#284 Risk of dose-dependent methotrexate therapy on renal functions in patients with rheumatoid arthritis

Abstract

Abstract Background and Aims Methotrexate is often used as first-line therapy for RA because of its proven efficacy, good safety profile, and low cost. The importance of MTX also comes from the fact that in combinatory treatments, the efficacy of bDMARDs or tsDMARDs is always higher when these drugs are combined to MTX, suggesting making MTX at the base of any conventional treatment of RA. Although renal impairment is a major concern in patients taking high-dose MTX for the treatment of malignancy, it has not been fully examined in RA patients treated with low-dose MTX, so we aimed at studying the dose- dependent effects of MTX on renal function and creatinine clearance. Method Three hundred and sixty adult RA patients, regularly attending rheumatology OPC for regular follow up participated in this retrospective cohort study. Young children, patients with any degree of renal impairment and other rhematic diseases were excluded. Serum creatinine and creatinine clearance were followed up at 1 year and 3 years of different doses of MTX therapy, and results were compared to baseline levels. Results Patients’ ages had a mean of 44.60 years, with most being females (80.6%). Range of disease duration was 2-34 years with the mean of 9.93 years. Most of the patients had significant disease activity, where 36.4% had moderate activity and 26.1% of them had high disease activity according to DAS 28 score. We noticed a significant decline of the creatinine clearance at 1 & 3 years follow up regardless the MTX dose used (P-value: ≤0.001 for both). Conclusion We may conclude that MTX therapy has a potential nephrotoxic effect regardless the dose or the duration of therapy, mandating a close monitoring of renal functions for patients maintained on the drug.