(because only one study derived the diagnosis based on ‘and rule’, but also on ‘or-rule’, we selected the rate associated with the latter); v) requirement or not of impairment for the diagnosis: yes or no. Although sex of the child is an important covariate that is well known to be associated with the prevalence rates of CD and ODD [55, 59–61], it was not included in the analyses due to the small number of eligible studies that presented rates of these disorders by sex and also presented confidence intervals (See Table 2).
