Absence of pulmonary fibrosis in patients with psoriatic arthritis treated with weekly low-dose methotrexate

To analyse pulmonary toxicity in psoriatic arthritis patients treated with weekly low-dose methotrexate.

A transversal study was carried out to analyse the findings on chest x-rays and high resolution computed tomography, and the results of pulmonary function tests in 27 Caucasian psoriatic arthritis patients treated with weekly low-dose methotrexate. None of them had previous recognized interstitial lung disease.

The median age of the patient cohort was 50 years (range 24-70 years) and the sex ratio was 20M/7F. 17 patients had previously used other disease-modifying antirheumatic drugs. The mean weekly dose of methotrexate was 8.46 mg (range 5-15 mg), the average treatment period was 52 months (range 3-240 months), and the median cumulative dose was 2241 mg (range 300-6520 mg). High resolution computed tomography failed to show alveolar or interstitial involvement in any patient. Diffusing lung capacity for carbon monoxide was mildly altered only in 2 cases. Pulmonary function tests did not show differences between patients with and without recognized risk factors for developing methotrexate-associated lung toxicity identified in rheumatoid arthritis patients (old age, diabetes, hypoalbuminemia, previous use of disease modifying antirheumatic drugs).

In this cohort of 27 psoriatic arthritis patients methotrexate was not associated with pulmonary fibrosis evaluated by means of sensitive imaging findings and pulmonary function tests.