Prevalence of allergic rhinitis, atopic dermatitis, and wheezing at 15 and 22 years of age: the 1993 Pelotas (Brazil) Birth Cohort Study.

Objectives: To estimate the prevalence of allergic rhinitis (AR), atopic dermatitis (AD), and wheezing, and to describe their patterns of co-occurrence according to different characteristics in adolescence and early adulthood.

Methods: Cross-sectional analyses from the 15-year and 22-year follow-ups of the 1993 Pelotas (Brazil) Birth Cohort. The outcomes were assessed based on self-reported data, and the patterns of co-occurrence were determined using cluster analysis. The sample was described using absolute and relative frequencies according to the independent variables. Venn diagrams were generated to visualize the co-occurrence of AR, AD, and wheezing.

Results: Data on AR, AD, and wheezing were available for 4,286 participants at 15 years and 3,789 at 22 years. At 15 years, AR was reported by 20.9% of participants, AD by 25.2%, and wheezing by 33.4%. Meanwhile, at 22 years, AR was reported by 24.6%, AD by 14.2%, and wheezing by 30.7%. Notably, the overlap between AR and wheezing was greater than that of the other conditions (6.9% at 15 years and 8.3% at 22 years). Participants with lower maternal education and lower income were more likely to report having "no health condition". At 15 years, White individuals most frequently reported "three conditions" (4.1%; p<0.001), whereas at 22 years, they primarily reported "two conditions" (15.6%; p<0.001). The co-occurrence of all three health conditions was found to be greater than expected, with an observed rate 2.1 times higher (95% CI 1.4 - 3.0) at 22 years.

Conclusions: This study highlights the social gradient in the diagnosis and reporting of co-occurrence of AR, AD, and wheezing.