A systematic review is the process of explicitly and rigorously collecting and summarizing all the best evidence available to answer a clearly defined clinical question, as reported by Rodríguez-Zuñiga et al. in their article in this issue. We should mention that while the terms systematic review and meta-analysis are sometimes used synonymously, the two are not the same: the former is the process defined above and the latter is a procedure that uses statistical analysis to combine the results of various studies.1 The review presented in this month's article,2 which was carried out in early 2016, is based on an earlier study carried out in 2013, with differences in the inclusion criteria, such as the language and place of publication.3 The aim of both reviews was to provide additional information on the relationship between psoriasis and metabolic syndrome, and both found the risk for metabolic syndrome to be higher in patients with psoriasis than in the general population. However, both studies are affected by certain limitations that make the task more difficult. The most difficult task was to clearly and precisely define the research question to be answered by the review process; this question is usually much clearer in other types of studies, such as clinical trials studying therapeutic interventions.4 Despite the limitations, this is a very interesting review that will help clinicians to manage the metabolic health of their patients with psoriasis and will contribute epidemiological data needed to quantify the scale of the problem.