Factors associated with falls in Japanese polio survivors

Purpose:To identify factors associated with falls in Japanese polio survivors and assess the extent of their impact. Materials and methods:Subjects were 128 polio survivors. Fall history and fear of falling, lower limb muscle strength, gait ability (determined by walking speed and number of steps per day), post-polio syndrome incidence, and orthosis or walking aid use were assessed, and factors associated with falls were identified using logistic regression analysis. Results:The fall rate was 64%. Fallers (subjects with one or more falls in the preceding 12 months) had low lower limb muscle strength, slow walking speed, high total scores on the Fall Efficacy Scale-International, which assesses fear of falling, and a high orthosis use rate. Knee extension muscle strength on the weaker side was identified as a main factor influencing risk of falls (odds ratio: 0.72, 95% confidence interval: 0.56-0.96). Receiver operating characteristic curve analysis gave a cutoff value for knee extension muscle strength on the weaker side of 0.42 N/kg or lower. Conclusion:Low knee extension muscle strength on the weaker side was associated with falls, but predictive ability using a single internal factor might be poor. It appears that a comprehensive examination, including other factors, is required.