Measuring Frailty in Medicare Data: Development and Validation of a Claims-Based Frailty Index

TLDR

Frailty is a key determinant of health status and outcomes of health‑care interventions in older adults, yet it is not readily measured in Medicare data. The study aimed to develop and validate a claims‑based frailty index (CFI) using Medicare Current Beneficiary Survey data from 2006 and 2011. The CFI was derived from 2006 claims to approximate a survey‑based frailty index, compared to the Charlson comorbidity index for predicting mortality, disability, falls, and health‑care utilization in 2007, and then validated by applying it to 2011 claims to predict the same outcomes in 2012, showing a 0.60 correlation with the survey index. In the development sample, the CFI matched the comorbidity index for mortality but outperformed it for disability, mobility impairment, falls, and skilled nursing facility days, and adding CFI to age, sex, and comorbidity improved prediction; in the validation sample, CFI and comorbidity performed similarly for mortality, confirming the CFI’s ability to quantify frailty‑related risk beyond demographics and traditional comorbidity measures.

Abstract

Frailty is a key determinant of health status and outcomes of health care interventions in older adults that is not readily measured in Medicare data. This study aimed to develop and validate a claims-based frailty index (CFI).We used data from Medicare Current Beneficiary Survey 2006 (development sample: n = 5,593) and 2011 (validation sample: n = 4,424). A CFI was developed using the 2006 claims data to approximate a survey-based frailty index (SFI) calculated from the 2006 survey data as a reference standard. We compared CFI to combined comorbidity index (CCI) in the ability to predict death, disability, recurrent falls, and health care utilization in 2007. As validation, we calculated a CFI using the 2011 claims data to predict these outcomes in 2012.The CFI was correlated with SFI (correlation coefficient: 0.60). In the development sample, CFI was similar to CCI in predicting mortality (C statistic: 0.77 vs. 0.78), but better than CCI for disability, mobility impairment, and recurrent falls (C statistic: 0.62-0.66 vs. 0.56-0.60). Although both indices similarly explained the variation in hospital days, CFI outperformed CCI in explaining the variation in skilled nursing facility days. Adding CFI to age, sex, and CCI improved prediction. In the validation sample, CFI and CCI performed similarly for mortality (C statistic: 0.71 vs. 0.72). Other results were comparable to those from the development sample.A novel frailty index can measure the risk for adverse health outcomes that is not otherwise quantified using demographic characteristics and traditional comorbidity measures in Medicare data.