High early mortality in idiopathic inflammatory myopathies: results from the inception cohort at a tertiary care centre in northern India.

Abstract

We determined the mortality along with the proportion of disease related adverse events measured individually and by a composite adverse outcome (devised by including deaths, disability, relapses and minimal response) and its predictors in an inception cohort of idiopathic inflammatory myopathies (IIM). IIM from the MyoCite cohort (December 2017-19) were reviewed for early outcomes (mortality, IMACS core set). Comparisons were drawn between those meeting the primary and secondary outcomes. Of 70 patients [62 adults, M:F = 1:4.8, age 43 (28.5-51) and eight children, M:F = 1:1, 14.5 (8.8-16)], dermatomyositis (DM) was the most common subset [29 (41.4%) adults; 7 (87.5%) children]. Over 10 (4-15) months, 10 (15.2%) died and four polymyositis were reclassified. One-year survival for anti-melanoma differentiation antigen 5 (MDA5) subtype was 30% and anti-synthetase syndrome (ARS) subtype was 75%. Overall, lower respiratory infections were the most common cause of death [n = 3 (30%)] followed closely by malignancy and rapidly progressive interstitial lung disease (RP-ILD). Amongst survivors, a major IMACS response was recorded in 54.5% adults and 100% children. Thirty per cent suffered from moderate to severe disability and 16.7% experienced relapses. Overall, two-thirds accrued the composite adverse outcome. On multivariate analysis, older age and anti-MDA5 predicted mortality. Arthritis, rash and positive ANA reduced and anti-MDA5 increased the risk for the composite adverse outcome. Indian patients with IIM suffer high early mortality attributable to infection, cancer and RP-ILD, calling for high vigilance post diagnosis. Autoantibodies and certain clinical features identify risk for composite adverse outcomes.