Cost and Outcome of BehaviouRal Activation (COBRA): a randomised controlled trial of behavioural activation versus cognitive-behavioural therapy for depression.

Background Depression is a common, debilitating and costly disorder. The best-evidenced psychological therapy – cognitive–behavioural therapy (CBT) – is complex and costly. A simpler therapy, behavioural activation (BA), may be an effective alternative. Objectives To determine the clinical effectiveness and cost-effectiveness of BA compared with CBT for depressed adults at 12 and 18 months’ follow-up, and to investigate the processes of treatments. Design Randomised controlled, non-inferiority trial stratified by depression severity, antidepressant use and recruitment site, with embedded process evaluation; and randomisation by remote computer-generated allocation. Setting Three community mental health services in England. Participants Adults aged ≥ 18 years with major depressive disorder (MDD) recruited from primary care and psychological therapy services. Interventions BA delivered by NHS junior mental health workers (MHWs); CBT by NHS psychological therapists. Outcomes Primary: depression severity (as measured via the Patient Health Questionnaire-9; PHQ-9) at 12 months. Secondary: MDD status; number of depression-free days; anxiety (as measured via the Generalised Anxiety Disorder-7); health-related quality of life (as measured via the Short Form questionnaire-36 items) at 6, 12 and 18 months; and PHQ-9 at 6 and 18 months, all collected by assessors blinded to treatment allocation. Non-inferiority margin was 1.9 PHQ-9 points. We undertook intention-to-treat (ITT) and per protocol (PP) analyses. We explored cost-effectiveness by collecting direct treatment and other health- and social-care costs and calculating quality-adjusted life-years (QALYs) using the EuroQol-5 Dimensions, three-level version, at 18 months. Results We recruited 440 participants (BA, n = 221; CBT, n = 219); 175 (79%) BA and 189 (86%) CBT participants provided ITT data and 135 (61%) BA and 151 (69%) CBT participants provided PP data. At 12 months we found that BA was non-inferior to CBT {ITT: CBT 8.4 PHQ-9 points [standard deviation (SD) 7.5 PHQ-9 points], BA 8.4 PHQ-9 points (SD 7.0 PHQ-9 points), mean difference 0.1 PHQ-9 points, 95% confidence interval (CI) –1.3 to 1.5 PHQ-9 points, p = 0.89; PP: CBT 7.9 PHQ-9 points (SD 7.3 PHQ-9 points), BA 7.8 PHQ-9 points (SD 6.5 PHQ-9 points), mean difference 0.0 PHQ-9 points, 95% CI –1.5 to 1.6 PHQ-9 points, p = 0.99}. We found no differences in secondary outcomes. We found a significant difference in mean intervention costs (BA, £975; CBT, £1235; p < 0.001), but no differences in non-intervention (hospital, community health, social care and medication costs) or total (non-intervention plus intervention) costs. Costs were lower and QALY outcomes better in the BA group, generating an incremental cost-effectiveness ratio of –£6865. The probability of BA being cost-effective compared with CBT was almost 80% at the National Institute for Health and Care Excellence’s preferred willingness-to-pay threshold of £20,000–30,000 per QALY. There were no trial-related adverse events. Limitations In this pragmatic trial many depressed participants in both groups were also taking antidepressant medication, although most had been doing so for a considerable time before entering the trial. Around one-third of participants chose not to complete a PP dose of treatment, a finding common in both psychotherapy trials and routine practice. Conclusions We found that BA is as effective as CBT, more cost-effective and can be delivered by MHWs with no professional training in psychological therapies. Future work Settings and countries with a paucity of professionally qualified psychological therapists, might choose to investigate the delivery of effective psychological therapy for depression without the need to develop an extensive and costly professional infrastructure.