PURPOSE: Myositis-associated interstitial lung disease (MA-ILD) significantly contributes to morbidity and mortality among patients with polymyositis or dermatomyositis. There is little quality evidence to guide therapy in these patients.
METHODS: In a retrospective cohort design, medical records of patients with ILD related to dermatomyositis or polymyositis that were seen in the ILD clinic of Emory University during 2005 through 2009 were reviewed. Apart from basic demographic details, a note was made of pulmonary function tests (PFTs), chest imaging as well as immunosuppressive medications administered (if any) over the first 12 months of each patient’s association with our ILD clinic.
RESULTS: In total, nine dermatomyositis and eight polymyositis cases were studied. The mean duration of respiratory symptoms prior to presentation at our clinic was 12 months. The mean initial FVC was 2.38L (mean percentage of predicted being 67.5%) and the initial FEV1 was 1.92L. The mean initial DLco was 13.8. Over the study time period, PFT variables deteriorated in 11 of the 17 cases; the other six saw a slight improvement. The FVC declined by 0.24L on average, the FEV1 by 0.19L and the DLco by 2.25. Each of our patients was on daily oral prednisone with a mean dose of 32 mg/day. Eleven of the patients also received azathioprine. PFT values were not statistically significant between the two groups. Neither radiographic progression nor mortality were noted in any of the patients during this time period.
CONCLUSIONS: In our experience, interstitial lung disease in patients with polymyositis-dermatomyositis was mild and progressed slowly (as measured by PFTs) in the setting of prednisone +/- azathioprine therapy. Lung imaging did not reveal evidence of progression during the course of our study.
CLINICAL IMPLICATIONS: In MA-ILD patients, it may be prudent to measure disease progression over a short time period (such as 12 months) via PFTs alone. Repeating chest imaging may not provide additional information.
DISCLOSURE: The following authors have nothing to disclose: Bilal Muzaffar, Majid Shafiq, Rabih Bechara, Esper Annette, Greg Martin, Jesse Roman
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