Document Type : Original Article



Background: Psoriasis is a chronic autoimmune skin disorder with relapsing erythematous scaling plaques and joint or nail involvement. A greater occurrence of other autoimmune diseases has been reported in these patients. Additionally, their family members are more likely to be diagnosed with psoriasis. The aimof this study is to assess the prevalence of certain autoimmune diseases in first degree relatives of patients with psoriasis compared with a control group.
Methods: In this cross-sectional study we used a questionnaire to compare the frequency of type 1 diabetes, autoimmune thyroid disease, vitiligo, lupus erythematosus, multiple sclerosis, ulcerative colitis, Crohn’s disease, and rheumatoid arthritis in first degree relatives of 109 pathologically confirmed psoriasiscases with the first degree relatives of 109 age-sex matched controls. R programming language (version 3.3.1 for Windows) and the rattle graphical user interface (GUI) package were applied for statistical analysis. A P-value?0.05 was considered to be statistically significant.
Results: We compared 955 first degree relatives of psoriatic patients with 934 family members of the controls. There was significantly greater total autoimmune diseases [odds ratio (OR): 2.74, 95% confidence interval (CI): 1.95-3.87, P<0.001), particularly psoriasis (OR: 38.66, 95% CI: 5.3-282.19, P<.0001), in first degree relatives of psoriatic patients compared to family members of the control group. Regardless of gender, autoimmune thyroid disease was more prevalent among first degree relatives of psoriatic patients (OR: 2.81, 95% CI: 1.36-5.83, P=.0066). No statistically significant difference was found regarding type 1 diabetes, rheumatoid arthritis, multiple sclerosis, vitiligo, Crohn’s disease, and ulcerative colitis.
Conclusion: First degree relatives of patients with psoriasis had significantly higher autoimmune diseases. This finding was particularly noticed for psoriasis and autoimmune thyroid disease.