Systemic sclerosis prevalence and comorbidities in the US, 2001-2002

Area of Science:

• Rheumatology
• Epidemiology
• Public Health

Background:

• Systemic sclerosis (SSc) is a rare autoimmune disease with limited population-based prevalence and comorbidity data in the US.
• Understanding SSc's impact on overall health and its association with other conditions is crucial for patient care and resource allocation.

Purpose of the Study:

• To determine the prevalence of SSc in the US population.
• To investigate the patterns of autoimmune and other comorbidities in SSc patients compared to controls.

Main Methods:

• Utilized two large US claims databases (IMS Health and MarketScan) from 2001-2002.
• Identified SSc cases and comorbidities using ICD-9 codes; matched controls 4:1 based on demographics and insurance history.
• Calculated prevalence and relative risks (RR) for comorbidities, employing sensitivity analyses to validate findings.

Main Results:

• SSc prevalence was estimated at 0.05% in the US population.
• SSc patients exhibited significantly higher risks for multiple sclerosis (RR 3.2-6.6) and inflammatory bowel disease (RR 2.1-2.2).
• SSc patients demonstrated a substantially higher chronic disease burden, including increased risks for cardiovascular, renal, liver, and neuropsychiatric diseases.

Conclusions:

• This study provides a population-based prevalence estimate for SSc in the US.
• SSc patients face an elevated risk of other autoimmune conditions and a greater overall chronic disease burden.
• Limitations include potential inaccuracies in ICD-9 coding for SSc identification and database-specific biases.