How do we measure psychiatric diagnoses? Implications of the choice of instruments in epilepsy

We evaluated several commonly used screening instruments for the detection of mood disorders, anxiety disorders, and attention-deficit hyperactivity disorder (ADHD). These were compared to a criterion-based standardized questionnaire, the Diagnostic Interview Survey (DIS)-IV, designed to make DSM-IV-TR diagnoses in the community-based study of childhood-onset epilepsy. The DIS-IV was administered to young adult cases with epilepsy at a 15-year follow-up assessment and compared to symptom screens administered at the same visit, and at a previous 9-year assessment. Among cases, the specificity of the DIS-IV ranged from 0.77 to 0.99 and the predictive value of a negative psychiatric diagnosis was similarly high. Sensitivity was lower, ranging from 0 to 0.77, with correspondingly low predictive value of a positive diagnosis. Symptom-based instruments assess current symptom burden and are useful for determining associations with ongoing seizures or quality of life. Criterion-based standardized interviews, such as the DIS-IV, provide psychiatric diagnoses over the lifetime, which is most useful in studies of epilepsy genetics and studies of comorbidities and prognosis of epilepsy.