Background: Age-related decline in muscle strength is among of the most important factors in the aging process leading to disability. This study examines age-related changes in handgrip strength through a 22-year follow-up in men and women. Because handgrip strength is associated with mortality, this study also accounts for the selection effect of right censoring by comparing the estimates of handgrip strength decline based either on only the handgrip strength data or on the data of both the handgrip strength and survival times.
Methods: Data are from 1,890 men and women aged 30 years or more at baseline participating in the population-based Mini-Finland Health Examination Survey (1978-1980) with repeated handgrip strength measurement in 2000-2001.
Results: In men aged 31-41 years, the annual decrease in handgrip strength was approximately 3.5 Newtons (N). After that, the decrease accelerated and stabilized around the age of 75 years, being approximately 7.3 N per year. In women, respectively, prior to 45 years, the annual decrease was approximately 2 N and after age 80 years approximately 4 N per year. The estimates for the handgrip strength decline were more pronounced when the right censoring due to death was accounted for, especially for persons aged 65 years and older.
Conclusions: Our work confirms that the right censoring, which depends on the outcome of interest, should be accounted for in analyses.