We previously reported that low-dose methotrexate (MTX) was associated with an increased risk of pulmonary adverse events (AEs) in a large randomized, placebo-controlled trial. Herein, we report details on the predictors and severity of pulmonary AEs.
We conducted a prespecified analysis of pulmonary AEs in the Cardiovascular Inflammation Reduction Trial. Adults with known cardiovascular disease and diabetes/metabolic syndrome were randomly allocated to receive low-dose MTX (target dose 15-20 mg/week) or placebo after a 6-8-week open-label run-in phase in which all patients received low-dose MTX. Individuals with systemic inflammatory diseases were excluded. Pulmonary AEs were adjudicated in a blinded manner. We described severe pulmonary AEs and examined associations of baseline characteristics with pulmonary AEs in patients receiving low-dose MTX.
A total of 2,391 subjects were randomized to receive low-dose MTX and 2,395 to receive placebo. There were 13 severe pulmonary AEs (0.5%) and 7 cases of possible pneumonitis (0.3%) in the low-dose MTX group, compared to 8 (0.3%) and 1 (<0.1%), respectively, in the placebo group. Among those randomized to receive low-dose MTX, risk factors for any pulmonary AE included female sex (hazard ratio [HR] 1.69 versus male sex [95% confidence interval (95% CI) 1.16-2.45]), white race (HR 2.35 versus other race [95% CI 1.03-5.36]), and insulin use (HR 1.60 versus non-use [95% CI 1.11-2.30]). The only risk factor for severe pulmonary AEs was older age at baseline (HR 1.09 per year increase [95% CI 1.02-1.16]).
In this large placebo-controlled trial, pulmonary AEs, including possible pneumonitis, were uncommon but were more likely to occur in those randomized to receive low-dose MTX. White race, older age, male sex, and insulin use were associated with an increased risk of pulmonary AEs in those receiving low-dose MTX.