Prevalence of chronic kidney disease and administration of RA-related drugs in patients with RA: The NinJa 2012 study in Japan

OBJECTIVES: To estimate the prevalence of chronic kidney disease in patients with rheumatoid arthritis (RA) and the administration of disease-modifying anti-rheumatic-drugs (DMARDs), using data from the National Database of Rheumatic Disease by iR-net in Japan (NinJa) 2012 study. METHODS: From a total of 11,940 RA patients, 7135 who underwent an estimated glomerular filtration rate (eGFR) test were studied. Renal dysfunction staging was assessed using Japanese eGFR equations and classified according to the Kidney Disease Improving Global Outcomes 2012 clinical practice guideline. RESULTS: The prevalence of GFR stages was as follows: stage G1, 25.4%; stage G2, 55.9%; stage G3, 17.5%; stage G4, 0.8%; and stage G5, 0.2%. Overall, 92.7% of patients received at least one DMARD. Sulfasalazine, tacrolimus, and biologics (except inflixmab) were administered in all GFR stages. Methotrexate was not prescribed in patients with stage G5, but methotrexate 3.5 mg/week (mean) was prescribed in four patients (6.8%) with stage G4. Non-steroidal anti-inflammatory drugs and glucocorticoids were prescribed in 40.5% and 43.7% of patients, respectively. CONCLUSION: The prevalence of kidney disease in this large sample of RA patients was higher than that in the general population, and the results suggest that RA patients with renal dysfunction require careful drug selection.