Physical urticaria: Review on classification,triggers and management with special focus on prevalence including a meta-analysis

Background. Physical urticaria (PU) is a subset of chronic urticaria (CU) induced by physical stimuli. To date, there is no consensus in the literature on the prevalence of PU among patients with CU. Objectives. Our objective was to review the clinical presentation, diagnosis and management of PU and to estimate the prevalence of PU in CU patients. Methods. We performed a narrative review of PU and conducted a systemic review and meta-analysis to determine the pooled estimates of the prevalence of PU among patients with CU in the literature up to September 2014. We searched four databases (PubMed, Ovid MEDLINE and Web of Science) of published work for which full text was available in English or French. Studies were eligible if they measured the prevalence of PU in adults or children with CU worldwide and ineligible if CU cases were not differentiated from total urticaria cases. Meta-analysis was conducted using Stata, version 12.0 (StataCorp, College Station, TX). In addition, the quality and validity of the articles included in the meta-analysis was assessed. Results. Ten studies were included in our meta-analysis. Sample sizes ranged from 202 to 4157 patients. The pooled prevalence estimate of PU including and excluding cholinergic forms among all cases of CU were 13.1% (95% CI: 12.5, 13.6) and 14.9% (95% CI: 14.3, 15.7), respectively. Conclusion. Our results must be viewed with circumspection because of the small number of eligible articles and heterogeneity among studies. Even so, the results suggest that PU is an important subset of CU and that physicians should be aware of this important condition in order to manage patients appropriately.