ORIGINAL ARTICLE Association between atopic dermatitis and contact sensitization: A systematic review and meta-analysis Carsten R. Hamann, MD, a Dathan Hamann, MD, b Alexander Egeberg, MD, PhD, a Jeanne D. Johansen, MD, PhD, a,c Jonathan Silverberg, MD, PhD, MPH, d and Jacob P. Thyssen, MD, PhD a,c Hellerup, Denmark; Columbus, Ohio; and Chicago, Illinois Background: It is unclear whether patients with atopic dermatitis (AD) have an altered prevalence or risk for contact sensitization. Increased exposure to chemicals in topical products together with impaired skin barrier function suggest a higher risk, whereas the immune profile suggests a lower risk. Objective: To perform a systematic review and meta-analysis of the association between AD and contact sensitization. Methods: The PubMed/Medline, Embase, and Cochrane databases were searched for articles that reported on contact sensitization in individuals with and without AD. Results: The literature search yielded 10,083 citations; 417 were selected based on title and abstract screening and 74 met inclusion criteria. In a pooled analysis, no significant difference in contact sensitization between AD and controls was evident (random effects model odds ratio [OR] = 0.891; 95% confidence interval [CI] = 0.771-1.03). There was a positive correlation in studies that compared AD patients with individuals from the general population (OR 1.50, 95% CI 1.23-1.93) but an inverse association when comparing with referred populations (OR 0.753, 95% CI 0.63-0.90). Limitations: Included studies used different tools to diagnose AD and did not always provide information on current or past disease. Patch test allergens varied between studies. Conclusion: No overall relationship between AD and contact sensitization was found. We recommend that clinicians consider patch testing AD patients when allergic contact dermatitis is suspected. ( J Am Acad Dermatol http://dx.doi.org/10.1016/j.jaad.2017.02.001.) Key words: allergic contact dermatitis; atopic dermatitis; atopic risk factors; atopy; chromium; contact allergy; contact sensitization; eczema. From the Department of Dermatology and Allergy, Herlev and Gentofte Hospital, University of Copenhagen, Hellerup a ; Department of Internal Medicine, Division of Dermatology, Ohio State University, Columbus b ; National Allergy Research Centre, Department of Dermatology and Allergy, Herlev and Gentofte Hospital, University of Copenhagen, Hellerup c ; and the Departments of Dermatology, Preventive Medicine, and Medical Social Sciences, Feinberg School of Medicine at Northwestern University, Chicago. d Funding sources: None. Conflicts of interest: Drs C. R. Hamann and D. Hamann are first degree relatives of Curtis Hamann, owner of SmartPractice, a producer of contact allergy diagnostic testing materials. Dr Egeberg has received research funding from Pfizer and Eli Lilly, and honoraria for consulting and speaking for Pfizer, Eli Lilly, Novartis, Galderma, and Janssen Pharmaceuticals. Drs Johansen and Silverberg have no conflicts of interest. Dr Thyssen is supported by an unrestricted grant from the Lundbeck Foundation and has attended advisory board meetings for Roche and Sanofi-Genzyme. Preliminary data from this study was presented at the European Society of Contact Dermatitis, Manchester, England, September 16, 2016. Accepted for publication February 1, 2017. Reprints not available from the authors. Correspondence to: Carsten R. Hamann, MD, Herlev and Gentofte Hospital, Department of Dermatology and Allergy, Kildegaar- dsvej 28, 2900 Hellerup, Denmark. E-mail: hamann511@gmail. com. Published online April 6, 2017. 0190-9622/$36.00 Ó 2017 by the American Academy of Dermatology, Inc. http://dx.doi.org/10.1016/j.jaad.2017.02.001 1