Abstract
<title>Abstract</title> <p> <italic> <bold>Background:</bold> </italic> The SDQ is a widely used instrument available in different languages and in both proxy-report and self-report versions. Population-based dual-informant SDQ data stratified by developmental stage, gender, and language are scarce in Italian populations. <italic> <bold>Methods:</bold> </italic> A large regional sample provided proxy- and self- reported SDQ scores for age groups ranging from 6 and 19 years. Data was compared with international reference norms. Age and gender effects were analyzed, and interrater correlations were used to investigate dual informant discrepancies. Language-related differences and differences between completed and not completed self-reports were analyzed. <italic> <bold>Results</bold> </italic> 5,745 parent-reports and 1,523 self-reports from adolescents were analyzed. Self-reported mean scores corresponded mainly to Italian norms from 2017. Largest proxy-reported effect sizes (0.13-0.15) between age groups were observed between the 6-10 year and 15–19-year age groups. Among younger boys, highest scores were observed for hyperactivity and conduct problems. For girls, the same pattern was detected for hyperactivity. Peer problems and emotional problems were detected mostly in 15–19-years old girls. Effect sizes between age groups for self-reported data were highest among boys for peer problems (0.103) and among girls for emotional problems (0.116) with higher rates in the group from 15-19. Highest effect sizes between genders (>0.2) were observed for emotional and hyperactivity problem scores with higher emotional scores for girls and higher hyperactivity scores for boys aged 11–14. Interrater correlation was moderate, with highest values for total scores (0.568-0.661) and lowest rates for conduct scores (0.450-0.548). Interrater correlations did not differ substantially across age groups. Proxy- reported data tended to score mental health issues lower compared with self-reported data among older adolescents. Language-related differences were observed for self-reported male emotional and hyperactivity and in female peer problem scores. <italic> <bold>Conclusions</bold> </italic> Post-pandemic Italian SDQ norms are needed for proxy- and self-reports. Females aged 15-19 years emerged as the most vulnerable subgroup, highlighting the need for targeted preventive interventions. Older adolescents reported greater difficulties relative to parental reports; thus, the dual-informant approach is important even for older adolescents. SDQ results appeared stable across languages in parent reports; however, further research is needed for self-reports. </p>