Objective: we aimed to evaluate the Foundation for the National Institutes of Health (FNIH) criteria for weakness and low muscle mass and the Study of Osteoporotic Fractures (SOF) frailty index for prediction of long-term, all-cause mortality.

Design: community-based cohort study.

Setting: semi-rural community of Merelbeke (Belgium).

Subjects: ambulatory men aged 74 and more (n = 191).

Methods: weakness was defined on previously established criteria as low grip strength (<26 kg) or low grip strength-to-body mass index (BMI) ratio (<1.00). Low muscle mass (dual-energy x-ray absorptiometry) was categorised as low appendicular lean mass (ALM; predefined <19.75 kg) or low ALM-to-BMI ratio (predefined <0.789). Frailty status was assessed using the components of weight loss, inability to rise from a chair and poor energy (SOF index). Survival time was calculated as the number of months from assessment in 2000 until death or up to 15 years of follow-up.

Results: mean age of the participants was 78.4 ± 3.5 years. Combined weakness and low muscle mass was present in 3-8% of men, depending on the criteria applied. Pre-frailty and frailty were present in 30 and 7% of men, respectively. After 15 years of follow-up, 165 men (86%) died. Both the presence of combined weakness and low ALM-to-BMI ratio (age-adjusted HR = 2.50, 95% CI = 1.30-4.79) and the presence of SOF frailty (age-adjusted HR = 2.64, 95% CI = 1.44-4.86) were associated with mortality.

Conclusions: our findings confirm the predictive value for mortality of the non-distribution-based FNIH criteria and SOF index in older community-dwelling Belgian men.