Study quality and bias assessment
Concerning the prevalence of rhinitis in patients with urticaria, 8 studies were of good quality,15,21,26-28,37-39yielding a pooled prevalence of 17.0% (95% CI, 10.4%–23.5%). The corresponding estimate for studies categorized as being of fair or poor quality was 17.8% (95% CI, 12.3%–23.3%) based on data from 9 studies.20,29-36 Regarding the prevalence of urticaria in patients with rhinitis, 23 studies14,17-19,22,40-42,45-47,50,52,53,55-58,61-64,66were of good quality, with a prevalence of 38.3%(95% CI, 29.1%–47.6%), while 16 studies6,11-13,16,23,43,44,48,49,51,54,59,60,65,67were considered of fair or poor quality, with a prevalence of 19.9% (95% CI, 16.1%–23.6%).
Moreover, a large heterogeneity was observed between the included studies. The respective I2 was 91% and 99.3% from the studies included for statistics on the prevalence of urticaria in patients with rhinitis and rhinitis in patients with urticaria. Correspondingly, according to the studies on the prevalence of urticaria in patients with rhinitis, the Egger bias test indicated a significant risk of publication bias for the aforementioned analyses (p=0.001). However, based on the studies on the prevalence of rhinitis in patients with urticaria, a low risk of publication bias was observed (p=0.558).