Fig. 2

a Presence of positive SPT to multiple or single aeroallergens in CSU populations in 16 studies. b Presence of positive SPT to multiple or single antigens in CSU populations in 3 studies, compared to healthy control groups with no history of atopy (p = 0.047). c Forest plot graphic assessing the relative risk of positive SPT to multiple or single aeroallergens. M–H, Mantel–Haenszel approach