Worsening Anxiety, Irritability, Insomnia, or Panic Predicts Poorer Antidepressant Treatment Outcomes: Clinical Utility and Validation of the Concise Associated Symptom Tracking (CAST) Scale

Background: We report on the psychometric properties of the 16-item Concise Associated Symptom Tracking Scale self-report scale and its clinical utility. Methods: The 5-domain (irritability, anxiety, mania, insomnia, and panic) structure of Concise Associated Symptom Tracking Scale was validated with confirmatory factor analysis in Combining Medications to Enhance Depression Outcomes trial participants at baseline (n = 664). Correlations with other clinical measures were used for convergent and divergent validity. In participants with at least one postbaseline visit (n = 630), worsening in each Concise Associated Symptom Tracking Scale domain was defined as ≥1.28 SD increase from baseline for each visit (weeks 1, 2, 4, and 6) only. Worsening in any domain (except mania) was defined as overall worsening. Association of domain-specific and overall worsening with remission was tested with logistic regression analyses. Results: The 5-domain structure had adequate model fit on confirmatory factor analysis (GFI = 0.93, CFI = 0.89, and RMSEA = 0.07). Scores on anxiety, panic, insomnia, and mania significantly correlated with Hamilton Rating Scale for Depression anxiety subscale (r _s = 0.27), Psychiatric Diagnostic Screening Questionnaire-panic scale (r _s = 0.35), sum of 3 Quick Inventory of Depressive Symptomatology Self-Report insomnia items (r _s = 0.55), and Altman Self-Rating Mania scale (r _s = 0.41), respectively. From baseline to week 6, 5.2%, 7.5%, 47.6%, 15.6%, 6.2%, and 27.6% participants (n = 630) experienced irritability, anxiety, mania, insomnia, panic, and overall worsening, respectively. Participants with overall worsening were less likely to remit (31.6%) than those without any worsening (43.9%; odds ratio = 0.53, 95% CI = 0.36, 0.78). Conclusion: The 16-item Concise Associated Symptom Tracking Scale self-report has acceptable psychometric properties. Clinically significant worsening of irritability, anxiety, insomnia, or panic with antidepressant treatment is associated with poorer outcomes.