Aim To examine whether the results at 4 years of age of the developmental questionnaire QS4-G can predict the outcome of cognitive, neuropsychological and academic abilities 4-6 years later. The QS4-G is a validated parental questionnaire designed for the screening and surveillance of the neuropsychological and behavioural developmental status of 4-year-olds (93 questions). Methods Longitudinal prospective study on a subsample of the QS4-G validation original sample was conducted. According to previous results, the sample was divided into two groups: 'at risk' and 'not at risk'. Sensitivity, specificity, accuracy and likelihood ratios were assessed and referred to outcomes. Results Thirty-five children were classified as 'not at risk' and 16 as 'at risk'. There were significant associations between past QS4-G score and cognitive, neuropsychological and academic abilities 4-6 years later. With the same cut-off identified at the first cross-sectional study, sensitivity and specificity for difficulties in cognitive development were 90% and 83% while in the neuropsychological abilities 62% and 90%, respectively. A lower predictive validity was found for difficulties in academic abilities (sensitivity 43%, specificity 86%). QS4-G specific area scores showed significant correlations with related academic tests at follow-up (rho range: 0.404-0.565, P < 0.005). Conclusions QS4-G shows good predictive validity for cognitive development and neuropsychological abilities. The risk of false negatives for academic abilities can be reduced by analysing the specific area results of QS4-G, which show good correlations with related tests at follow-up.
