Life-Space Assessment and Physical Activity Scale for the Elderly: validity of proxy informant responses.

OBJECTIVE

To validate the administration of the Life-Space Assessment (LSA) and Physical Activity Scale for the Elderly (PASE) surveys to proxy informants, as would be necessary when measuring long-term outcomes in acutely ill, hospitalized older adults who are initially incapacitated but eventually return to the community.

DESIGN

Cross-sectional study.

SETTING

General community.

PARTICIPANTS

Convenience sample of dyads (N=40) composed of an ambulatory older adult and a familiar companion.

INTERVENTIONS

Dyads completed the LSA and PASE surveys on 1 occasion. Companions based their responses on the recent mobility and physical activity of the older adult.

MAIN OUTCOME MEASURES

Paired total scores for each instrument.

RESULTS

At a group level, the difference between older adult and companion mean scores for each instrument was not significant (P>.05). Standardized mean difference values were small (d<0.1). Paired scores were significantly yet moderately associated: intraclass correlation coefficient(1,1)=.84 to .88; P<.01. Difference in scores was not associated with time spent together (P>.05) or older adult gait speed (P>.05). At an individual level, older adults and companions agreed more closely on the LSA than on the PASE. However, disagreement in excess of estimated measurement error occurred in 40% of the dyads for the LSA and in none of the dyads for the PASE.

CONCLUSIONS

Older adults and companions collectively provided similar responses on each instrument. Nonetheless, varying levels of agreement within individual dyads suggested that proxy responses should be considered carefully. Implications for clinical research and practice research are discussed.