Measuring frailty using claims data for pharmacoepidemiologic studies of mortality in older adults: evidence and recommendations

Purpose Geriatric frailty is a common syndrome of older adults that is characterized by increased vulnerability to adverse health outcomes and influences treatment choice. Pharmacoepidemiologic studies that rely on administrative claims data in older adults are limited by confounding due to unmeasured frailty. A claims-based frailty score may be useful to minimize confounding by frailty in such databases. We provide an overview of definitions and measurement of frailty, evaluated the claims-based models of frailty in literature, and recommend ways to improve frailty adjustment in claims analysis. Methods We searched MEDLINE and EMBASE from inception to April 2014, without language restriction, to identify claims-based multivariable models that predicted frailty or its related outcome, disability. We critically appraised their approach, including population, predictor selection, outcome definition, and model performance. Results Of 152 reports, three models were identified. One model that predicted poor functional status using healthcare service claims in a representative sample of community-dwelling and institutionalized older adults showed an excellent discrimination (C statistic, 0.92). The other two models that predicted disability using either diagnosis codes or prescription claims alone in institutionalized or frail adults had limited generalizability and modest model performance. None of the models have been applied to reduce confounding bias in pharmacoepidemiologic studies of drug therapy. Conclusions We found little research conducted on development and application of a claims-based frailty index for confounding adjustment in pharmacoepidemiologic studies in older adults. More research is needed to advance this innovative, potentially useful approach by incorporating the expertise from aging research. Copyright (c) 2014 John Wiley & Sons, Ltd.