The prevalence of pulmonary arterial hypertension in patients with mixed connective tissue disease: a systematic review and meta-analysis

Objective. The prevalence and outcome of mixed connective tissue disease-asso-ciated pulmonary arterial hypertension (MCTD-PAH) has not been well under-stood. Our aim was to review the current knowledge on the prevalence, severity, and mortality of MCTD-PAH. We also aimed to examine the prevalence trend of MCTD-PAH over the years. Methods. PubMed/Medline, Embase, Scopus and Web of Science electronic databases were searched for the pub-lished randomised controlled clinical trials (RCTs) and observational/original studies on PAH in patients with MCTD from January 1972 to December 2020. Results. The results were pooled using random-effects meta-analysis based on DerSimonian and Laird method. A total of 983 patients from eight studies were included in the meta-analysis (K=8, n=983). Pooled prevalence of PAH in MCTD patients was 12.53% [95% CI 8.30-18.48%] with significant level statistical heterogeneity (tau2=0.30, tau=0.55, i2 83.3%, H=2.13 Q(df,7) =31.90, p=0.001). There was no asso-ciation between PAH and female gen-der or age. The percentage of deaths in MCTD patients due to PAH varied and reached up to 81.8%. Conclusion. This is the first systematic review and meta-analysis investigating the prevalence of PAH in patients with MCTD and it revealed an overall preva-lence of PAH in patients with MCTD of 12.53%. Our results showed trends of reduced prevalence of MCTD-PAH over last four decade, reconfirmed the lower prevalence rate in recent studies, but re-vealed an increased mortality rate. We also determined the low impact of the age, gender, and interstitial lung dis-ease on MCTD-PAH.