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

Abstract

Aims: 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. Methods: The analytic sample included 11,656 participants aged ≥65 years from the 2006-2018 waves of the RAND Health and Retirement Study. ADL were self-reported. A handgrip dynamometer was used to measure 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. Participants were similarly categorized as being 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). Results: 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. Conclusions: The presence of weakness, regardless of cut-point and change in status over time, was associated with greater odds for future ADL limitations.

Keywords

• Aging
• Geriatric assessment
• Longevity
• Muscle strength
• Muscle strength dynamometer