Predicting the risk of mobility difficulty in older women with screening nomograms - The women's health and aging study II

Background: A major obstacle to screening for early mobility disability tie , mobility difficulty), a major public health concern, is the lack of a met hod that identifies those who are at high risk. The goal of this study was to develop easy-to-use clinical nomograms or estimation of the probability of incident mobility difficulty. Methods: We conducted a population-based prospective study using data from 266 high physically and cognitively functioning older women, aged 70 to 80 years, who were free of mobility disability at the baseline evaluation of t he Women's Health and Aging Study II. The outcome measure was incident mobi lity disability within 18 months, defined as self-reported difficulty walki ng 0.8 km, climbing 10 steps, or transferring from or into a car or bus. Lo gistic regression and receiver operating characteristic curve analyses were used for evaluation of the optimal combination of self-reported and perfor mance-based mobility measures. Bootstrap sampling and estimation was used f or validation. Results: Predictive nomograms were developed based on a final model that in cluded 3 simple-to-obtain measures of preclinical disability: self-report o f modification in mobility tasks without having difficulty with them, one-l eg stance balance, and time to walk 1 m at a usual pace. Final model accura cy (as estimated by the area under the receiver operating characteristic cu rve) was 73% (SE=0.04). Validation analysis confirmed the high accuracy of these nomograms. Conclusions: An original tool was developed for assessment of the risk of m obility difficulty in older women that can be used to assist physicians and researchers in deciding which women to target for preventive interventions .