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

OBJECTIVES: The prevalence and outcome of mixed connective tissue disease-associated pulmonary arterial hypertension (MCTD-PAH) has not been well understood. 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 published 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 association between PAH and female gender or age. The percentage of deaths in MCTD patients due to PAH varied and reached up to 81.8%. CONCLUSIONS: This is the first systematic review and meta-analysis investigating the prevalence of PAH in patients with MCTD and it revealed an overall prevalence 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 revealed an increased mortality rate. We also determined the low impact of the age, gender, and interstitial lung disease on MCTD-PAH.