Incidence and Prevalence of Systemic Sclerosis
Previously reported incidence and prevalence estimates vary greatly according to geographic location and methods of case ascertainment. Classification criteria were not developed until 1980 when the American Rheumatism Association (now the American College of Rheumatology, ACR) proposed criteria to distinguish SSc from other connective tissue diseases. Table 1 [4–20] summarizes the reported incidence and prevalence studies. This table excludes 'scleroderma spectrum disorders'.
Monaco et al. [21•] reported a retrospective review of Italian-origin patients (age ≥16 years) with a diagnosis of SSc criteria based on the ACR 1980 classification criteria and the revised LeRoy and Medsger 2001 criteria. Patients were identified from outpatient clinics in the Ferrara district (study area of 346 000 population) from 1999 through 2007. The authors found 118 patients who met the LeRoy–Medsger criteria and 88 patients who met the stricter 1980 ACR criteria. Using the LeRoy–Medsger criteria, the annual incidence rate and prevalence estimate are, respectively, 43 and 341 cases per million. However, fewer met ACR classification criteria, leading to incidence and prevalence estimates of 32 and 254 cases per million, respectively. They further defined the cases into SSc subsets according to the LeRoy and Medsger system. They had 20 limited SSc and 76 limited cutaneous SSc and 22 diffuse cutaneous SSc. They noted a female predominance with a female to male ratio of 9.7 : 1.
Another article by Rosa et al. [22•] examined SSc incidence and prevalence in the city of Buenos Aires, Argentina. They reviewed members of a prepaid health maintenance program between 1999 and 2004 with a total of 98 642 persons. The population was largely white and of European descent with only 3% from other ethnicities. They also used the 1980ACRclassificationcriteria and/or the LeRoy and Medsger criteria to define cases. They reported an annual incidence of 21.1 cases per million and a prevalence of 296 cases per million. They also further divided the cases into diffuse and limited SSc. The incidence and prevalence for diffuse SSc were 6.1 and 57 cases per million, respectively, and for limited SSc were 15.2 and 240 cases per million. This group was the first to report the SSc incidence rate and prevalence estimate in Latin America. Their figures are similar to those reported for the US population as well as for Spain and Australia. They also found a comparable female to male ratio.
In Taiwan, Kuo et al. [23•] reviewed cases from the catastrophic illness registry of the Taiwan National Health Insurance Research Dataset and the National Death Registry of Taiwan to estimate the incidence, prevalence and mortality of SSc. A total of 1479 persons with SSc were identified in this study. The annual incidence rate was 10.9 cases per million and the prevalence was 56.3 cases per million.
In north India, Minz et al. [24•] reported the prevalence of antinuclear antibody (ANA) positive autoimmune disorders. They reviewed ANA-positive files from 1996 to 2006 and did a retrospective analysis of the cases, including both adults and children. They reported a prevalence of SSc at 120 cases per million. They included another subgroup of cases as CTD overlap as 70 cases per million and Raynaud's disease as 50 cases per million. It is difficult to interpret these prevalence estimates, as the authors did not specify the classification criteria they used to diagnose SSc.
Curr Opin Rheumatol. 2012;24(2):165-170. © 2012 Lippincott Williams & Wilkins