The effect of a brief action planning intervention on adherence to double-blind study medication compared to a standard trial protocol in the Atorvastatin in Factorial with Omega EE90 Risk Reduction in Diabetes (AFORRD) clinical trial: a cluster randomised sub-study

AIMS: Clinical trial patients are highly motivated but may encounter difficulty in taking study medication regularly when treatment burden is substantial. We assessed a brief behavioural intervention, given in addition to a standard trial protocol. METHODS: We performed a two-arm adherence sub-study, within a twelve-month randomised controlled drug trial evaluating the impact of statin and/or omega-3 EE90 treatment in 800 patients with type 2 diabetes, in 59 United Kingdom general practices cluster-randomised to action-planning or control groups. The former delivered an initial written exercise prompting participants to formulate action-plans to take study medication regularly, with brief nurse encouragement to use action-plans at later visits, whilst the latter followed the standard trial protocol. The primary outcome was proportion of days on which study medication were taken as intended measured by electronic medication containers. RESULTS: Adjusted mean (95% CI) proportion of days with medication taken as intended was 79.3% (76.3% to 82.3%) for the 30 action-planning practices (321 participants), compared with 78.5% (75.8% to 81.1%) for the 29 control group practices (479 participants, with a mean intervention effect of 0.9% (95%CI -3.1% to +4.9%, p=0.67). Adjusted odds ratios for ≥80% trial medication adherence for action-planning compared with control practices were 1.29 (0.90 to 1.84) and 1.38 (0.96 to 1.99) respectively. CONCLUSIONS: Low-intensity action-planning interventions used alone are unlikely to have a clinically important impact on medication adherence. These findings, do not exclude their contribution, as part of a multifactorial intervention, to improving treatment adherence. ISRCTN number 76737502.