Costs Associated With Progression of Mildly Reduced Kidney Function Among Medicare Advantage Enrollees.
RATIONALE & OBJECTIVE: The prevalence of early chronic kidney disease (CKD) in older adults has increased in the past 2 decades, yet CKD disease progression, overall, is variable. It is unclear whether health care costs differ by progression trajectory. The purpose of this study was to estimate the trajectories of CKD progression and examine Medicare Advantage (MA) health care costs of each trajectory over a 3-year period in a large cohort of MA enrollees with mildly reduced kidney function. STUDY DESIGN: Cohort study. SETTING & POPULATION: 421,187 MA enrollees with stage G2 CKD in 2014-2017. OUTCOMES: We identified 5 trajectories of kidney function over time. MODEL PERSPECTIVE & TIMEFRAME: Mean total health care costs for each of the trajectories were described in each of the following 3 years from a payer perspective: 1 year before and 2 years after the index date establishing stage G2 CKD (study entry). RESULTS: The mean estimated glomerular filtration rate (eGFR) at study entry was 75.9 mL/min/1.73 m2 and the median (interquartile range) follow-up period was 2.6 (1.6, 3.7) years. The cohort had a mean age of 72.6 years and had predominantly female participants (57.2%), and White (71.2%). We identified the following 5 distinct trajectories of kidney function: a stable eGFR (22.3%); slow eGFR decline with a mean eGFR at study entry of 78.6 (30.2%); slow eGFR decline with an eGFR at study entry of 70.9 (28.4%); steep eGFR decline (16.3%); and accelerated eGFR decline (2.8%). Mean costs of enrollees with accelerated eGFR decline were double the MA enrollees' mean costs in each of the other 4 trajectories in every year ($27,738 vs $13,498 for a stable eGFR 1 year after study entry). LIMITATIONS: Results may not generalized beyond MA and a lack of albumin values. CONCLUSIONS: The small fraction of MA enrollees with accelerated eGFR decline has disproportionately higher costs than other enrollees with mildly reduced kidney function.