Assessing anxious features in depressed outpatients

Both the 17-item Hamilton Rating Scale for Depression (HRSD ₁₇) and 30-item Inventory of Depressive Symptomatology - Clinician-rated (IDS-C ₃₀) contain a subscale that assesses anxious symptoms. We used classical test theory and item response theory methods to assess and compare the psychometric properties of the two anxiety subscales (HRSD _ANX and IDS-C _ANX) in a large sample (N=3453) of outpatients with non-psychotic major depressive disorder in the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) study. Approximately 48% of evaluable participants had at least one concurrent anxiety disorder by the self-report Psychiatric Diagnostic Screening Questionnaire (PDSQ). The HRSD _ANX and IDS-C _ANX were highly correlated (r=0.75) and both had moderate internal consistency given their limited number of items (HRSD _ANX Cronbach's alpha=0.48; IDS-C _ANX Cronbach's alpha=0.58). The optimal threshold for ascribing the presence/absence of anxious features was found at a total score of eight or nine for the HRSD _ANX and seven or eight for the IDS-C _ANX. It would seem beneficial to delete item 17 (loss of insight) from the HRSD _ANX as it negatively correlated with the scale's total score. Both the HRSD _ANX and IDS-C _ANX subscales have acceptable psychometric properties and can be used to identify anxious features for clinical or research purposes.