Collective Weakness and Fluidity in Weakness Status Associated With Basic Self-Care Limitations in Older Americans

To examine the associations of 1) absolute and normalized weakness cut-points, 2) collective weakness categories, and 3) changes in weakness status on future activities of daily living (ADL) limitations in older Americans.

The analytic sample included 11,656 participants aged ≥65-years from the 2006-2018 waves of the Health and Retirement Study. ADL were self-reported. A handgrip dynamometer measured handgrip strength (HGS). Males were classified as weak if their HGS was <35.5-kg (absolute), <0.45-kg/kg (body mass normalized), or <1.05-kg/kg/m² (body mass index (BMI) normalized); females were considered weak if their HGS was <20.0-kg, <0.337-kg/kg, or <0.79-kg/kg/m². Collective weakness categorized those below 1, 2, or all 3 absolute and normalized cut-points. These collective categories were also used to classify observed changes in weakness status over time (onset, persistent, progressive, recovery).

Older Americans below absolute and normalized weakness cut-points had greater future ADL limitations odds: 1.34 (95% confidence interval (CI): 1.22-1.47) for absolute, 1.36 (CI: 1.24-1.50) for BMI normalized, and 1.56 (CI: 1.41-1.73) for body mass normalized. Persons below 1, 2, or 3 cut-points had 1.36 (CI: 1.19-1.55), 1.60 (CI: 1.41-1.80), and 1.70 (CI: 1.50-1.92) greater odds for future ADL limitations, respectively. Those in each changing weakness classification had greater future ADL limitation odds: 1.28 (CI: 1.01-1.62) for onset, 1.53 (CI: 1.22-1.92) for persistent, 1.72 (CI: 1.36-2.19) for progressive, and 1.34 (CI: 1.08-1.66) for recovery.

The presence of weakness, regardless of cut-point and change in status over time, was associated with greater odds for future ADL limitations.