Health economic modeling techniques were used to establish whether implementing the active treatments used in the Diabetes Prevention Program (DPP) would be cost-effective in Australia, France, Germany, Switzerland and the United Kingdom.

• Original DPP participants
• Overweight patients with impaired glucose tolerance.

Not reported.

• Recruitment: Recruitment of DPP study participants and additional study participants not reported.  
• Design: Cost-effectiveness analysis
  • A Markov model simulated three states: Impaired glucose tolerance (IGT); type 2 diabetes mellitus; deceased-using probabilities from the Diabetes Prevention Program and published data
  • Country-specific direct costs were used throughout.
• Intervention: From the DPP; Metformin (plus standard lifestyle advice) or intensive lifestyle changes vs. standard lifestyle advice only
• Statistical analysis: 95% confidence intervals were used in the sensitivity analysis.

Timing of Measurements

Trial period lasted three years.

Dependent Variables

• Number of years free of diabetes, percentage of patients developing diabetes, life expectancy and total lifetime costs per patient (including costs of implementing the different interventions in country specific settings and the global costs of being in the states of IGT and type 2 diabetes were calculated for each treatment arm
• Incremental cost-effectiveness ratios calculated in terms of costs per life-year gained between the treatment arms. 

Independent Variables

Three treatment arms of the DPP were compared

1. Intensive lifestyle changes: With goals of great or equal to 7% weight loss or weight maintenance and greater or equal 150 minutes per week of physical activity. Consisted of a 16-lesson, goal-oriented education program that taught behavioral self-management strategies for weight loss and physical activity.
2. Meformin plus standard advice on diet and exercise: Metformin use with target doses 850mg BID. Diet and exercise delivered as written information and in a yearly 30-minute individual consultation. Participants were reviewed annually by a medical case manager.
3. Control group: Patients took placebo instead of metformin. They received standard advice on diet and exercise (same as metformin group) and an annual review session by a medical case manager.

Control Variables

All costs were expressed in year-2002 Euros. 

• Initial N: 3,234 DPP participants randomized. Cohort of patients in this analysis constructed to resemble the DPP study population.
• Age: Mean age 50.6 years
• Other relevant demographics: Mean body weight, 94.2kg
• Location: Australia, France, Germany, Switzerland and United Kingdom.

Other Findings

• Assuming only within-trial effects and costs of interventions, both metformin and intensive lifestyle changes improved life expectancy vs. control
• Mean improvements in non-discounted life expectancy were 0.11 and 0.22 years for metformin and intensive lifestyle changes, respectively
• Both interventions were associated with cost savings versus control in all countries except the United Kingdom, where a small increase in costs was observed in both intervention arms
• When a lifetime effect of interventions was assumed, incremental improvements in life expectancy were 0.35 and 0.90 years for metformin and intensive lifestyle changes, respectively
• Results were sensitive to probabilities of developing type 2 diabetes, the projected long-term duration of effect of interventions after the three-year trial period, the relative risk of mortality for type 2 diabetes compared with impaired glucose tolerance and the costs of implementing the interventions.

Based on probabilities from the DPP and published data, in this model analysis, incorporation of the DPP interventions into clinical practice in five developed countries was projected to lead to an increase in diabetes-free years of life, improvements in life expectancy, and either cost savings or minor increases in costs compared with standard lifestyle advice in a population with impaired glucose tolerance. Thus, financial constraints should not prevent the implementation of diabetes mellitus prevention programs.

Cohort of patients resembling DPP not well described. Authors note the following limitations:

• Degree of uncertainty in translating data from a carefully controlled clinical trial in one country to routine clinical practice in another
• No direct non-medical or indirect costs were included in the estimation of the costs of the DPP interventions
• Variation by country did not adequately reflect country-specific practice patterns.