Epidemiology of Systemic Sclerosis

Incidence, Prevalence, Survival, Risk Factors, Malignancy, and Environmental Triggers

Jammie Barnes; Maureen D. Mayes

Disclosures

Curr Opin Rheumatol. 2012;24(2):165-170. 

In This Article

Survival

Survival in SSc has improved significantly compared with earlier published reports. In 2007, Steen and Medsger[25] reported the 10-year cumulative survival rate in their longitudinal Pittsburgh cohort. They reported an improvement in survival from 54% in the 1970s to 66% in the 1990s. The improvement in survival was attributed to improvement in diagnosis (lead time bias) and the implementation of effective therapy for scleroderma renal crisis. They found that pulmonary fibrosis and pulmonary arterial hypertension supplanted scleroderma renal crisis as the leading causes of death in SSc-related mortality ( Table 2 ).

Recently, the causes and risk factors for death in SSc were reported by the European League against Rheumatism (EULAR) Scleroderma Trials and Research (EUSTAR) database.[26••] The database included 5860 SSc patients who fulfilled the ACR 1980 classification criteria. Causes of death and comorbidity data were available from 234 of 284 fatalities. Using a multivariate Cox proportional hazards model to calculate predictors of mortality, they reported that 55% of deaths were directly related to SSc and 41% to non-SSc causes with the remaining 4% of cases considered nonclassifiable. Among the 284 deceased patients, 54.6% had diffuse cutaneous disease (dcSSc) and 40.5% had limited cutaneous disease (lcSSc). The median disease duration was 7.1 years for dcSSc and 15 years for lcSSc. 19% died of pulmonary fibrosis and 14% of pulmonary arterial hypertension. SSc-related myocardial disease death was 14% with most causes being related to arrhythmias. Renal causes of death only accounted for 4%, all of which were related to scleroderma renal crisis. Three percentage of patients died from gastrointestinal-related causes.

With respect to the non-SSc-related deaths, causes were as follows: infections (13%of all deaths), neoplasia (13%), and cardiovascular disease (12%). Patients with non-SSc-related deaths were then analyzed for SSc-related comorbidities. A significant number of patients who died from pneumonia also had presence of gastroesophageal reflux with or without documented aspiration. Of the fourteen patients who died from lung cancer, nine had concomitant pulmonary fibrosis. In this study, independent predictors of reduced survival included presence of proteinuria, pulmonary arterial hypertension, pulmonary restriction with a forced vital capacity of less than 80% predicted, presence of dyspnea greater than New York Heart Association Class II, higher age at onset of Raynaud's phenomenon, lower diffusion capacity for carbon monoxide, and a modified Rodman skin score greater than 10. This report reinforced the previous finding that pulmonary fibrosis and pulmonary arterial hypertension are the leading causes of SSc-related deaths and likely contribute to non-SSc-related deaths.

In addition, a population-based South Australian registry reported survival in 786 scleroderma patients using standardized mortality ratios compared with the general population.[27•] As expected, SSc patients had decreased survival compared with a standardized mortality ratio of 1.46 [95% confidence interval (CI) 1.28–1.69]. Factors that increased mortality in this study were older age of onset, male sex, scleroderma renal crisis, pulmonary fibrosis, pulmonary arterial hypertension, cancer, and antitopoisomerase and anti-U1 antibodies.

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