OBJECTIVES: Depression is a common and debilitating mental-health condition. Antidepressants are recommended as first-line treatment, often taken for months or years after a depressive episode. The ANTLER study investigated the impact of tapered discontinuation of medication in well patients, compared to maintenance treatment, to determine whether maintenance treatment prevented relapse. The objective was to calculate the impact on health-related quality-of-life (HRQoL) and English National Health Service (NHS) costs of experiencing a depression relapse, using ANTLER patient-level trial data.

METHODS: 478 participants from 150 England general practices were recruited to a randomised, double-blind trial (ANTLER). Utility scores were calculated from the EQ-5D-5L preference-based measure of HRQoL using the Value Set for England and crosswalk tariffs, and the Short-Form 12 (SF-6D tariff), collected every 3 months. Six-monthly costs were calculated by applying unit costs to resource use collected from primary care electronic records and self-completed questionnaires at baseline, 6 and 12 months. Relapse was assessed every 3 months using the retrospective Clinical Interview Schedule - Revised (rCIS-R) to identify the onset of a depressive episode over the previous 3 months. Adjustments included randomised group, baseline ANTLER medication, baseline disease severity and site.

RESULTS: Relapse corresponded to a significant reduction in HRQoL for that quarter, in all three utility tariffs, and increased primary care consultation costs by a mean of £28.31 (95% CI 12.62 to 44.00) per patient. There was no significant difference in self-reported costs (£5.76, 95% CI -14.97 to 26.49).

CONCLUSIONS: Depression relapse corresponded to significant reductions in HRQoL for patients. This agreed with previous work suggesting that generic preference-based measures are valid in common mental-health disorders, facilitating comparability with economic evaluations in other disease areas. This work also presents evidence of the cost of a depression relapse to the English NHS, an area where high-quality evidence has previously been lacking.