Epidemiology of systemic sclerosis and systemic sclerosis-associated interstitial lung disease

Background: Interstitial lung disease (ILD) is one of the leading causes of mortality in patients with systemic sclerosis (SSc). To further understand this patient population, we present the first systematic review on the epidemiology of SSc and SSc-associated ILD (SSc-ILD). Methods: Bibliographic databases and web sources were searched for studies including patients with SSc and SSc-ILD in Europe and North America (United States and Canada). The systematic review was limited to publications in English, German, French, Spanish, Italian, and Portuguese, published between January 1, 2000 and February 29, 2016. For all publications included in the review, the methodologic quality was assessed. For each dimension and region, data availability in terms of quantity and consistency of reported findings was evaluated. Results: Fifty publications reporting epidemiologic data (prevalence, incidence, demographic profile, and survival and mortality) were included; 39 included patients with SSc and 16 included patients with SSc-ILD. The reported prevalence of SSc was 7.2-33.9 and 13.5-44.3 per 100,000 individuals in Europe and North America, respectively. Annual incidence estimates were 0.6-2.3 and 1.4-5.6 per 100,000 individuals in Europe and North America, respectively. Associated ILD was present in ~35% of the patients in Europe and ~52% of the patients in North America. In Europe, a study estimated the prevalence and annual incidence of SSc-ILD at 1.7-4.2 and 0.1-0.4 per 100,000 individuals, respectively. In both Europe and North America, SSc-ILD was diagnosed at a slightly older age than SSc, with both presentations of the disease affecting 2-3 times more women than men. Ten-year survival in patients with SSc was reported at 65-73% in Europe and 54-82% in North America, with cardiorespiratory manifestations (including ILD) associated with poor prognosis. Conclusion: This systematic review confirms that SSc and SSc-ILD are rare, with geographic variation in prevalence and incidence.