Measuring physical function in community-dwelling older persons: a comparison of self-administered, interviewer-administered, and performance-based measures.
OBJECTIVE
To compare two self-administered, one interviewer-administered, and one performance-based measure of physical function in community-based older persons.


METHODS
Eighty-three subjects were recruited from meal sites, senior recreation centers, and senior housing units for a comprehensive geriatric assessment program. At the time of screening, study participants self-administered the Functional Status Questionnaire (FSQ) and were administered the Katz Activities of Daily Living (ADL) and the Older Americans Resources and Services Instrumental Activities of Daily Living (OARS-IADL) instruments by interview. Participants also completed the Physical Performance Test (PPT) and were given the Medical Outcomes Study SF-36 to self-administer on site or at home and return by mail.


RESULTS
All 83 subjects completed FSQ, Katz ADL, OARS-IADL, and PPT; 72 returned SF-36 forms. Correlations between the two self-administered physical function measures (FSQ and SF-36) were higher than between self-administered and interviewer-assessed (ADL and OARS-IADL) or performance-based (PPT) measures. When assessed for construct validity, the self-administered, OARS, and PPT measures had comparable correlations with role limitations as a result of physical health problems, but relationships between physical functional status measures and other SF-36 measures of health were inconsistent.


CONCLUSIONS
The relationships between commonly used self-administered, interviewer-administered, and performance-based measures of physical function were inconsistent and weak, suggesting that these instruments are not measuring the same construct.
Reuben
D B
DB
Multicampus Program in Geriatric Medicine and Gerontology, UCLA School of Medicine 90024-1687.
Valle
L A
LA
Hays
R D
RD
Siu
A L
AL
D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D003256:Community Participation; D015987:Effect Modifier, Epidemiologic; D005260:Female; D015577:Geriatric Assessment; D006304:Health Status; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D008875:Middle Aged; D010808:Physical Examination / Q000379:methods*; D010809:Physical Fitness; D011788:Quality of Life; D011897:Random Allocation; D015203:Reproducibility of Results; D012650:Self Disclosure; D011795:Surveys and Questionnaires