Evaluating the Short-Term Costs and Benefits of a Nationwide Diabetes Prevention Programme in England: Retrospective Observational Study.

Background: Prevention programmes typically incur short-term costs and uncertain long-term benefits. We use the National Health Service (NHS) England Diabetes Prevention Programme (NHS-DPP) to investigate whether behaviour change programmes may be cost-effective even within the short-term participation period.

Methods: We analysed 384,611 referrals between June 2016 and March 2019. We estimated NHS costs using implementation costs and provider payments. We used linear regressions to relate utility changes to the number of sessions attended, based on responses to the five-level EQ-5D (EQ-5D-5L) at baseline and final session for 18,959 participants. We then calculated the corresponding quality-adjusted life year (QALY) change for all 384,611 referrals by combining the estimated regression coefficients with the observed level of attendance, with individuals that did not attend any programme sessions being assumed to experience zero benefit. In secondary analysis, we added weight change, recorded for 18,105 participants to the regression and applied predicted values to all referrals with missing weight change values estimated using multiple imputation with chained equations. We then estimated the cost-per-QALY generated.

Results: Average cost per referral was £119 (standard deviation: £118; 2020 price year, UK £ Sterling). Each session attended was associated with a 0.0042 increase in utility (95% confidence interval (CI): 0.0025-0.0059). This generated 1,773 QALYs across all referrals (95% CI: 889-2,656). Cost-per-QALY was £24,929 (95% CI: £16,635-49,720) when implementation costs were excluded. Secondary analysis showed each session attended and kilogram of weight lost were associated with 0.0034 (95% CI: 0.0016-0.0051) and 0.0025 (95% CI: 0.0020-0.0031) increases in utility, respectively. These generated 1,542 QALYs, at a cost-per-QALY of £28,661 when implementation costs were excluded.

Conclusion: Participants experienced small utility gains from session attendance and weight loss during their programme participation. These benefits alone made this low-cost behaviour change programme potentially cost-effective in the short-term.