Financial incentives to improve adherence to antipsychotic maintenance medication in non-adherent patients: a cluster randomised controlled trial

Background: Poor adherence to long-term antipsychotic injectable (LAI) medication in patients with psychotic disorders is associated with a range of negative outcomes. No psychosocial intervention has been found to be consistently effective in improving adherence. Objectives: To test whether or not offering financial incentives is effective and cost-effective in improving adherence and to explore patient and clinician experiences with such incentives. Design: A cluster randomised controlled trial with economic and nested qualitative evaluation. The intervention period lasted for 12 months with 24 months' follow-up. The unit of randomisation was mental health teams in the community. Setting: Community teams in secondary mental health care. Participants: Patients with a diagnosis of schizophrenia, schizoaffective psychosis or bipolar illness, receiving <= 75% of their prescribed LAI medication. In total, 73 teams with 141 patients (intervention n = 78 and control n = 63) were included. Interventions: Participants in the intervention group received pound 15 for each LAI medication. Patients in the control group received treatment as usual. Main outcome measures: Primary outcome: adherence to LAI medication (the percentage of received out of those prescribed). Secondary outcomes: percentage of patients with at least 95% adherence; clinical global improvement; subjective quality of life; satisfaction with medication; hospitalisation; adverse events; and costs. Qualitative evaluation: semistructured interviews with patients in the intervention group and their clinicians. Results: Primary outcome: outcome data were available for 131 patients. Baseline adherence was 69% in the intervention group and 67% in the control group. During the intervention period, adherence was significantly higher in the intervention group than in the control group (85% vs. 71%) [ adjusted mean difference 11.5%, 95% confidence interval (CI) 3.9% to 19.0%; p = 0.003]. Secondary outcome: patients in the intervention group showed statistically significant improvement in adherence of at least 95% (adjusted odds ratio 8.21, 95% CI 2.00 to 33.67; p = 0.003) and subjective quality of life (difference in means 0.71, 95% CI 0.26 to 1.15; p = 0.002). Follow-ups: after incentives stopped, adherence did not differ significantly between groups, neither during the first 6 months (adjusted difference in means - 7.4%, 95% CI - 17.0% to 2.1%; p = 0.175) nor during the period from month 7 to month 24 (difference in means - 5.7%, 95% CI - 13.1% to 1.7%; p = 0.130). Cost-effectiveness: the average costs of the financial incentives was 303 pound. Overall costs per patient were somewhat higher in the intervention group, but the difference was not significant. Semistructured interviews: the majority of patients and clinicians reported positive experiences with the incentives beyond their monetary value. These included improvement in the therapeutic relationship. The majority of both patients and clinicians perceived no negative impact after the intervention was stopped after 1 year. Conclusions: Financial incentives are effective in improving adherence to LAI medication. Health-care costs (including costs of the financial incentive) are unlikely to be increased substantially by this intervention. Once the incentives stop, the advantage is not maintained. The experiences of both patients and clinicians are largely, but not exclusively, positive. Whether or not financial incentives are effective for patients with more favourable background, those on oral mediation or for shorter or longer time periods remains unknown.