The Value of Measuring Impact Alongside Symptoms in Children and Adolescents: A Longitudinal Assessment in a Community Sample

The impact that psychiatric symptoms have on the lives of young people is central to clinical practice and classification. However, there is relatively little research on impact and its association with symptoms. This paper examines how well impact can be measured and how it relates to psychiatric outcomes. On four separate occasions over 3 years, symptoms and impact were assessed in a UK epidemiological sample (n = 4,479; 51.5 % boys) using the Strengths and Difficulties Questionnaire (SDQ) as reported by parents, youths and teachers. Disorders were ascertained using the Development and Well-Being Assessment. An impact scale made of items about distress and impairment demonstrated considerable internal consistency, cross-informant correlations, and longitudinal stability by all reporting sources. Impact at baseline was a strong predictor of psychiatric disorder 3 years later after accounting for psychiatric disorders and symptoms measured at baseline: odds ratio OR = 2.10, 95 % Confidence Interval (CI) [1.50, 2.94] according to parent-rated impact and OR = 1.71, CI [1.08, 2.72] according to teacher-rated impact. Changes in impact over time were predicted, but not fully accounted for, by symptoms measured at baseline. Impact can be reliably and easily measured across time, and it may be clinically useful as an independent predictor of future symptoms and psychiatric disorders. More studies are needed to understand inter-individual variation in the impact caused by equivalent symptoms.