Global, regional, and national incidence and prevalence of systemic sclerosis

OBJECTIVES

To estimate the global and country-specific unbiased epidemiological data of SSc.

METHODS

Epidemiological studies were systematically searched in four databases. A Bayesian hierarchical linear mixed model was constructed to estimate epidemiological data.

RESULTS

82 studies were included and epidemiological data on SSc were missing for 83.9% of countries worldwide. The global SSc incidence and newly diagnosed population were estimated to be 8.64 per 100,000 person-years (1.78-23.57) and 0.67 million (0.14-1.84) people annually, respectively. Regarding prevalence, the global SSc prevalence and affected population were 18.87 per 100,000 persons (1.55-25.28) and 1.47 million (0.12-1.97) people, respectively. Relatively higher incidence and prevalence were observed in females, adults, and high-income level countries.

CONCLUSIONS

We provide a comprehensive synthesis of SSc epidemiology and fill data gaps in most countries. Especially in low- and middle-income countries, epidemiological studies of SSc are insufficient. Further large-scale and standardized reported epidemiological investigations of SSc are imperative.

A Narrative Review of Pathogenetic and Histopathologic Aspects, Epidemiology, Classification Systems, and Disease Outcome Measures in Systemic Sclerosis

Systemic sclerosis (SSc) is a rare systemic autoimmune disease, characterized by the presence of three main actors: vasculopathy, immune activation, and fibrosis. This pathologic process is then translated in a clinical picture with great variability among different patients in terms of type of organ involvement, disease severity and prognosis. This heterogeneity is a main feature of SSc, which, in addition to the presence of early phases of the disease characterized by mild symptoms, can explain the high difficulty in establishing classification criteria, and in defining patients' subsets and disease outcomes. The definition of disease outcomes is particularly relevant in the setting of clinical trials, where the aim is to provide reliable endpoints, able to measure the magnitude of the efficacy of a certain drug or intervention. For this reason, in the last years, increasing efforts have been done to design measures of disease activity, damage, severity, and response to treatment, often in the context of composite indexes. When considering disease outcomes, the experience of the patient represents a relevant and complementary aspect. The tools able to capture this experience, the patient-reported outcomes, have been increasingly used in the last years in clinical practice and in clinical trials, both as primary and secondary endpoints. This comprehensive narrative review on SSc will therefore cover pathogenetic and histopathologic aspects, epidemiology, classification systems, and disease outcome measures, in order to focus on issues that are relevant for clinical research and design of clinical trials.

Incidence and prevalence of systemic sclerosis globally: a comprehensive systematic review and meta-analysis

OBJECTIVES

We aimed to conduct a systematic review and meta-analysis on the incidence and prevalence of SSc covering the entire literature.

METHODS

This study followed the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement of 2009. We conducted a systematic search in MEDLINE, Web of Science and Embase to identify articles reporting incidence and/or prevalence of SSc. Two authors conducted the search, reviewed articles for inclusion and extracted relevant data. We used random-effects models to estimate the pooled prevalence and incidence of SSc and performed subgroup analyses by sex, case definition and region to investigate heterogeneity. We explored the association between calendar period and reported estimates using meta-regression.

RESULTS

Among 6983 unique records identified, we included 61 studies of prevalence and 39 studies of incidence in the systematic review. The overall pooled prevalence of SSc was 17.6 (95% CI 15.1, 20.5) per 100 000 and the overall pooled incidence rate of SSc was 1.4 (95% CI 1.1, 1.9) per 100 000 person-years. We observed significant regional variations in reported estimates; studies conducted in North America reported considerably higher estimates than other regions. The pooled incidence and prevalence in women were five times higher than in men. More recent studies reported higher estimates than older ones.

CONCLUSION

In this comprehensive review of the incidence and prevalence of SSc across the world, there was large heterogeneity among estimates, which should be taken into consideration when interpreting the results.

Incidence, prevalence and mortality of systemic sclerosis in Italy: a nationwide population-based study using administrative health data

To study incidence, prevalence and mortality of systemic sclerosis (SSc) in Italy, assessing epidemiological differences between men and women and in distinct age groups. We performed a nationwide population-based study using administrative health data from regional co-payment exemption registries. Patients entitled with SSc-specific co-payment exemption were included. Fourteen of the 20 Italian regions contributed data covering a population of over 45 million individuals. Crude annual incidence rate, annual prevalence, crude annual mortality rate and standardised mortality ratio (SMR) were calculated. In 2016, the overall crude incidence rate of SSc was 18.5 (95% CI 16.9-20.2) per million per year. Incidence rate was 31.0 (95% CI 28.1-34.1) per million in women, and 4.3 (95% CI 3.2-5.6) per million in men. Peak incidence was observed in the age range 55-69 years. Overall annual prevalence was 306.1 (95% CI 301.1-311.2) per million. Prevalence was 530.8 (95% CI 521.5-540.2) per million in women and 67.8 (95% CI 64.4-71.3) per million in men, with a female to male ratio of 7.8:1. Highest prevalence was observed in the range 70-84 years. Crude annual mortality rate was 27.9 (95% CI 24.9-31.1) per 1000 patients. Overall SMR in patients with SSc was 2.8 (95% CI 1.9-3.8). SMR was 3.8 (95% CI 2.9-5.1) in men and 2.6 (95% CI 1.8-3.6) in women. We provided updated estimates on epidemiology of SSc in Italy. Our findings on incidence, prevalence and mortality of SSc are consistent with previously published literature.