Associations of the step-up test and lower limb dysfunction: A post-hoc analysis of a prospective cohort study.

Abstract

Step-up ability is considered to be associated with lower limb dysfunction. The objective of this research was to assess the height of the tallest step that could be mounted and to investigate its association with lower limb dysfunction. We previously conducted a two-year follow-up prospective cohort study. The study subjects were 119 patients receiving physiotherapy or exercise therapy at an orthopedic surgery clinic. The items evaluated were step-up ability (maximum step height), the timed up and go test, one-leg standing time and the 5-question Geriatric Locomotive Function Scale. The primary endpoint was the prevalence of locomotive syndrome, whereas secondary endpoint was musculoskeletal ambulation disability symptom complex (MADS). Evaluations were carried out at the time of the initial assessment and two years later. We used a multiple logistic regression model with age, sex, height, weight and each functional test as exploratory variables. R2 and C-statistics were calculated and these "optimism" biases were corrected using a bootstrap technique. Maximum step height was strongly correlated with the prevalence of locomotive syndrome [odd ratio (95% confidence intervals), 0.52 (0.32, 0.87), p=0.0074] and was correlated with MADS [0.45 (0.22, 0.92), p=0.0138]. Additionally, maximum step height was also strongly correlated with post follow-up locomotive syndrome [0.39 (0.18, 0.84), p=0.0010]. The results suggest that step-up ability may represent a simple and useful tool which is associated with lower limb dysfunction.