Quantitative and subjective behavioural aspects in the assessment of attention-deficit hyperactivity disorder (ADHD) in adults.

BACKGROUND: Self-rating scales and cognitive tests are instruments used in the assessment of attention-deficit hyperactivity disorder (ADHD). However, few studies have examined the differential validity of these kinds of instruments in psychiatric samples.

AIMS: To examine the discriminative validity of two self-report scales (ADHD Self-Report Scale [ASRS v.1.1], Current Symptom Scale [CSS]) and a continuous performance test with measures of motor activity (QBTest Plus).

METHODS: The interrelation between the instruments, and their abilities to differentiate between patients with an ADHD diagnosis and non-ADHD patients referred for psychiatric assessment were examined in a naturalistic sample of 61 adult patients.

RESULTS: The area under the receiver operating characteristic curve (AUC) for the dichotomized versions of the test variables in all tests ranged from 0.61 to 0.71. The ASRS and CSS exhibited sensitivity of 90.2% and 85.4%, and specificity of 35.0% and 40.0%, respectively. Variables from the QBTest Plus showed the opposite result for the variables QBImpulsivity and QBInattention, with sensitivity of 58.5% and 36.3% and specificity of 80.0% and 100.0%. Sensitivity and specificity of QBActivity were 68.3% and 65.0%, respectively. A stepwise discriminant function analysis showed that two variables from the QBTest Plus--QBInattention and QBActivity--accounted for 22.8% of the between-group variability, with the strongest predictor being QBInattention. The function yielded an overall correct classification of 72.1%. The classification correctly identified 87.8% of patients diagnosed with ADHD and 40.0% of non-ADHD patients.

CONCLUSION: The discriminant validity of self-rating scales and the more objective measure of ADHD symptoms are poor and should be integrated generally with other sources of data.