Provision of financial incentives is a promising intervention for improving adherence in patients taking antipsychotic medication. We aimed to assess the effectiveness of this intervention for improving adherence to antipsychotic depot medication in patients with psychotic disorders, irrespective of their previous compliance.
We did this multicentre, open-label, randomised controlled trial at three mental health-care institutions in secondary psychiatric care services in the Netherlands. Eligible patients were aged 18–65 years, had been diagnosed with schizophrenia or another psychotic disorder, had been prescribed antipsychotic depot medication or had an indication to start using depot medication, and were participating in outpatient treatment. Patients were randomly assigned (1:1), via computer-generated randomisation with a block size of four, to receive 12 months of either treatment as usual plus a financial reward for each depot of medication received (€30 per month if fully compliant; intervention group) or treatment as usual alone (control group). Randomisation was stratified by treatment site and suspected prognostic factors: sex, comorbid substance-use disorder (absent vs present), and compliance with antipsychotic medication in the 4 months before baseline (<50% vs ≥50%). Patients, clinicians, interviewers, and research assistants were masked to group allocation before, but not after, group assignment. The primary outcome was the Medication Possession Ratio (MPR), defined as the number of depots of antipsychotic medication received divided by the total number of depots of antipsychotic medication prescribed during the 12 month intervention period. Patients were followed up for 6 months, during which time no monetary rewards were offered for taking antipsychotic medication. We did analysis by intention to treat. This trial is registered with the Nederlands Trial Register, number NTR2350.
Between May 21, 2010, and Oct 15, 2014, we randomly assigned 169 patients to the intervention group (n=84) or the control group (n=85). Primary outcome data were available for 155 (92%) patients. At baseline, the mean MPR was 76·0% (SD 28·2%) in the intervention group versus 77·9% (28·5%) in the control group. At 12 months, the mean MPR was higher in the intervention group (94·3% [SD 11·3%]) than in the control group (80·3% [19·1%]), with an adjusted difference of 14·9% (95% CI 8·9–20·9%; p<0·0001). This difference was maintained throughout the 6 month follow-up period: mean MPR of 86·6% (SD 22·2%) in the intervention group versus 76·0% (22·7%) in the control group (adjusted difference 6·5%, 95% CI 2·0–10·9; p=0·047).
Financial incentives are an effective way of improving adherence to antipsychotic depot medication among patients with psychotic disorders. Further research is needed to study the long-term effects of this intervention.