Discrimination ability of comorbidity, frailty, and subjective health to predict mortality in community-dwelling older people: Population based prospective cohort study

Abstract

ObjectiveTo investigate the added value of comorbidity, frailty, and subjective health to mortality predictions in community-dwelling older people and whether it changes with increasing age. Participants36,751 community-dwelling subjects aged 50–100 from the longitudinal Survey of Health, Ageing, and Retirement in Europe. MethodsMortality risk associated with Comorbidity Index, Frailty Index, Frailty Phenotype, and subjective health was analysed using Cox regression. The extent to which health indicators modified individual mortality risk predictions was examined and the added ability to discriminate mortality risks was assessed. Main outcome measuresThree-year mortality risks, hazard ratios, change in individual mortality risks, three-year area under the receiver operating characteristic curve (AUC). ResultsThree-year mortality risks increased 41-folds within an age span of 50years. Hazard ratios per change in health indicator became less significant with increasing age (p-value<0·001). AUC for three-year mortality prediction based on age and sex was 76·9% (95% CI 75·5% to 78·3%). Information on health indicators modified individual three-year mortality risk predictions up to 30%, both upwards and downwards, each adding <2% discriminative power. The added discrimination ability of all health indicators gradually declined from an extra 4% at age 50–59 to <1% in the oldest old. Trends were similar for one-year mortality and not different between sexes, levels of education, and household income. ConclusionCalendar age encompasses most of the discrimination ability to predict mortality. The added value of comorbidity, frailty, and subjective health to mortality predictions decreases with increasing age.