Polyautoimmunity and familial autoimmunity in systemic sclerosis.
Level 4 - case-series / case-control
Cross-sectional observational study
PubMed 18644698 · doi:10.1016/j.jaut.2008.05.002
What was done
Researchers conducted a cross-sectional study of 719 patients with systemic sclerosis (SSc) recruited from two convenience samples in Canada and Colombia. They assessed the prevalence of additional co-occurring autoimmune diseases in the patients (polyautoimmunity) and among their first-degree relatives (familial autoimmunity), and compared rates between diffuse and limited SSc subsets.
What was found
Of 719 patients, 273 (38%) had at least one other autoimmune disease (366 total co-occurring conditions reported). The most common were autoimmune thyroid disease (38%), rheumatoid arthritis (21%), Sjögren's syndrome (18%), and primary biliary cirrhosis (4%). Familial autoimmunity was identified in 260 patients (36%), predominantly rheumatoid arthritis (18%) and autoimmune thyroid disease (9%) in first-degree relatives. Having at least one first-degree relative with an autoimmune disease was a significant predictor of polyautoimmunity in the patient. Rates of polyautoimmunity and familial autoimmunity did not differ significantly between diffuse and limited SSc subtypes.
Why it matters
This study demonstrates substantial co-occurrence and familial clustering of diverse autoimmune disorders in systemic sclerosis, supporting the hypothesis of shared genetic susceptibility variants acting across different autoimmune phenotypes.
Limits
The study used convenience sampling rather than a population-based cohort and lacked healthy control comparators. Data relied on patient history without independent verification of relatives' diagnoses reported in the abstract. Quantitative risk estimates, such as odds ratios and confidence intervals for the predictive relationship, were not provided in the abstract.
Cited by
- supports Having one diagnosed autoimmune condition confers approximately a 30% chance of developing another autoimmune condition.