BOSTON – It’s time to test whether methotrexate is really up to snuff as first-line therapy for psoriatic arthritis, Canadian investigators say.
They base that recommendation on findings from a retrospective study showing that fewer than 18% of patients with psoriatic arthritis treated with methotrexate achieved minimal disease activity (MDA) after 6 months.
They also found evidence to suggest that physicians may overestimate the benefits of methotrexate for psoriatic arthritis.
“Physician-dependent measures reveal good response to methotrexate at 6 months, but patient-reported measures are less responsive, possibly due to side effects, back pain, disease, [and/or] disability,” said Dr Barry J. Sheane of the division of rheumatology in the department of medicine at the University of Toronto.
The data on the effects of methotrexate in psoriatic arthritis are considerably less impressive than are those seen with tumour necrosis factor–alpha inhibitors (TNFi), Dr Sheane said. For example, at 24 weeks, 39% of patients treated with adalimumab (Humira) and 52% treated with infliximab (Remicade) had achieved MDA, he noted.
“We suggest that a randomized controlled trial of methotrexate compared to a TNF inhibitor is warranted,” Dr Sheane said at the annual meeting of the American College of Rheumatology.
He and his colleagues reviewed records on 204 consecutive patients treated for psoriatic arthritis with methotrexate from January 2004 through April 2014. The patients, who had a mean duration of psoriatic arthritis of 6.2 years, were all naive to biological antirheumatic drugs and were initiating methotrexate therapy.
Of the 204 patients, 167 had data sufficient for a 6-month analysis.
The investigators defined MDA after 6 months on methotrexate, the primary endpoint, as the presence of at least five out of the following seven domains: 0-1 tender joints, 0-1 swollen joints, Psoriasis Area Severity Index (PASI) 1 or less or body surface area involved 3% or less, 0-1 tender entheseal points, Health Assessment Questionnaire (HAQ) score of 0.5 or less, patient global disease activity Visual Analog Scale score of 20 or lower, and patient pain Visual Analog Scale score of 15 or lower.
They found that 17.4% of patients (29 of 167) met the physician-rated criteria for MDA at 6 months, even though 82.6% of the patients (138) had a PASI score of 1 or lower, and 58.1% (97) had a swollen joint count of 1 or fewer.
When the patients were asked for their assessment of global disease activity, 13.2% (22) rated disease activity with a prespecified score of 20 or lower. Only 12% of patients (20) reported an HAQ score of 0.5 or less.
The mean methotrexate dose was similar between patients who achieved MDA (17.8 mg/week) and those who did not (17.3 mg/week). The median dose was 17.5 mg/week in each group.
After controlling for sex, baseline sacroiliitis, and duration of psoriasis and psoriatic arthritis at the start of methotrexate in a multivariate model, the authors found that only dactylitis, inflammatory back pain, and mechanical back pain were significantly associated with a lower probability of patients reaching MDA. The variables that did not prove to be associated with achieving MDA after 6 months on methotrexate included erythrocyte sedimentation rate, presence of nail disease, number of clinically damaged joints, and body mass index.
The study was internally funded. Dr Sheane reported having no relevant disclosures.
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