Assessing risk for the onset of functional dependence among older adults: the role of physical performance.

BACKGROUND: Approximately 10% of nondisabled, community-dwelling adults aged 75 years and older lose independence in basic activities of daily living (ADLs) each year. The purpose of this study was to evaluate whether simple tests of physical performance could identify older adults, independent in their basic ADLs, who were at increased risk for the onset of functional dependence.

METHODS: Among a representative cohort of 1103 community-dwelling adults aged 72 years and older, we evaluated the 664 subjects who were cognitively intact and independent in their basic ADLs at the baseline interview. All cohort members had undergone a comprehensive assessment, including a battery of qualitative and timed performance tests. The main outcome event was the onset of functional dependence, defined as a new disability in one or more of the seven basic ADLs at the 1-year follow-up.

RESULTS: Functional dependence developed in 53 (9%) of the 563 subjects who had complete data at the 1-year follow-up. Eight of the 12 qualitative tests and all six of the timed tests were significantly associated (P < .05) with the onset of functional dependence. Both qualitative and timed performance tests demarcated subjects into groups at low and high risk for functional dependence. Four timed tests--chair stands, rapid gait, 360 degrees turn, and bending over--showed a threshold phenomenon, where the rate of new dependence increased slowly with worsening performance until a critical point (or threshold) was reached, and the rate of dependence increased substantially. For timed chair stands, for example, the rates of functional dependence within quarters of worsening performance were 5.3%, 6.3%, 6.7%, and 16%. The risk of functional dependence was markedly elevated (30%-50%) for subjects who were unable to perform the timed tests.

CONCLUSIONS: Several simple tests of physical performance were strongly associated with the onset of functional dependence. These results support the potential use of physical performance tests to develop a risk assessment strategy that could identify subgroups of older persons, independent in all ADLs, who are at increased risk for functional dependence.