Early Illness Features Associated With Mortality in the Juvenile Idiopathic Inflammatory Myopathies

Abstract

Objectives Because juvenile idiopathic inflammatory myopathies (JIIM) are potentially life-threatening systemic autoimmune diseases, we examined risk factors for JIIM mortality. Methods Mortality status was available for 405 patients (329 juvenile dermatomyositis [JDM], 30 juvenile polymyositis [JPM], 46 juvenile connective tissue disease–associated myositis [JCTM]) enrolled in nationwide protocols. Standardized mortality ratios (SMR) were calculated using United States population statistics. Cox regression was used to assess univariable associations with mortality, and random survival forest (RSF) classification and Cox regression for multivariable associations. Results Of 17 deaths (4.2% overall mortality), 8 (2.4%) were in JDM patients. Death was related to the pulmonary system, primarily interstitial lung disease (ILD), in 7 patients, gastrointestinal in 3, multisystem in 3, and of unknown etiology in 4 patients. The SMR for JIIM overall was 14.4 [95% confidence interval (CI) 12.2, 16.5] and 8.3 [95% CI 6.4, 10.3] for JDM. The top mortality risk factors in the univariable analysis included clinical subgroup (JCTM, JPM), anti-synthetase autoantibodies, older age at diagnosis, ILD and Raynaud’s phenomenon at diagnosis. In multivariable analyses, clinical subgroup, illness severity at onset, age at diagnosis, weight loss and delay to diagnosis were the most important predictors from RSF; clinical subgroup and illness severity at onset were confirmed by multivariable Cox regression. Conclusions Overall mortality was higher in JIIM patients, and several early illness features were identified as risk factors. Clinical subgroup, anti-synthetase autoantibodies, older age at diagnosis, and ILD are also recognized as mortality risk factors in adult myositis.

Brief Report: Association of Myositis Autoantibodies, Clinical Features, and Environmental Exposures at Illness Onset With Disease Course in Juvenile Myositis

“…The clinical utility of myositis-specific autoantibodies in predicting prognosis in both adult and juvenile onset myositis has been noted by others (1,15). …”

“…Juvenile dermatomyositis (JDM) is the most common clinicopathological form of JIIM. Additional phenotypes with higher morbidity and mortality are juvenile polymyositis (JPM), without the characteristic rashes of JDM, and juvenile connective tissue myositis (JCTM), in which patients meet the criteria for JIIM and at least one other autoimmune disease (1,2). The disease courses of JIIM can be distinguished into three types: monocyclic, polycyclic, and chronic (3,4).…”

Profile of Pediatric Idiopathic Inflammatory Myopathies from a Tertiary Care Center of Eastern India

“…The common causes of death are progressive pulmonary disease, gastrointestinal problems (hemorrhage, perforation, vasculopathy), multisystem and idiopathic [7,29]. In spite of best efforts of the authors 2 of the JDM and 1 of the OM patients died (overall n = 3; 27%).…”

Myositis registries and biorepositories

“…A large French national natural history study [62] of IBM revealed progressive functional disability but no overall increase in mortality. Predictors of mortality for polymyositis, dermatomyositis, and JDM have been determined and were found to be similar in different parts of the world and among phenotypes, with interstitial lung disease and the anti-synthetase autoantibodies among the risk factors predicting greater mortality [1**,37,67,82]. Classic epidemiologic investigations have been performed, deriving estimates of incidence and prevalence in national registries [3*,58], with documented increases in incidence over time for IBM in Australia and an increased prevalence of polymyositis and dermatomyositis in urban regions of Canada, for example [9,10*,97,129,138].…”

“…Clinical registries include national administrative efforts and health care systems’ tracking of medical utilization, costs, and outcomes, including such databases as the Social Security Death Index, from which mortality information may be gleaned [1**;2] or national health care registration systems that can be used to estimate disease prevalence in epidemiologic research [3*]. Registries may also include those that involve investigator-initiated research, with data collection that may include epidemiology, clinical features, outcomes, disease activity and damage assessments, and assessment of responses to therapies.…”