According to a study published in JAMA Dermatology, methotrexate is safe and effective as first-line treatment for patients with psoriasis. It is also more effective and better tolerated in patients without arthritis compared with patients with concomitant psoriatic arthritis.

The investigators of this prospective, single-center, observational study sought to compare the efficacy and safety of methotrexate to treat psoriasis in patients with and without psoriatic arthritis.

The study sample included 235 adults diagnosed with psoriasis recruited from a large university hospital in China: 128 participants with moderate-to-severe psoriatic arthritis and 107 without psoriatic arthritis. The participants all received a 12-week course of low-dose methotrexate therapy from April 2015 to December 2017. Severity and extent of psoriasis were assessed using the Psoriasis Area Severity Index and body surface area scores; blood cell counts, liver enzyme levels, and renal function were also measured at baseline and at weeks 4, 8, and 12. The primary outcomes of interest were changes in disease severity and adverse events.

Clinical and demographic differences between patient groups with and without psoriatic arthritis were not significant; however, the investigators noted that the psoriatic arthritis group had a higher rate of diabetes. The proportion of participants who achieved a 90% reduction in Psoriasis Area Severity Index scores from baseline to week 8 was significantly lower in patients with psoriatic arthritis vs patients without psoriatic arthritis (3.1% vs 11.2%; P =.02). This trend continued through week 12, with 14.8% of patients with psoriatic arthritis achieving a 90% reduction in scores vs 25.2% of patients without psoriatic arthritis (P =.049). At week 12, 41.4% of patients with psoriatic arthritis and 50.5% without (P =.19) achieved a 75% reduction in scores.

Most treatment-associated adverse events were reported as mild or moderate, and no participants dropped out due to severe adverse events. The incidence of adverse events was significantly higher in patients with psoriatic arthritis vs patients without psoriatic arthritis, including reports of dizziness (9.4% vs 0.4%; P =.007), gastrointestinal symptoms (25.0% vs 12.1%; P =.01), and hepatoxicity (26.6% vs 15.0%; =.04). A methotrexate-induced elevation of liver enzyme alanine aminotransferase was more frequent in patients with arthritis and was associated with increased body mass index and smoking in both patient groups.

Limitations to the study included a short treatment course of 12 weeks and a single-center setting, limiting the generalizability of the findings. Folic acid supplementation was not prescribed with treatment, and therefore, gastrointestinal symptoms may have been overestimated.

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Methotrexate to treat psoriasis was effective and well tolerated, however, it was less effective in patients with psoriatic arthritis. Additionally, more patients with arthritis reported adverse events, including dizziness and abnormal hepatic function. Risk factors of smoking and increased body mass index were associated with elevated alanine aminotransferase levels, which were significantly more frequent in patients with psoriatic arthritis. Therefore, methotrexate is recommended as first-line therapy for psoriasis patients without arthritis.

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Reference

Yan K, Zhang Y, Han L, et al. Safety and efficacy of methotrexate for Chinese adults with psoriasis with and without psoriatic arthritis [published online January 30, 2019]. JAMA Dermatol. doi: 10.1001/jamadermatol.2018.5194