Supplementary Material for: Epidemiology and Comorbidities of Psoriasis among Israeli Adolescents: A Large Cross-Sectional Study

Background and Aims: Although psoriasis can develop at any age, the data regarding its characteristics in adolescents are sparse. This study was designed to determine the psoriasis prevalence and its associations with the body mass index (BMI), lipid profile, and comorbidities in adolescents. Methods: This was a nationwide population-based cross-sectional retrospective study of adolescents (16–18 years old) evaluated for military service between January 1999 and January 2014. Results: Our database included 887,765 adolescents (57.1% males), of whom 3,112 (0.35%) were diagnosed with psoriasis. During the 15-year study period, the psoriasis prevalence increased by 1.4-fold, from 0.3 to 0.42% (1.25-fold for the males and 1.63-fold for the females). Certain comorbidities, such as contact dermatitis, hyperhidrosis, and arthritis, were significantly associated with psoriasis (odds ratios [ORs] of 2.26, 1.51, and 5.3, respectively). The adolescents with psoriasis had significantly elevated BMI and triglyceride values. We found increased ORs of 1.34 (95% confidence interval [CI] = 1.25–1.56) and 1.56 (95% CI = 1.32–1.83) for the overweight and obese adolescents, respectively, while a lower BMI (<20) had an opposite effect with psoriasis (OR = 0.8). Conclusions: Based on our results, the psoriasis prevalence in Israeli adolescents is rising. Dermatological comorbidities and an increased BMI were associated with psoriasis in these adolescents. A better understanding of the distinctive epidemiological characteristics of juvenile psoriasis may allow for the early detection of comorbidities and improve its management.