withstratification according to sex and body mass index.7

    Comfortable walking speed was tested as part of the fit-ness assessment and was measured as the average ofthree recordings of the time to complete a distance of5 m. Slow walking speed was defined according to CHScriteria, with stratification according to sex and height.7

    All participants in a wheelchair and all participants whocould not participate in the walking speed assessmentbecause of physical limitations were scored as having aslow walking speed.

    Physical activity was tested using pedometers (NL-1000;New Lifestyles, Lees Summit, MO) for 14 days. Theminimal comfortable walking speed required for a reli-able measurement was 3.2 km/hour. All participantswalking fewer than 5,000 steps/day (sedentary life-style)10 were scored positive on low physical activity, aswere all participants in a wheelchair and all participantswho could not engage in the walking speed assessmentbecause of physical limitations.

    Poor endurance or exhaustion was assessed using theitem Lacks energy of the Anxiety, Depression andMood Scale.11 This item has a 4-point rating scale. Theno problem and mild problem answers were recordedinto no and the moderate problem and severe problemanswers into yes.


    Because not all participants were able to participate in allassessments,8 frailty criteria could be missing. All partici-pants with at least three criteria measured were includedin the analyses. Characteristics of included and excludedparticipants were compared using chi-square (v2) statistics.

    Prevalences of frailty and prefrailty and 95% confi-dence intervals were calculated for the total includedgroup and for subgroups according to age, sex, care set-ting, Down syndrome, dementia, severity of ID, and motordisability. Prevalences of frailty and prefrailty in subgroupswere compared using chi-square statistics.

    A multivariate logistic regression analysis was per-formed to determine whether Down syndrome, dementia,motor disability, and severe ID are independently associ-ated with frailty, controlling for the effect of age (5064vs 65) and gender. Age and sex were entered into theequation first, after which Down syndrome, dementia,


  • motor disability, and severe ID were entered simulta-neously. Correlations of frailty and motor disability withage were tested using Spearman correlation coefficients.


    Eight hundred forty-eight of the 1,050 participants hadthree or more criteria assessed and were included in theanalyses. The excluded subgroup (n = 202) had a sex andage distribution similar to that of this group (data notshown) but included significantly more persons with severeID (v2 = 51.6, P = .01) and motor disability (v2 = 22.5,P = .01). In the included group, cause of ID was unknownin 673, Down syndrome in 120, other genetic syndromesin 13, and varying other diagnoses in 42 participants.Cerebral palsy was not scored as a causal diagnosis of ID.

    The distribution of age, sex, care setting, Down syn-drome, dementia, severity of ID, and motor disabilityis presented in the second column of Table 1. Of 120participants with Down syndrome, 47 had a diagnosis ofdementia.

    Of the total included population, 27% was robust(95% confidence interval (CI) = 2430), 60% prefrail(95% CI = 5763), and 13% frail (95% CI = 1115).Prevalence of frailty was 11% (95% CI = 814%) in the

    group aged 50 to 64, 18% (95% CI = 1323) in the groupaged 65 and older, and 21% (95% CI = 1232) in thegroup aged 70 and older.

    Thirty-seven of 833 participants (4%) lost weight, and373 of 701 (53%) had poor grip strength, 138 of 827(17%) exhaustion, 263 of 795 (33%) slow walking speed,and 254 of 421 (60%) low physical activity. Because ofmissing data, total numbers were never 848. Physicalactivity could not be established in a majority of partici-pants, largely because of unreliable pedometer results dueto a walking speed slower than 3.2 km/hour (n = 256 inthe total HA-ID study population) and limited understand-ing or noncooperation (n = 204).12

    Prevalences of frailty and prefrailty in subgroups andrelationships with other participant characteristics are pre-sented in Table 1, showing significant associations with allcharacteristics except sex. Down syndrome was associatedonly with prefrailty. Multivariate logistic regression analy-sis confirmed that, if age and sex were entered into theequation, age was positively associated with frailty, withparticipants aged 65 and older being 1.7 times as likely tobe frail as the younger group. After entering Down syn-drome, dementia, motor disability, and severity of ID intothe equation, motor disability was independently and verystrongly associated with frailty; people using walking aids

    Table 1. Participant Characteristics (N = 848) and Distribution of Frailty


    Total Robust Prefrail Frail

    Difference (Pre)Frailty, Chi-Squaren (%)

    Total 848 230 (27) 508 (60) 110 (13)Age

    5064 582 (69) 178 (31) 341 (59) 63 (11) 15.33c

    65 266 (31) 52 (20) 167 (63)d 47 (18)d5069 777 (82) 221 (28) 461 (59) 95 (12) 10.45b

    70 71 (18) 9 (13) 47 (66)d 15 (21)dSex

    Female 412 (49) 108 (26) 251 (61) 53 (13) 0.39Male 436 (51) 122 (28) 257 (59) 57 (13)

    Care settingCentralized 436 (51) 86 (20) 270 (62)d 80 (18)d 48.56c

    Community 363 (43) 118 (33) 215 (59) 30 (8)Ambulatory support 41 (5) 23 (56) 18 (44) 0

    Causes of IDDown syndrome 120 (14) 19 (16) 84 (70)d 17 (14) 7.25a

    Other 621 170 (27) 367 (59) 84 (14)Dementia

    Yes 74 9 (12) 49 (66)d 16 (22)d 10.09b

    No 659 179 (27) 396 (60) 84 (13)Severity of ID

    Borderline to mild 218 (26) 91 (42) 113 (52) 14 (6) 37.95c

    Moderate 425 (50) 101 (24) 263 (62)d 61 (14)d

    Severe to profound 185 (22) 35 (19) 116 (63)d 34 (18)d

    Motor disabilityNo 613 (72) 216 (35) 365 (59.5) 32 (5) 207.39c

    Walking aid 121 (14) 10 (8) 86 (71)d 25 (21)d

    Wheelchair 107 (13) 0 54 (50.5)d 53 (49.5)d

    a P < .05.b P < .01.c P < .001.d Subgroup with significantly more (pre)frailty.

    Frail, 3/5 Cardiovascular Health Study criteria; prefrail, 12/5 criteria; robust, 0/5 criteria.ID = intellectual disability.

    936 EVENHUIS ET AL. MAY 2012VOL. 60, NO. 5 JAGS

  • or a wheelchair were 9.8 times as likely to be frail as thosewho walked independently.

    The proportion of explained variance was 0.25 (Nagel-kerke R2), and the overall model fit the data adequately,as indicated by the Hosmer and Lemeshow test (v2 = 8.98;P = .34). The correlation of frailty and motor disabilitywith age is shown in Figure 1.


    This is the first large-scale study of frailty in a populationthat was nearly representative of Dutch people with IDreceiving formal care aged 50 and older applying CHS cri-teria for frailty. Persons with all levels of ID and supportneeds were included and comprehensively tested usinginternationally accepted diagnostic methods. Thirteen per-cent of the ID population is frail and 60% prefrail,whereas 28% to 31% of those aged 50 to 69 were labelledrobust, declining to...