Background Methotrexate pneumonitis (MTX-P) is most frequently seen within the first year of treatment1 and is best avoided in established cases of Interstitial Lung disease (ILD). BSR recommends that if pre-treatment Chest X-Ray (CXR) is abnormal then consider High Resolution Computed Tomography (HRCT) and Pulmonary Function tests (PFTs) to ascertain TLCO, but TLCO may be more sensitive in some cases. Recent studies have suggested that incidence of MTX-P is not as common as previously thought2,3. Clinical presentation is usually of male smokers with pre-existing lung disease presenting with respiratory symptoms and signs and raised ESR4,5.
Objectives To study if spiromtery alone, rather than full PFTs would be sufficient in patients without risk factors when commencing Methotrexate
Methods In August 2013 we carried out an audit of 58 patients who were on Methotrexate for at least greater than 6 months for any Autoimmune Inflammatory Rheumatic Disease (AIIRD).
Results 43 patients were between 31-70 years of age, range being 15-80 years. 22 were males and 36 females. 36 patients had RA, 7 had Psoriatic arthritis and the rest had some other AIIRD. Patients audited had started MTX from 1996 up to 2013 (show table). 49 patients were on MTX for more than 12 months. Baseline CXR was done in 46 patients. 12 patients each were either current or ex-smokers. 29 patients were not checked for crackles in chest at the time of MTX commencement. Among the rest, only one had crackles. Two patients complained of breathlessness on MTX commencement. Baseline PFTs were done in 39 patients but only 34 had their transfer co-efficient (KCO) checked. One patient had restrictive picture on PFTs and ten had an obstructive picture. KCO was less than 70% in 5 patients who were all current or ex-smokers. HRCT was performed in 4 of these. One patient, who was a smoker and had obstructive PFTs, had fibrosis with alveolitis related to RA and MTX was stopped after initial few doses. MTX was started in the other three. Repeat PFTs were required in three patients for respiratory symptoms and as KCO was >70%, MTX was continued in all three. Two patients, who had not had a baseline PFT, had one, ten years after being on MTX and it was continued in both of them.
Conclusions None of the patients developed MTX-P and only one had ILD related to RA. Our results suggest that if we just do a baseline spirometry when commencing MTX, except in patients with risk factors, then we can save on National Health Service budget, as the cost of full PFTs is £250/– and of spirometry alone is £ 60/–2, but we ideally need larger numbers to study to make final conclusions
Imokawa S, Colby TV, Leslie KO, Helmers RA. Methotrexate Pneumonitis: review of the literature and histopathological findings in nine patients. Eur Respir J 2000;15:373–81
Sathi N et al. How common is methotrexate pneumonitis? A large prospective study investigates. Clin Rheumatol. 2012 Jan;31(1):79-83
Salliot C et al. Long-term safety of methotrexate monotherapy in patients with rheumatoid arthritis: a systematic literature research. Ann Rheum Dis. 2009 Jul;68(7):1100-4
Searles G et al. Methotrexate pneumonitis in rheumatoid arthritis: potential risk factors. Four case reports and a review of the literature. J Rheumatol. 1987 Dec;14(6):1164-71
Hargreaves MR et al. Acute pneumonitis associated with low dose methotrexate treatment for rheumatoid arthritis: report of five cases and review of published reports. Thorax. 1992 Aug;47(8):628-33.
Disclosure of Interest None declared