Background/Purpose: Chronic kidney disease (CKD) is a  comorbidity that may affect patients with rheumatoid arthritis (RA). CKD restricts the use of disease modifying anti-rheumatic drugs (DMARDs) e.g. methotrexate, limiting the ability to control disease activity. We utilized the Veterans Affairs Rheumatoid Arthritis Registry (VARA), an observational chronic disease cohort at 11 Veterans Affairs (VA) medical centers where RA disease activity measures are recorded longitudinally to examine the frequency and progression of CKD in patients with RA..

Methods: VA patients enrolled in the VARA registry were eligible for analysis. This database was used to extract patient demographics and measures of RA disease activity and severity. Administrative data obtained from the VA corporate data warehouse (CDW) was collected for serum creatinine, weight, select comorbidities including ischemic heart disease (IHD), diabetes mellitus (DM) and hyperlipidemia. Creatinine clearance (CrCl) was calculated for each patient using the CKD-EPI creatinine equation and severity of CKD staged. Chi square and analysis of variance were used to compare categorical and continuous variables respectively between the stages of CKD. Longitudinal data from VARA and CDW were collected to examine the progression of CKD from stage II or better to Stage 3 or worse. A cox regression analysis was used to examine the effect of patient demographics and RA characteristics on the progression of CKD.

Results: There were 1577 RA patients available for study, 473 (30.1%) had CKD stages III to V, most, 399 (25.1%) had stage III. CKD was associated with male gender, older age and African American (AA) race (Table1). There were no differences in the presence of RF, anti-CCP antibodies, radiographic changes or the use of DMARDs, however patients with CKD were more likely to have subcutaneous (SC) nodules. Greater disease activity 28- C-reactive protein (DAS28-CRP) scores were reported in patients with stage IV and V CKD [4.0 (1.0) and 4.7 (1.4) respectively] compared with stage I and II [3.8 (1.2) and 3.6 (1.3) respectively] p < 0.0001. Comorbidities, DM, IHD and hyperlipidemia were independently associated with CKD (p < 0.0001). Predictors of progression of CKD included AA race HR = 2.0; CI = 1.48, 2.69, physician global assessment (PGA) HR = 1.36 (CI = 1.03, 1.80), DAS28-CRP, HR = 1.45 (CI = 1.10, 1.91) and IHD, HR = 1.63 (CI = 1.24, 2.16). Age, radiographic erosions, SC nodules and multi-dimensional health assessment questionnaire (MD-HAQ) were not associated with progression of CKD

Conclusion: CKD was not infrequent in US veterans with RA and was associated with older age, AA race, smoking, IHD, rheumatoid nodules and greater disability and disease activity. The predictors for the progression of CKD included AA race, PGA, DAS28-CRP and IHD. RA patients with early CKD should be monitored for disease progression and treatment of both CKD and RA optimized.