Epidemiology
Systemic sclerosis is a rare disease with an incidence in adults between 2.6 and 20 to 28 per million per year.[12,13] The true incidence is underestimated since early features are frequently overlooked. The prevalence of SSc is 13 to 140 per million; even 290 per million in South Carolina.[12] In Canada 74.4 cases per 100,000 women and 13.3 cases per 100,000 men have been described.[14] The overall female/male ratio is around 3:1.[12] However, this ratio is larger in Great Britain (6:1) and in the United States (8:1).[15]
The standardized mortality ratio was estimated at 1.5 to 7.2 fold in an international meta-analysis.[16] About 50% of patients die or develop major internal organ complications within 3 years of diagnosis. Survival rates closely follow major organ involvement. Significant advances in treating renal disease, pulmonary hypertension (PHT), and esophageal involvement have increased the 10-year survival rates to around 80%.[17] Most patients die of cardiopulmonary or renal disease.
Out of 646 patients studied before angiotensin-converting enzyme (ACE) inhibitor treatment, none of the 24 patients with kidney disease at onset survived for 6 years, and the 1-year survival was only 25%.[19] Cancer mortality particularly of the lung is also increased.[12]
Lab Med. 2011;42(9):562-572. © 2011 American Society for Clinical Pathology
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