Stability of the CORE-OM and the BDI-I prior to therapy: Evidence from routine practice

Background. It is important to know the stability of standard outcome measures prior to therapy over differing periods of time that map onto the realities of waiting times in routine service settings.

Method. We studied 1,684 clients who completed one or both the targeted measures Clinical Outcomes in Routine Evaluation-Outcome Measures (CORE-OM) and Beck Depression Inventory-I (BDI-I) two times, at intervals of up to 12 months, prior to beginning psychotherapy. We also selected an additional 1,623 clients who completed the CORE-OM (N=1,623), BDI-I (N=980) or both at referral, but had no records of further contact with the service.

Results. There was little change in the mean CORE-OM or BDI-I scores between referral and clinical assessment. The test-retest correlations showed substantial stability on both measures, declining only moderately at the longer intervals studied.

Conclusion. The high test-retest correlations for periods of up to 6 months suggest that psychological disturbance was both reliably measured by the CORE-OM and the BDI-I, and reasonably stable among clients waiting to be assessed. Implications for routine practice are discussed.