Background/Purpose: Clinical management of rheumatoid arthritis (RA) must consider patient renal function, particularly for medications that rely on renal clearance and require dose adjustment or restriction in the presence of renal impairment. However, estimates of the prevalence of renal impairment/chronic kidney disease (CKD) among patients with RA vary widely (5-50%).¹ This study used the Modification of Diet in Renal Disease (MDRD) equation to calculate the prevalence of estimated glomerular filtration rate (eGFR)-based renal impairment among US patients with RA in a commercially insured population, with the goal of providing current real-world data to inform RA treatment decisions in cases where such decisions may be impacted by CKD.

Methods: Claims data from the HealthCore Integrated Research Database (HIRD^®) from January 2013 through December 2018 were used. All adult patients with ≥2 claims with diagnosis codes for RA were included in the study, with index date set as the earliest occurrence of an RA claim. All patients had to have ≥2 serum creatinine (SCr) laboratory measurements ≥90 days apart on or after the index date. Prevalence of eGFR-based renal impairment, including by severity category (i.e., mild, moderate, severe; see Table 1 for definitions), was calculated based on the MDRD equation (as race is a component of the MDRD equation, but is not collected in the database, individuals were designated as non-black for purposes of the calculation). Patients with conflicting severity categories based on their 2 SCr measurements were classified into the less-severe category. Possible variations in prevalence for patients on advanced therapies (biologic DMARDs or tofacitinib) were explored in subgroup analysis.

Results: There were 152,090 adult patients with RA identified in the HIRD®, with 128,062 (84%) meeting the criteria for inclusion in the study. Of these, 42,173 (33%) had ≥2 qualifying SCr laboratory results and 16,197 (13%) also initiated advanced RA therapies. Mean age was 56 years; 76% of patients were female. In this population, the estimated prevalence of renal impairment by severity is approximately 52% for mild, 9% for moderate, and < 1% for severe (Table 1). Prevalence was slightly lower among patients initiating advanced therapy. Prevalence remained relatively consistent from 2013 to 2018 (Figure 1).

Conclusion: Among commercially insured US adults with RA with ≥2 SCr results, approximately 7-10% of patients have moderate or severe CKD (eGFR < 60 mL/min/1.73m²) that might merit dose adjustment of RA medication. Prevalence in this population was stable from 2013 to 2018. While the reported prevalence of renal impairment may tend to underestimate true prevalence due to all patients being covered by commercial insurance, it highlights that renal monitoring, DMARD dose adjustment and potential for drug toxicity remain important considerations for approximately 10% of RA patients.  

Reference: (1) Couderc M, et al. Arthritis Care Res. 2016;68:638-44.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/prevalence-of-renal-impairment-in-a-us-rheumatoid-arthritis-population/