Prevalence and incidence of systemic sclerosis: A systematic review and meta-analysis

Objective: Systemic sclerosis (SSc) is a rare debilitating autoimmune disease of the connective tissue. This study aimed to assess the recent prevalence and incidence of SSc across the world. Methods: Using a systematic search strategy, PubMed/MEDLINE and EMBASE were searched to identify relevant studies published between 2006 and 2016. Two reviewers independently evaluated studies for inclusion based on inclusion/exclusion criteria and performed data extraction. The review was conducted and reported following the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) statement. The pooled prevalence of SSc was calculated by meta-analysis using a random-effects model. Results: There were 1364 references retrieved using the initial searching strategy, and 20 epidemiological publications were selected for data extraction. The identified studies reported prevalence ranging from 3.8 per 100 000 in Taiwan to 50 per 100 000 in the USA. The prevalence was 23 per 100 000 (95% CI: 16-29 per 100 000; 18 studies) in a pooled sample of 11 574 individuals. Incidence rate of SSc ranges from 0.77 per 100 000 person-years in the Netherlands to 5.6 per 100 000 person-years in the USA. SSc predominates in females with higher prevalence and incidence rates. It is important to note that different methodologies were used to derive these numbers so comparisons were made with caution. Conclusion: This review provides an assessment of the current estimates of disease prevalence and incidence of SSc. The epidemiological burdens of SSc vary among different regions of the world. The epidemiological data need to be interpreted with caution considering the methodological differences in deriving these estimates.