Screening for the attention deficit hyperactivity disorder phenotype using the strength and difficulties questionnaire

The strengths and difficulties questionnaire (SDQ) is a broad-band child mental health instrument, which has been reported
to be a good screener for the ADHD phenotype. Questionnaires containing the SDQ and the 18 SNAP-IV items corresponding to
the DSM-IV ADHD symptoms were completed by parents and teachers for 66% (N = 6,233) of all 7- to 9-year-olds in the city of Bergen, Norway, 2002. Screening properties of the five-item SDQ hyperactivity–inattention
subscale for the DSM-IV ADHD phenotype were examined. Using the DSM-IV ADHD phenotype based on both informants as the gold
standard (5.2% of the sample), the receiver operating characteristics (ROC) analyses demonstrated an area under the curve
of 0.91 (95% CI: 0.90–0.92) for parent and 0.95 (95% CI: 0.94–0.95) for teacher SDQ hyperactivity–inattention subscale ratings.
The SDQ hyperactivity–inattention predictive algorithm identified 74% of those with the ADHD combined subtype as possible
or probable cases, but only 22% of those with the inattentive subtype. The 5-item long SDQ hyperactivity–inattention subscale
is a shorter substitute for the 18-item ADHD symptom list. The SDQ predictive algorithm had an acceptable sensitivity for
the ADHD combined subtype, but low sensitivity for the ADHD inattentive and the ADHD hyperactive subtypes.