Fig. 3

a Presence of positive SPT to house dust mite antigen in CSU subjects in 18 studies. b Presence of positive SPT to house dust mite antigen 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 house dust mite antigen in CSU populations compared to healthy controls, M-H, Mantel–Haenszel approach