Weakness May Have a Causal Association With Early Mortality in Older Americans: A Matched Cohort Analysis

Objectives: Quantifying the association between muscle weakness and mortality with carefully matched cohorts will help to better establish the impact of weakness on premature death. We used a matched cohort analysis in a national sample of older Americans to determine if those who were weak had a higher risk for mortality compared with control groups with incrementally higher strength capacities.

Design: Longitudinal panel.

Setting: Detailed interviews that included physical measures were conducted in person, whereas core interviews were often performed over the telephone.

Participants: Data from 19,729 Americans aged at least 50 years from the 2006-2014 waves of the Health and Retirement Study were analyzed.

Measures: A handgrip dynamometer was used to assess handgrip strength (HGS) in each participant. Men with HGS <26 kg were considered weak, ≥26 kg were considered not weak, and ≥32 kg were considered strong. Women with HGS <16 kg were classified as weak, ≥16 kg were classified as not-weak, and ≥20 kg were classified as strong. The National Death Index and postmortem interviews determined the date of death. The greedy matching algorithm was used to match cohorts.

Results: Of the 1077 weak and not-weak matched pairs, 401 weak (37.2%) and 296 not-weak (27.4%) older Americans died over an average 4.4 ± 2.5-year follow-up. There were 392 weak (37.0%) and 243 strong (22.9%) persons who died over a mean 4.5 ± 2.5-year follow-up from the 1057 weak and strong matched pairs. Those in the weak cohort had a 1.40 [95% confidence interval (CI) 1.19, 1.64] and 1.54 (CI 1.30, 1.83) higher hazard for mortality relative to persons in the not-weak and strong control cohorts, respectively.

Conclusions and implications: Our findings may indicate a causal association between muscle weakness and mortality in older Americans. Health care providers should include measures of HGS as part of routine health assessments and discuss the health risks of muscle weakness with their patients.