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Low-dose methotrexate may cause air trapping in patients with rheumatoid arthritis
C S Dayton1, D A Schwartz, N L Sprince
1Department of Internal Medicine, Department of Veterans Affairs Medical Center, Iowa City, Iowa.
Abstract:
Both rheumatoid arthritis (RA) and methotrexate (MTX) are reported to be associated with the development of pulmonary disease. To determine whether MTX enhanced the risk of developing abnormalities in pulmonary function in patients with RA, we prospectively studied 31 subjects (12 male, 19 female) with the diagnosis of classic RA for an average period of 4.4 yr (range, 1 to 5 yr). Each subject was placed on low-dose weekly MTX (mean 17 mg, range 2.5 to 40) for control of RA symptoms. Other medications included non-steroidal anti-inflammatory agents and prednisone if required for control of arthritis symptoms. No other immunosuppressive therapy was used. Each subject was evaluated by pulmonary function tests (PFT) and chest X-ray initially, and at 1, 2, 3.5, and 5 yr. Chest X-rays obtained initially and at the end of the study period were found to be normal. The percent predicted values for initial PFTs in the study group were within the normal range. From the beginning to the end of the observation period, the following mean changes in lung function were observed: 1.9% increase in TLC, 5.1% increase in residual volume (RV), 1.8% increase in FVC, 0.71% decrease in FEV1, 14.7% improvement in alveolar-arterial oxygen (A-aO2) difference, and a 12.7% increase in single-breath diffusing capacity (DLCO). To determine whether MTX (average dose, weekly dose, or cumulative dose) was significantly related to changes in pulmonary function, we used multivariate techniques to control for the initial measure of lung function while assessing the relationship between MTX and the subsequent measures of lung function.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Methotrexate (MTX) did not appear to worsen pulmonary function in rheumatoid arthritis (RA) patients. This study found no significant negative impact of MTX on lung function tests over five years.
Area of Science:
- Rheumatology
- Pulmonology
- Pharmacology
Background:
- Rheumatoid arthritis (RA) and methotrexate (MTX) are independently linked to pulmonary disease.
- The specific impact of MTX on pulmonary function in RA patients requires further investigation.
Purpose of the Study:
- To prospectively evaluate if MTX use exacerbates pulmonary function abnormalities in patients diagnosed with RA.
- To assess the relationship between MTX dosage (average, weekly, cumulative) and changes in pulmonary function.
Main Methods:
- A cohort of 31 RA patients were monitored for an average of 4.4 years.
- Patients received low-dose weekly MTX for RA symptom management.
- Pulmonary function tests (PFTs) and chest X-rays were conducted at baseline and multiple follow-up intervals.
Main Results:
- Chest X-rays remained normal throughout the study period.
- Initial PFTs were within the normal range for all participants.
- Minor changes in lung function were observed, including a slight increase in TLC, RV, FVC, and DLCO, and a small decrease in FEV1 and A-aO2 difference.
- Multivariate analysis did not reveal a significant relationship between MTX exposure and changes in pulmonary function.
Conclusions:
- Low-dose weekly MTX therapy does not appear to significantly impair pulmonary function in patients with rheumatoid arthritis.
- Long-term monitoring showed no detrimental effects of MTX on lung function parameters in this RA cohort.