Background/Purpose: The diagnosis of interstitial lung disease (ILD) is comprised of a large group of respiratory disorders. ILD can lead to scarring of lung tissue. Factors such as environmental exposure, certain diseases (e.g. rheumatoid arthritis) and medications have been implicated. Methotrexate (MTX) has been identified as one of the medications with potential to cause ILD although the exact incidence of MTX-specific ILD remains unknown.

Salliot et al conducted a systematic literature review to assess the long-term implications of MTX therapy. The results of 21 prospective studies (N= 3463) were combined to determine the frequency of adverse events (AEs). Eighty-four patients (2.4%) experienced respiratory-related AEs; The AEs experienced by 15 of those patients were attributed to MTX pneumonitis. Conway et al also conducted a systematic literature review to identify the risk of pulmonary disease in patients prescribed MTX. Seven studies were included in the review (N=1630) and 504 respiratory-related AEs were documented. MTX was not found to be associated with an increased risk of respiratory AEs. Burmester et al conducted a post hoc analysis including data from two studies: CONCERTO (N= 395) and MUSICA (N= 309), chronic dry cough as the only respiratory AE was 0.8% and 0.6% respectively. This study was conducted to determine how many patients prescribed MTX in the UF Health Jacksonville Rheumatology Clinics have completed chest imaging and if any patients were diagnosed with ILD.

Methods: Data was obtained from the electronic health record (EHR) from September 1, 2014 to September 30, 2017. Patients prescribed MTX from UF Health Jacksonville Rheumatology clinics, had chest imaging [chest x-ray, chest CT scan or chest MRI] and a diagnosis of ILD [ICD -10 code J84.9] were included. Patients with the diagnosis of ILD were further evaluated to determine the MTX dose and if MTX discontinuation occurred.

Results: A total of 701 patients were prescribed MTX during the evaluation period. Chest imaging was obtained on 137 patients (19.5%) and of these patients, 80 patients had a chest x-ray. Initially, 7 patients (0.9%) were identified to have the intended ICD-10 code J84.9 for ILD. On further evaluation, it was discovered that an additional ICD-10 code J84.10 for pulmonary fibrosis (PF) was included in the data, which accounted for 3 of the initial 7 ILD patients. Therefore, 4 patients (0.6% of 701 patients) had a diagnosis of ILD. Of the 4 ILD patients, MTX was discontinued in two patients. MTX was discontinued in all 3 patients with PF.

Conclusion: Based on the results of this retrospective study and low incidence of ILD cited in literature, it is difficult to justify routine chest imaging for MTX monitoring. Almost 20% of the patients prescribed MTX also obtained chest imaging during the evaluation period. A chest x-ray was the most common type of imaging performed in all patients prescribed MTX during the evaluation period. Four of 701 patients (0.6%) evaluated had a diagnosis of ILD based on the problem list. A limitations of this study was using only the ILD specific ICD-10 code to identify patients.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/methotrexate-quality-improvement-project-at-uf-health-jacksonville-rheumatology-clinics/