Objective To clarify prognostic factors for idiopathic inflammatory myopathy (IIM)-associated interstitial lung disease (ILD).
Design Systematic review and meta-analysis using the Grades of Recommendation, Assessment, Development and Evaluation system.
Data sources Medline, EMBASE and Science Citation Index Expanded were searched through 9 August 2018.
Eligibility criteria for selecting studies The review includes primary studies addressing all-cause mortality of IIM-associated ILD. Potential prognostic factors were any clinical information related to the outcome.
Data extraction and synthesis Two reviewers extracted relevant data independently and assessed risk of bias using the Quality in Prognostic Studies tool. Meta-analysis was conducted using a random effects model and if inappropriate the results were reported qualitatively. Prognostic factors were determined based on statistically significant results derived from multivariate analysis.
Results Of a total of 5892 articles returned, 32 were deemed eligible for analysis and cumulatively, these studies reported 28 potential prognostic factors for all-cause mortality. Each study was subject to certain methodological constraints. The four prognostic factors, which demonstrated statistically significant results on both univariate and multivariate analyses, were as follows: age (MD 5.90, 3.17–8.63/HR 1.06, 1.02–1.10 and 2.31, 1.06–5.06), acute/subacute interstitial pneumonia (A/SIP) (OR 4.85, 2.81–8.37/HR 4.23, 1.69–12.09 and 5.17, 1.94–13.49), percentage of predicted forced vital capacity (%FVC) (OR 0.96, 0.95–0.98/HR 0.96, 0.93–0.99) and anti-Jo-1 antibody (OR 0.35, 0.18–0.71/HR 0.004, 0.00003–0.54) (univariate/multivariate, 95% CI). Other prognostic factors included ground glass opacity/attenuation (GGO/GGA) and extent of radiological abnormality. The quality of the presented evidence was rated as either low or very low.
Conclusions Older age, A/SIP, lower value of %FVC, GGO/GGA and extent of radiological abnormality were demonstrated to predict poor prognosis for IIM-associated ILD while a positive test for anti-Jo-1 antibody indicated better prognosis. However, given the weak evidence they should be interpreted with caution.
Trial registration number CRD42016036999.
- idiopathic inflammatory myopathy
- interstitial lung disease
- systematic review
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Contributors HK planned the entire research project and analysed the data. He also summarised the result and wrote the manuscript. HK has full access to the data and takes responsibility for its integrity as well as the accuracy of the analysis. OMP contributed to the design of the research project and conducted the literature search and data extraction. He was also involved in revising the manuscript. SI contributed to the design of the research project, in particular, selecting the appropriate sample population. TS contributed to the planning of statistical analysis, in particular, determining the appropriate statistical methods to report summary effects and data synthesis. All researchers provided thoughts and opinions to compile a draft paper with revisions and then approved the final version of the manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement The data set used and/or analysed for this review will be available from the corresponding author on a reasonable request and may become open to the public through a digital repository (such as Dryad) after the final result is published in a journal.
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