Introduction To assess the ability of neuromuscular functions to predict the occurrence of disability in Japanese general population.

Methods The large-scale population-based cohort study entitled research on osteoarthritis/osteoporosis against disability (ROAD) has established three cohorts, from an urban, a mountainous, and a coastal area. The first follow-up survey was performed after 3 years and was attended by 2479 of 3040 baseline participants (81.5%). From the entire ROAD data, we utilised the data of the elderly participants (≥65 years) from the mountainous and coastal cohorts. Disability was defined by a relevant certification committee comprising clinical experts and physicians from each municipality. To evaluate the predictive ability of the indices of neuromuscular function, logistic regression analysis was conducted using occurrence of disability as an objective factor and the grip strength and walking speed for 6 m as explanatory factors after adjustment for age, gender, and body mass index.

Results Of the 914 participants who completed both baseline and first follow-up surveys, 88 individuals (9.6%) were defined as new cases of disability over 3 years. Logistic regression analysis indicated that the higher the grip strength, the lower is the risk of disability (+1 kg; OR, 0.90; 95% CI 0.86 to 0.95), whereas the lesser the walking speed, the greater is the risk (+1 s; OR, 1.15; CI 1.07 to 1.23).

Conclusions The cumulative incidence of disability among the elderly was 9.6% over 3 years. The indices of neuromuscular function may be potential predictive factors of the occurrence of disability over 3 years.