Prevalence, incidence and prognosis of chronic kidney disease classified according to current guidelines: a large retrospective cohort study of rheumatoid arthritis patients.

Background: The prevalence, incidence and prognosis of chronic kidney disease (CKD) have not been fully understood in rheumatoid arthritis (RA) patients.

Methods: A retrospective cohort study was performed in 1077 RA patients from July 2004 to June 2014. CKD was defined as either proteinuria ≥1+ or estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 or both, according to the current CKD classification with risk categories for future death, end-stage renal disease and cardiovascular disease. The cumulative incidence of mortality and CKD was analyzed using the Kaplan-Meier method. The association of each outcome with known risk factors was analyzed using multivariate Cox proportional hazards regression models. Hazard ratios (HRs) with 95% confidence intervals (CIs) for mortality and incidence of CKD were calculated for estimation.

Results: The mean follow-up period was 51.5 ± 39.6 months, and the cumulative mortality was 20.6% over 10 years. The prevalence of any CKD was 24.5% at enrollment. Preexisting CKD was significantly associated with future death [HR 1.64 (95% CI 1.05-2.57)]. This association was the most robust in very-high-risk CKD [HR 4.76 (95% CI 2.24-9.51)]. The cumulative incidence of CKD over time was 59.5% in 813 patients who did not have prior CKD. Aside from the commonly known risk factors, the use of prednisolone and nonsteroidal anti-inflammatory drugs increased the likelihood of death [HR 1.75 (95% CI 1.11-2.79)] and incident CKD [HR 1.44 (95% CI 1.13-1.86)].

Conclusions: The incidence of CKD increases over time among RA patients and prevalent CKD may be an insidious risk factor linked to increased mortality in RA patients.