“…The reason for this observation may be attributed to the fact that more complex and resistant cases are usually referred to tertiary centers (Abd-Elmoneim et al, 2020;Baeyens, Roeyers, D'Haese, et al, 2007) Cohort studies allowed a more precise overview of age effects in concomitant enuresis and ADHD, and support findings of the cross sectional and case control designs (Baeyens, Roeyers, Van Erdeghem, et al, 2007;Cak et al, 2013;Mellon et al, 2013). In spite of that, further cohort studies are required in order to provide more robust evidence, since included studies present limitations such as small samples, heterogeneous control groups and low follow up time (Baeyens, Roeyers, Van Erdeghem, et al, 2007;Cak et al, 2013). One of the reviewed papers, in spite of being a population-based study, was probably not representative of the general population, since the sample included only children from a mainly white, middle class community, which may limit inferences to other populations (Mellon et al, 2013).…”