Prevalence of Renal Impairment in a US Commercially Insured Rheumatoid Arthritis Population: A Retrospective Analysis.

Introduction: Global prevalence estimates for chronic kidney disease (CKD) in rheumatoid arthritis (RA) vary. This study assessed real-world prevalence estimates of renal impairment, based on estimated glomerular filtration rate (eGFR), among commercially insured patients with RA in the United States (US).

Methods: In this retrospective cohort study, we used administrative claims data from the HealthCore Integrated Research Database (HIRD) between January 2013 and December 2018. Adult patients with ≥ 2 claims for RA and ≥ 2 serum creatinine (SCr) measurements ≥ 90 days apart on or after the index date were included. eGFR was calculated per the Modification of Diet in Renal Disease equation. Prevalence of eGFR-based renal impairment was estimated for the overall RA population and for two subgroups: patients on advanced therapies (biologic disease-modifying antirheumatic drugs/tofacitinib) and patients stratified based on health plan types.

Results: Among 128,062 patients with ≥ 2 RA claims, 42,173 had qualifying SCr measurements, 16,197 were on advanced RA therapies, and 4911 had Medicare Advantage or Supplemental plus Part D coverage. For the overall population and the subgroup on advanced therapies, mild renal impairment was observed in 52% and 51%, moderate renal impairment in 9% and 7%, and severe renal impairment in 0.5% and 0.3% of patients, respectively. Moderate and severe renal impairment was more prevalent in the Medicare Advantage/Supplemental plus Part D population compared to the commercial coverage population.

Conclusions: Approximately 7-10% of commercially insured adult patients in the US with RA had moderate or severe renal impairment. Assessment of renal function is an important consideration for safe treatment.