High Prevalence of Active Tuberculosis in Adults and Children with Idiopathic Inflammatory Myositis as Compared with Systemic Lupus Erythematosus in a Tuberculosis Endemic Country: Retrospective Data Review from a Tertiary Care Centre in India.

Aim: Infections are the leading cause of morbidity and mortality in idiopathic inflammatory myositis (IIM) with India being endemic for Tuberculosis (TB). We compared and contrasted the prevalence, clinical profile and outcomes of active TB in IIM with systemic lupus erythematosus (SLE).

Methods: Medical records were reviewed for adults and children with IIM (Bohan and Peter criteria) and SLE (ACR criteria) at a tertiary care hospital in India from January 2015 to October 2017. Follow-up was recorded until February 2020 for all those who had developed active TB.

Results: Of 167 (132 adults and 35 juvenile) IIM and 280 (131 adults and 149 juvenile) SLE, active TB occurred in 24 (14.4%) IIM (22 (16.7% of 132) adults; 2 (5.71% of 35) juvenile) and 18 (6.4%) SLE [(8 (6.1% of 131) adults; 10 (6.7% of 149) juvenile, p-value < 0.01]. Patients with IIM had higher odds of developing TB as compared with SLE [OR 2.24 (CI 1.5-5.5), p=0.007]. The risk of developing active TB was 68-fold and 30.4-fold higher in patients with IIM and SLE, respectively, as compared with the general population. Extrapulmonary forms were more common (14/24). Nearly half developed TB during active IIM, at a glucocorticoid dose of 0.25 (0-1.5) mg/kg/day. Over a follow-up duration of 27 months (8-184), all were cured of TB, though prolonged course of anti-tuberculous treatment was required in 25%, and five IIM relapsed during treatment.

Conclusion: Patients with IIM have increased risk of active TB, with common extrapulmonary forms, slow response, and relapses during treatment.