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

OBJECTIVES: To analyse pulmonary toxicity in psoriatic arthritis patients treated with weekly low-dose methotrexate.
METHODS: 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.
RESULTS: 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).
CONCLUSION: 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.