A pragmatic randomised controlled trial to evaluate the cost-effectiveness of a physical activity intervention as a treatment for depression: the treating depression with physical activity (TREAD) trial

Objective: The TREAting Depression with physical activity (TREAD) study investigated the cost-effectiveness of a physical activity intervention, in addition to usual general practitioner care, as a treatment for people with depression. Design: An individually randomised, pragmatic, multicentre randomised controlled trial with follow-up at 4, 8 and 12 months. A subset of participants took part in a qualitative study that investigated the acceptability and perceived benefits of the intervention. Setting: General practices in the Bristol and Exeter areas. Participants: Aged 18-69 years with an International Statistical Classification of Diseases and Related Health Problems, 10th Edition (ICD-10) diagnosis of depression and scoring >= 14 on the Beck Depression Inventory (BDI). Those who were unable to complete self-administered questionnaires in English, with medical contraindications to physical activity or with psychosis, bipolar disorder or serious drug abuse were excluded. Interventions: We devised an intervention designed to encourage choice and autonomy in the adoption of physical activity. It consisted of up to three face-to-face and ten telephone contacts delivered by a trained physical activity facilitator over an 8-month period. Main outcome measures: The primary outcome was the BDI score measured at 4 months. Secondary outcomes included depressive symptoms over the 12 months and quality of life, antidepressant use and level of physical activity. Results: The study recruited 361 patients, with 182 randomised to the intervention arm and 179 to the usual care arm; there was 80% retention at the 4-month follow-up. The intervention group had a slightly lower BDI score at 4 months [-0.54, 95% confidence interval (Cl) -3.06 to 1.99] but there was no evidence that the intervention improved outcome for depression. Neither was there any evidence to suggest a difference in the prescription of or self-reported use of antidepressants. However, the amount of physical activity undertaken by those who had received the intervention was increased (odds ratio 2.3, 95% CI 1.3 to 3.9) and was sustained beyond the end of the intervention. From a health-care perspective, the intervention group was more costly than the usual care group, with the cost of the intervention 220 per person on average. It is therefore extremely unlikely that the intervention is cost-effective as a treatment for depression using current willingness-to-pay thresholds. Conclusions: This physical activity intervention is very unlikely to lead to any clinical benefit in terms of depressive symptoms or to be a cost-effective treatment for depression. Previous research has reported some benefit and there are three possible reasons for this discrepancy: first, even though the intervention increased self-reported physical activity, the increase in activity was not sufficiently large to lead to a measurable influence; second, only more vigorous activity might be of benefit; and third, previous studies had recruited individuals with a pre-existing commitment to physical activity. Future research is needed to identify and explain the mechanisms by which depression might be effectively treated, including, in particular, specific guidance on the optimum type, intensity and duration of physical activity required to produce a therapeutic effect.