Importance: It is necessary to determine whether psoriasis responds to methotrexate in the same manner in patients with and without psoriatic arthritis.
Objective: To evaluate the effectiveness and safety of methotrexate in treating patients with psoriasis with and without psoriatic arthritis.
Design, setting, and participants: In this prospective, single-arm, interventional study, a total of 235 patients with psoriasis, 107 without psoriatic arthritis and 128 with psoriatic arthritis who were receiving methotrexate therapy from April 1, 2015, to December 31, 2017, were recruited from the outpatient department of a hospital at a large Chinese university. There were no significant demographic or clinical differences between the subgroups with the exception of diabetes.
Interventions: A 12-week course of low-dosage oral methotrexate (7.5-15 mg weekly).
Main outcomes and measures: Changes in disease severity, adverse events, blood cell counts, and liver and renal function.
Results: A total of 235 patients with psoriasis (166 male [66.0%]; mean [SD] age, 49.6 [15.1] years) received methotrexate treatment for 12 weeks. The 90% reduction from baseline Psoriasis Area Severity Index response was significantly lower in patients with psoriatic arthritis than in patients without psoriatic arthritis at week 8 (4 0f 128 [3.1%] vs 12 of 107 [11.2%]; P = .02) and week 12 (19 of 128 [14.8%] vs 27 of 107 [25.2%]; P = .049). Furthermore, the incidence of adverse events, including dizziness (12 of 128 [9.4%] vs 1 of 107 [0.9%]; P = .007), gastrointestinal symptoms (32 of 128 [25.0%] vs 13 of 107 [12.1%]; P = .01), and hepatoxicity (34 of 128 [26.6%] vs 16 of 107 [15.0%]; P = .04), was significantly higher in patients with psoriatic arthritis than in patients without psoriatic arthritis. Methotrexate-induced elevation of alanine aminotransferase levels was associated with body mass index (mean [SD] body mass index, 26 [4] in patients with [P = .04] vs 26 [4] in those without [P = .005] psoriatic arthritis) and smoking (17 of 34 [50.0%] in patients with [P = .02] vs 9 of 16 [56.3%] in those without [P = .04] psoriatic arthritis).
Conclusions and relevance: In this study, methotrexate was well tolerated and effective in treating psoriasis. It was more effective, with fewer adverse effects, in patients with psoriasis who did not have psoriatic arthritis than in patients who presented with both psoriasis and psoriatic arthritis. Therefore, methotrexate can be recommended as first-line treatment for psoriasis without arthritis.