Background/Purpose: Interstitial lung disease (ILD) can affect up to 30% of the patients with idiopathic inflammatory myositis (IIM) and contributes significantly towards morbidity and mortality rates. The clinical and radiographic manifestations of IIM-ILD are variable in the affected population. The objective of our study was to recognize the patterns of IIM-ILD and determine the treatment outcomes for these patients specific to the rural Appalachian population of West Virginia.

Methods: A retrospective observational cross-sectional study was performed between January 1, 2012 through August 31, 2022, at a medium sized academic medical facility located in the WV rural Appalachia. 115 patients with IIM were identified through electronic medical record system. Out of these, 29 patients who had coexisting ILD based on radiographic findings and pulmonologist evaluation were included for the final analysis.

Results: Majority of the patients were females (n=22, 76%), never-smokers (n=19, 65%), and had a mean age of 60.17 + 12.92 years. Dyspnea (n=24, 83%) was the most common presenting symptom with mean modified Medical Research Council (mMRC) scale of 2 + 1.2. The mean duration of symptoms at first encounter was 4.57 + 6.66 years. The most common IIM phenotypes were dermatomyositis (n=15, 52%) and polymyositis (n=8, 27.6%). In patients with available serology testing (n=20), anti-Jo1 was present in 55% of the affected population(n=11). Radiographic patterns at presentation (n=27) were indeterminate for usual interstitial pneumonia (UIP) (n=12, 44%), non-specific interstitial pneumonia (NSIP) (n=5, 18%), and UIP (n=3, 11%). Treatment modalities included prednisone (n=20, 69%), azathioprine (n=14, 48%), mycophenolate mofetil (n=13, 45%), and nintedanib (n=2, 7%). Data for mMRC scale, computed tomography (CT), and pulmonary function testing (PFT) before and after treatment was available for 19, 17 and 18 patients respectively. mMRC score improved or remained stable in 89% of patients post treatment (n=17). Similarly, CT findings and PFT improved or remained stable in 59% (n=10) and 67% (n=12) of the patients. Mortality rate during the study period was 21% (n=6).

Conclusion: Dermatomyositis was the most common phenotype and anti-Jo1 was the most observed antibody associated with ILD. Similar findings were reported in larger retrospective cohort studies. The most common radiographic pattern in our cohort was indeterminate for UIP compared to other cohorts with NSIP being the predominant CT finding. While comparing the progression of ILD with other studies based on presenting symptoms, radiographic findings and PFT results, a higher proportion of patients with stable and improved ILD was observed in our study. Despite improvement in the pulmonary disease with treatment, mortality rates were remarkably higher in this cohort compared to other ILD centers. Multiple extra-pulmonary factors have been associated with poor prognosis in IIM-ILD, as such, the increased mortality in our cohort may be due to non-pulmonary causes. Further prospective cohort studies are required to evaluate predictors of mortality in IIM-ILD in this region.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/characteristics-and-outcomes-of-idiopathic-inflammatory-myositis-associated-interstitial-lung-disease-in-rural-appalachia/