Abbreviated assessment of psychopathology in patients with suspected seizure disorders.

Abstract

Psychopathology is common in patients undergoing investigation for seizure-related disorders. Psychometric examination using self-report instruments, such as the Symptom Checklist 90 - Revised (SCL-90-R), can assist diagnosis. The SCL-90-R, however, is a lengthy instrument and might not be tolerated by all patients. We assessed several abbreviated forms of the SCL-90-R in patients undergoing video encephalographic monitoring (VEM). Six hundred eighty-seven patients completed the SCL-90-R, and scores were computed for the full SCL-90-R and five abbreviated forms. Correlations and mean differences were computed between different forms. Classification accuracy was assessed via receiver operating characteristic (ROC) curves, and measurements models were examined using confirmatory factor analysis (CFA). All abbreviated forms were strongly correlated with the SCL-90-R for general psychopathology (r = 0.93-0.99), depression (r = 0.89-0.95), anxiety (r = 0.97-0.98), psychosis (r = 0.95-0.99), and obsessive-compulsive symptoms (r = 0.97). Classification performance was similar across forms for depression and anxiety, with high negative predictive values (0.90-0.94) and lower positive predictive values (0.34-0.38). Classification performance for psychotic and obsessive-compulsive disorders was poor. Differences were observed between the full SCL-90-R and its abbreviated forms across most domains (d = 0.00-0.65). The published measurement model was most strongly validated for the SCL-27, SCL-14, and the SCL-K-9. These five SCL-90-R abbreviated forms show high convergent validity with the full version. In patients undergoing investigation for seizure-related disorders, the Brief Symptom Inventory full form (BSI) or short form (BSI-18) is most appropriate where screening for both depression and anxiety is required. The SCL-K-9 is appropriate when only a single measure of global psychological distress is required. None of the instruments were able to detect psychotic or obsessive-compulsive symptoms with great accuracy. Caution should be exercised when making direct comparisons across the different forms.