Quality in epidemiological surveillance of contact allergy

The reporting of scientific results (in the field of contact dermatitis/allergy) should include a description of the methods used, including, but not limited to, standardized patch testing. Several aspects always need to be reported, such as duration of exposure, reading times, vehicle, and concentration of allergens. However, concerning other aspects, explicit compliance with international patch testing guidelines, notably the European Society of Contact Dermatitis guideline, which covers all relevant general aspects, is deemed to be a sufficient description of methods, supplemented by study-specific information, including partial non-compliance with the guideline, as indicated. Besides technical aspects, the quality of reporting of scientific results has several other dimensions, including epidemiological and biostatistical aspects discussed in this article. Prospectively, when a study is planned, performed, and reported, issues such as selection of patients and sample size and their impact on power and precision, the role of misclassification and potential conflicts of interests need to be addressed and discussed, respectively. Retrospectively, when a study is read and analysed, all relevant aspects of quality should be considered when the weight of evidence that a study publication provides is evaluated. Employing rigid 'quality criteria' may have the detrimental effect of relevant, if slightly imperfect, evidence being deliberately excluded.