Long-Term Survival of Methotrexate as First-Line Therapy in Rheumatoid Arthritis, Psoriatic Arthritis and Undifferentiated Arthritis.

: In the era of biotechnological drugs, methotrexate (MTX) still represents the first-line treatment in chronic inflammatory arthritis, such as rheumatoid arthritis (RA), psoriatic arthritis (PsA), and undifferentiated arthritis (UA). The aim of our study was to evaluate the persistence of MTX as a first-line treatment in a group of patients with chronic inflammatory arthritis. : We conducted a retrospective analysis of a database of outpatients diagnosed with RA, PsA, or UA who visited our Rheumatology Clinic from January 2014 to January 2022. Key demographic and clinical data, including information on comorbidities and treatments, were routinely collected. Kaplan-Meier (KM) curves were used to determine the persistence of MTX during follow-up. : A total of 242 patients with chronic inflammatory arthritis who initiated MTX as first-line therapy and had available clinical data were included. Of these, 130 (53.7%) had RA, 82 (33%) had PsA, and 30 (16.3%) had UA. Overall, the survival rate of MTX at 24 months of follow-up was approximately 60%, while at 48 months and 96 months, it was 40% and 20%, respectively. A statistically significant difference was found between RA and PsA compared to UA (Chi-square test = 14.84; = 0.001). When comparing the KM survival curves of MTX between male and female patients, obese and non-obese individuals, as well as older (age ≥ 50 years) and younger patients (age < 50 years), no statistically significant differences were observed in any of the comparisons. : Our study confirmed the efficacy and overall safety of MTX in RA and PsA, with good persistence even over the long term.