Prognostic factors of idiopathic inflammatory myopathies complicated with interstitial lung disease: protocol for a systematic review and meta-analysis.

INTRODUCTION: Idiopathic inflammatory myopathies may be an overlapping disease complex. Although interstitial lung disease affects the mortality and the morbidity of the disease, a clinical course and the prognosis of the disease complicated with interstitial lung disease are diverse among individuals and prognostic factors have yet to be clarified. This article aims to report the rationale and the methodology of a future intended systematic review and meta-analysis of prognostic factors of idiopathic inflammatory myopathies complicated with interstitial lung disease.

METHODS AND ANALYSIS: Participants are eligible if they are diagnosed as polymyositis/dermatomyositis, clinically amyopathic dermatomyositis or antisynthetase syndrome complicated with interstitial lung disease. Primary outcomes are all-cause and pulmonary-cause mortality and secondary outcomes include a progression of the disease and a deterioration of health-related quality of life. All primary studies of any design aside from case reports or case series are included. 2 reviewers will search electronic databases such as the MEDLINE, the EMBASE and the Science Citation Index Expanded and extract relevant data independently. A risk of bias in individual studies is evaluated based on the Quality in Prognostic Studies tool. Meta-analysis will be conducted if 3 or more studies are available for each outcome and pooled effects will be presented by the odds ratio (OR). Where combining data is inappropriate due to a small number of studies or substantial heterogeneity, the result is reported qualitatively. Subgroup and sensitivity analysis are also considered based on clinical and methodological differences such as clinical manifestations, study designs and the quality of studies. The evidence level is assessed following the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) method.

ETHICS AND DISSEMINATION: This study raises no ethical issues as it is based on the findings of previously published articles. The result will be reported in a peer-reviewed medical journal.

TRIAL REGISTRATION NUMBER: CRD42016036999.