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

Risk Factors

Previously reported risk factors for the development of SSc include sex, race, age, family history, birth order, and genetic factors. As noted above in recent incidence and prevalence data, women considerably outnumber men.

In terms of race/ethnicity, African-Americans have been reported to have earlier onset and more severe disease. Nashid et al. [32•] collected data from three randomized clinical treatment trials to evaluate sex and ethnicity differences. Their report included 495 patients of which 81.4% were women, 71.1% were non-Hispanic Caucasian, 16% were African-American, 9.5% were Hispanic, and 3.4% belonged to another category (Asian and unknown). On average, men had higher serumcreatinine, hematocrit, and creatine phosphokinase (CPK). However, functional quality of life as assessed by the Health Assessment Questionnaire with Disability Index (HAQ-DI) was lower (better) in men than in women. On average, Caucasian patients were older than African-American and Hispanic patients. African-American patients had higher CPK levels and worse pulmonary function than the other two groups. Hispanic patients had more tender joints compared with the other groups. The course of skin disease and percentage predicted forced vital capacity did not differ between sex and ethnicities. Another study by Manno et al. [33•] evaluated the age of onset and the severity of disease. The group hypothesized that later-age onset SSc would have a different risk for specific organ manifestations. They evaluated 2300 SSc patients from 1990 to 2009 from the Johns Hopkins Scleroderma Center, defining SSc based on the LeRoy–Medsger criteria. Of the 2300 patients, 216 had disease onset at at least 65 years. A higher proportion of these lateonset patients had anticentromere antibodies than did their younger counterparts. The risk of pulmonary hypertension, muscle weakness, renal impairment, and cardiac disease was greater among the late-onset patients. However, the risk of digital ischemia was reduced in this group. There was no difference in the prevalence of scleroderma renal crisis between the groups.

Genetic risk factors have been studied by several groups. In the past year, Nguyen et al.[34] reported HLA markers that have a predictive role in scleroderma renal crisis. They included 1519 SSc patients, 90 of whom had scleroderma renal crisis. These authors found that HLA-DRB1•0407 and HLADRB1•1304 are risk factors for renal crisis independently of clinical variables. Similarly to previous studies, they confirmed that diffuse cutaneous involvement and anti-RNA polymerase III antibodies were also risk factors for scleroderma renal crisis.

A large genome-wide association study (GWAS) by Gorlova et al. [35•] identified genetic components contributing to the different clinical subphenotypes of SSc. Analyzing a total of 2296 SSc cases and 5171 healthy controls and confirmed in an independent group of 3175 SSc cases and 4971 controls, they found that disease susceptibility as well as disease severity are influenced by genetic factors including both the HLA/MHC region as well as non-MHC loci.

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