10-year Cost-Effectiveness of Lifestyle Intervention or Metformin for the Primary Prevention of Type-2 Diabetes Mellitus – An Intent-to-Treat Analysis

The 10-year Cost-Effectiveness of Lifestyle Intervention or Metformin for the Primary Prevention of Type-2 Diabetes Mellitus – An Intent-to-Treat Analysis of Diabetes Prevention
William Herman (on behalf of the DPP/DPPOS group)
ADA 2011.

DPP was run over 3 years and the DPPOS (Diabetes Prevention Program Outcome Study) ran for a further 7-year follow up. A recent intention to treat analysis showed a persistent benefit out to 10 years.
In the lifestyle intervention there was a 31% reduction in risk of developing diabetes versus a 19% reduction in diabetes risk in the metformin treated group. It was postulated that there may be differences in cost effectiveness if diabetes were prevented.
Data on medical and non-medical costs were evaluated in the present study. From the health system perspective there was a substantial additional cost for lifestyle intervention accruing to $4500 over 10 years for lifestyle intervention and $2000 over 10 years for metformin versus $500 for placebo.
The direct medical costs for treatments other than DPP interventions were substantially greater for all 3 groups which by 10 years was an average of $25000 in each group with a trend to the placebo group costing a little more. This additional cost appeared to relate to the use of self monitoring for diabetes that developed in the placebo group. If both the cost of DPP intervention and other health costs were added then it cost more overall to treat the lifestyle intervention group.
Health utility scores however showed a different trend with the lifestyle group achieving substantial gains. Quality adjusted life years were greatest for the lifestyle group and least for the placebo group. Cost per QALY gain in the lifestyle group was $9000 (undiscounted) or $12000 (discounted) over 10 years. The metformin group was cost saving and in health effectiveness terms were in the same league as influenza vaccine whereas lifestyle intervention equated to antihypertensive therapy in terms of QALY gain. The reduced costs of medical care in the metformin group more than offset the cost of the therapy.