Chronic Conditions and Mortality in Medicare Beneficiaries Before and After the COVID-19 Pandemic

Did the prevalence of comorbidities in Medicare beneficiaries, as assessed by claims-based algorithms, change post–COVID-19, and are there implications for risk adjustment?In this cross-sectional study of 59 514 042 beneficiaries in 2019 and 63 202 599 beneficiaries in 2022, the mean total number of comorbidities coded per beneficiary from 2019 to 2022 had a 0.23 decrease in fee-for-service Medicare and a 0.15 decrease in Medicare Advantage. In multivariable analyses, 11 comorbidities (36.7%) had a stronger positive association with mortality and 4 comorbidities (13.3%) had stronger negative association with mortality in Q1 2022 than in Q1 2019.These findings suggest that analyses that included both pre– and post–COVID-19 data and used claims-based risk adjustment may be subject to bias.

Corresponding Author: R.J. Waken, PhD, Washington University in St Louis School of Medicine660 S Euclid Ave, St Louis MO 63110 (rjwaken@wustl.edu).

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