Mortality and its risk factors in critically ill patients with connective tissue diseases: A meta-analysis

Background: Systemic lupus erythematosus (SLE), primary Sjogren's syndrome (pSS), systemic sclerosis (SSc), idiopathic inflammatory myopathies (IIM) and rheumatoid arthritis (RA) are connective tissue diseases (CTD) whose complications can lead to management in the intensive care unit (ICU). Objectives: To estimate by meta-analysis ICU mortality rates for CTD. Methods: A systematic literature review was performed to identify articles studying critically ill CTD patients. A random-effects model was chosen for analysis. Pooled proportion mortality was calculated using aggregated-data meta-analysis with a random-effects model and assessment of heterogeneity with the I-2 statistic. Risk of bias was assessed using the quality assessment tool. Results: Of the 5694 individual publications, a sample of 31 independent cohorts was used for the meta-analysis totalling 5007 patients. The main cause for admission was sepsis (43%) followed by "flare-ups" (40%). The overall pooled proportion of mortality of CTD patients across all 31 studies was 33% (95%CI: 28-38%). In the IIM subgroup and that of SSc, mortality was 70% (95%CI: 46-86%) and 40% (95%CI: 25-47%), respectively. In the SLE subgroup, mortality was similar to the overall pooled mortality of 35% (95%CI: 29-42%). Subgroup mortality for RA and pSS patients was respectively 20% (95%CI: 11-33%) and 17% (95%CI: 6-41%); lower than the overall pooled mortality. Heterogeneity in each subgroup remained high. Conclusion: The overall pooled proportion of mortality of ICU patients with CTD was 33% (95%CI: 28-38%), with a high heterogeneity (I-2 = 89%). In the subgroup analysis, mortality was higher for patients with IIM and SSc.