Background: Early recognition of children's mental health problems calls for structured methods in front line services. The Strengths and Difficulties Questionnaire (SDQ) is a commonly used short questionnaire in screening child's mental difficulties.
Aim: To test the reliability and descriptive properties of the SDQ in a community sample of Finnish 4-9-year-old children (n = 4178).
Methods: Both parents, two teachers in day-care or a teacher at school completed the SDQ. To control for possible bias, public health nurses rated their concern about every child's mental health, including non-participants.
Results: The internal consistencies of the SDQ total score in all informants' reports were satisfactory to good. Agreement (Spearman rho) in total scores between parents was 0.65, between parent and teacher 0.43 and between two teachers in day-care 0.81. The stability in parent's reports over 12 weeks was good. The distributions of the informant-rated scores indicated significant and clinically important gender differences, and the 80th and 90th percentiles were generally below the international cut-off points. Public health nurses reported emotional or behavioural difficulties more commonly in non-participants (12%) than in participants (7%; p < 0.001).
Conclusions: The results supported earlier findings of good internal consistency, inter-rater and cross-informant agreements and test-retest of the method. However, the gender and age of the child, the number of informants and cultural differences in reporting styles affected the results and thus confirmed the need to re-evaluate the SDQ in the culture and population in question.