Motivational enhancement therapy with and without cognitive behaviour therapy for Type 1 diabetes: economic evaluation from a randomized controlled trial

Aims: To assess the cost-effectiveness of motivational enhancement therapy and cognitive behaviour therapy for poorly controlled Type 1 diabetes.

Methods: Within-trial prospective economic evaluation from (i) health and social care and (ii) societal perspectives. Three hundred and forty-four adults with Type 1 diabetes for at least 2 years and persistent, suboptimal glycaemic control were recruited to a three-arm multi-centre randomized controlled trial in London and Manchester, UK. They were randomized to (i) usual care plus four sessions of motivational enhancement therapy (ii) usual care plus four sessions of motivational enhancement therapy and eight sessions of cognitive behaviour therapy or (iii) usual care alone. Outcomes were (i) costs, (ii) Quality-Adjusted Life Year gains measured by the EuroQol 5-dimensional health state index and the 36-item Short Form and (iii) diabetes control measured by change in HbA(1c) level at 1 year.

Results: Both intervention groups had significantly higher mean health and social care costs (+ £535 for motivational enhancement therapy and + £790 for combined motivational enhancement and cognitive behavioural therapy), but not societal costs compared with the usual-care group. There were no differences in Quality Adjusted Life Years. There was a significantly greater HbA(1c) improvement in the combined motivational enhancement and cognitive behavioural therapy group (+ 0.45%; incremental cost-effectiveness ratio = £1756), but the not in the motivational enhancement therapy group. Cost-effectiveness acceptability curves suggested that both interventions had low probabilities of cost-effectiveness based on Quality Adjusted Life Years (but high based on HbA(1c) improvements). Imputing missing costs and outcomes confirmed these findings.

Conclusions: Neither therapy was undisputedly cost-effective compared with usual care alone, but conclusions vary depending on the relative importance of clinical and quality-of-life outcomes.