High burden of infections in Indian patients with Idiopathic Inflammatory Myopathy: validation of observations from the MyoCite dataset

Objective To determine the prevalence, profile and predictors of infections in an Indian cohort with idiopathic inflammatory myopathies (IIM). Methods We reviewed the records of a retrospective cohort with IIM enrolled from consecutive patients being followed up in the clinic, and these constituted the observation cohort. A newly diagnosed inception cohort with IIM were followed prospectively as the validation cohort for confirmation of observations and comparison with the observation cohort. Results Among the 68 patients in the observation cohort (average age 33.4years, female:male 4.2:1), 37 (54.4%) experienced 54 infections between them; of these 54 infections, 21 (38.8%) were major and recurrent infections and they occurred in 11 patients (16.17%) over 3.08years. Tuberculosis was the most common infection (12, 22.2%), with a predominance of extrapulmonary forms. Serum protein [odds ratio (OR) 0.44], platelets (0.44) at disease onset and daily steroid dose (1.04) predicted major infections on multivariate analysis. A higher daily dose of steroids at first infection correlated with number of recurrent infections. The infection-free 1-year survival was 73.8%. Of the 70 patients in the validation cohort (average age 35.7years, female:male 3.7:1), 3 had myositis attributed to an infection. A similar proportion of the cohort experienced infections (22, 33.3%) with similar number of major (10, 45.4%) and recurrent (4, 18%) infections being recorded. The most common infection was community-acquired pneumonia, followed by tuberculosis, with serum albumin (OR 0.25) at disease onset being the only predictor. The one-year infection-free survival rate was 64.7%. Those who had a major infection had increased mortality at 1year, with a survival rate of 60%, compared with 89.09% in those without. In both cohorts, a daily prednisone dose >6.25mg predisposed to major infections. Conclusion Major and recurrent infections are common in Indian IIM patients and confer higher risk for future infections and lower survival. Respiratory and atypical bacterial infections such as tuberculosis occur throughout the disease course.