LAUSR

Background Methotrexate (MTX) remains the favoured disease-modifying anti-rheumatic drug for the treatment of rheumatoid arthritis (RA) and is frequently used in other inflammatory conditions. However, side effects are frequent and toxicity is of concern, especially since MTX-induced pulmonary side effects, including pneumonitis, are potentially fatal. Estimates of MTX-induced pneumonitis in the literature range from 0.3% to 7.5% of exposed cases (Barrera et al., 1994 Kremer et al., 1997). Objectives We aimed to identify and characterise MTX-induced lung injury in patients exposed to low-dose MTX at the Rheumatology Division of the Kantonsspital Aarau, Switzerland. Methods The revised diagnostic criteria for adverse pulmonary events due to MTX treatment as defined by Kremer et al 1997 were used to categorise MTX-induced lung injury. The electronic patient files of the Rheumatology Division are stored in a NoSQL-database (MongoDB), which is fully addressable by the Solr search platform (Apache Lucene). The entire database was searched for terms associated with methotrexate exposure and potential pulmonary side effects. Results Of 9’550 cases, 11 fulfilled the criteria for definite MTX-induced pulmonary injury, while three additional patients could be classified as suffering from probable MTX-induced pulmonary side effects. To determine the number of exposed cases, the case files were queried for the mention of MTX and related terms. 1’947 case files contained a reference to MTX. In a random sample of 395 of these cases, an exposure to MTX was verified in 328 (83%). Assuming a calculated exposure of 1’639 cases, MTX-induced lung injury was present in 0.85%. Conclusions In a comprehensive survey of patients exposed to MTX in a fully searchable routine clinical database, MTX-induced pulmonary injury occurred in a low frequency. References [1] Barrera P, Laan RF, van Riel PL, Dekhuijzen PN, Boerbooms AM, & van de Putte LB. Methotrexate-related pulmonary complications in rheumatoid arthritis. Ann Rheum Dis1994;53(7):434–439. [2] Kremer JM, Alarcon GS, Weinblatt ME, Kaymakcian MV, Macaluso M, Cannon GW, et al. Clinical, laboratory, radiographic, and histopathologic features of methotrexate-associated lung injury in patients with rheumatoid arthritis: a multicenter study with literature review. Arthritis Rheum1997;40(10):1829–1837. Acknowledgements Urs Rutschi, Stefan Hubeli, Alex Souza, Iterata AG, Gränichen, Switzerland, for assistance with data extraction strategies. Disclosure of Interest None declared