Psychometric properties of the preschool strengths and difficulties questionnaire (SDQ) in UK 1-to-2-year-olds

Early identification of emotional and behavioural difficulties in very young children is crucial for intervention and prevention. The Strengths and Difficulties Questionnaire (SDQ) is a widely used measure of child and adolescent mental health that is brief, cost-effective, and easy to administer. The aims of this study were to establish the validity and reliability of the preschool SDQ in UK 1-2-year-olds. This study investigated the psychometric properties of the Preschool SDQ in a large UK sample (N = 2040; female = 46.86%; male = 50.83%, sex not recorded = 2.30%) of infants and toddlers (1-2-year-olds). Analyses were performed at item-level (internal consistency, internal structure, measurement invariance) and scale-level (test–retest reliability, convergent validity). Similar to previous research, confirmatory factor analysis supported a slightly modified five-factor model, including the addition of a positive construal method factor, resulting in satisfactory data fit and a moderately good fitting model. Internal consistency (Cronbach’s alpha) for the SDQ total difficulties score was satisfactory, and higher for externalising over internalising problems. Moderate to strong correlations indicated good test–retest reliability, and moderate correlations indicated convergent validity between the SDQ and Child Behavior Checklist (CBCL), but associations were weaker than those found in studies with older children. Conclusions: The SDQ demonstrated satisfactory psychometric properties, suggesting that it may be a useful tool for the detection of early mental health difficulties, particularly externalising symptoms, even in very young toddlers. Further research is needed to validate the SDQ in younger populations and to establish cut-off scores for clinical interpretation. The implications of these findings are discussed. (Table presented.)