Psychometrics of the Self-Report Concise Associated Symptoms Tracking Scale (CAST-SR): Results From the STRIDE (CTN-0037) Study.

OBJECTIVE: The self-report Concise Associated Symptoms Tracking Scale (CAST-SR) was developed to track mania, irritability, anxiety, panic, and insomnia symptoms among depressed outpatients receiving antidepressant medication. Given the overlap between these domains, depression, and stimulant use disorders, we reexamined CAST-SR psychometrics in a novel sample: individuals with stimulant use disorder receiving aerobic exercise or health education interventions.

METHODS: Using the subsample of stimulant-dependent (following DSM-IV criteria) individuals prescribed antidepressants (N = 124) from the multisite Stimulant Reduction Intervention Using Dosed Exercise (CTN-0037) trial (total sample N = 302), conducted July 2010 to February 2013, we analyzed CAST-SR data collected at the first assessment after participant's discharge from residential treatment. We also evaluated the convergent/discriminant validity of the CAST-SR with several self-report questionnaires.

RESULTS: Confirmatory factor analysis revealed a 12-item measure composed of 4 factors: irritability, anxiety, panic, and insomnia. This factor structure loaded only in participants prescribed antidepressant medication, not in those who were not prescribed antidepressants. These results replicate the original CAST-SR factor structure, except for the mania factor, which failed to load. Internal consistency was high (α = 0.92 for total scale and α = 0.78-0.89 for the 4 factors), and convergent validity was established, especially for the insomnia and irritability factors, alongside the total score with depressive symptoms, insomnia, quality of life, suicide risk, and physical health measures.

CONCLUSIONS: These results demonstrate the factor structure, reliability, and validity of the CAST-SR in a novel population of only individuals with stimulant use disorders receiving both exercise/health education interventions and antidepressant medication.

TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01141608.