Development and validation of a prediction model for self-reported mobility decline in community-dwelling older adults

Objectives The aim of this study is to develop and validate two models to predict 2-year risk of self-reported mobility decline among community-dwelling older adults. Study Design and Setting We used data from a prospective cohort study of people aged 65 years and over in England. Mobility status was assessed using the EQ-5D-5L mobility question. The models were based on the outcome: Model 1, any mobility decline at 2 years; Model 2, new onset of persistent mobility problems over 2 years. Least absolute shrinkage and selection operator logistic regression was used to select predictors. Model performance was assessed using C-statistics, calibration plot, Brier scores, and decision curve analyses. Models were internally validated using bootstrapping. Results Over 18% of participants who could walk reported mobility decline at year 2 (Model 1), and 7.1% with no mobility problems at baseline, reported new onset of mobility problems after 2 years (Model 2). Thirteen and 6 out of 31 variables were selected as predictors in Models 1 and 2, respectively. Models 1 and 2 had a C-statistic of 0.740 and 0.765 (optimism < 0.013), and Brier score = 0.136 and 0.069, respectively. Conclusion Two prediction models for mobility decline were developed and internally validated. They are based on self-reported variables and could serve as simple assessments in primary care after external validation.