We found that 1 in 4 patients with psoriasis have PsA. With the growing recognition of the Classification Criteria for Psoriatic Arthritis, more homogenous and comparable prevalence estimates are expected to be reported.

Objectives: To provide an updated estimate of the prevalence of contact allergy in the general population based on data from our previous review combined with new data from an updated search for relevant studies published between 2007 and 2017. Methods: Two authors independently searched PubMed for studies reporting on the prevalence of contact allergy in samples of the general population. Proportion meta-analyses were performed to calculate the pooled prevalence estimates of contact allergy. Results: A total of 28 studies were included in the analysis, covering 20 107 patch tested individuals from the general population. Overall, the pooled prevalence of contact allergy was 20.1% (95% confidence interval [CI]: 16.8%-23.7%). In children and adolescents (<18 years), the prevalence was 16.5% (95%CI: 13.6%-19.7%). The prevalence was significantly higher in women (27.9% [95%CI: 21.7%-34.5%]) than in men (13.2% [95%CI: 9.3%-17.6%]). The most common allergen was nickel (11.4% [95%CI: 9.4%-13.5%]), followed by fragrance mix I (3.5% [95%CI: 2.1%-5.4%]), cobalt (2.7% [95%CI: 2.1%-3.4%]), Myroxylon pereirae (1.8% [95%CI: 1.0%-2.7%]), chromium (1.8% [95%CI: 1.3%-2.6%]), p-phenylenediamine (1.5% [95%CI: 1.0%-2.1%]), methylchloroisothiazolinone/methylisothiazolinone (1.5% [95%CI: 0.8%-2.5%]), and colophonium (1.3% [95%CI: 1.0%-1.6%]).Conclusions: This meta-analysis confirmed that at least 20% of the general population are contact-allergic to common environmental allergens. It highlights the need for more effective preventive strategies for common allergens in consumer goods, cosmetics, and the workplace.contact allergy, epidemiology, general population, hapten, meta-analysis, prevalence and Janssen Pharmaceuticals. J. P. Thyssen is supported by an unrestricted grant from the Lundbeck Foundation. ORCID Farzad Alinaghi

Background and Aims Epidemiological studies have established an association between psoriasis and inflammatory bowel disease [IBD], i.e. ulcerative colitis [UC] and Crohn’s disease [CD], but results are inconsistent. The aim of this study was therefore to quantify the prevalences and association between IBD and psoriasis. Methods PubMed, Web of Science, and EMBASE were searched from database inception through April 2018 for studies reporting data on psoriasis among patients with IBD and vice versa. Meta-analysis was performed to estimate, respectively, the prevalences and association between IBD and psoriasis. Data extraction was according to the PRISMA guideline, and quality assessment was made using the Newcastle-Ottawa Scale. The main outcomes were the proportion of psoriasis patients with IBD and vice versa, as well as the association (odds ratio [OR]) of IBD in psoriasis and psoriasis in IBD, respectively. Results Based on quantitative analysis of 93 studies, the prevalence of psoriasis in CD and in UC was 3.6% (95% confidence interval [CI] 3.1%–4.6%) and 2.8% [95% CI 2.0%–3.8%] respectively. The prevalence of CD and UC was 0.7% [95% CI 0.2%–1.3%] and 0.5% [95% CI 0.3%–0.8%], respectively, among patients with psoriasis. Presence of CD or UC was significantly associated with psoriasis, with OR 2.0 [95% CI 1.4–2.9] and OR 1.5 [95% CI 1.2–2.0], respectively. Presence of psoriasis was significantly associated with CD: OR 2.2 [95% CI 1.6–3.1] and with UC: OR 1.6 [95% CI 1.3–2.0]. Conclusions We found significant bidirectional associations between psoriasis and IBD, warranting increased awareness among clinicians in the diagnostic process, especially in children and adolescents with IBD. Last, this study showed an increased frequency of paradoxical psoriasis in patients treated with biologics.