SAN DIEGO – Few medical interventions both improve health and save money. Treating prediabetes with metformin is one of them, according to 10-year follow-up data from the Diabetes Prevention Program.
Intensive lifestyle intervention, the other treatment arm in the randomized, placebo-controlled Diabetes Prevention Program (DPP) study, did an even better job at improving health and quality of life, and at a favorable cost when compared with some common medical interventions for other diagnoses, Dr. William H. Herman and his associates reported at the annual scientific sessions of the American Diabetes Association.
Most of the costs for the placebo group in the ensuing decade were related to conversion of subjects’ prediabetes to diabetes, explained Dr. Herman, professor of medicine and epidemiology at the University of Michigan, Ann Arbor.
At baseline, all 3,234 participants in the DPP were nondiabetic, were overweight or obese, and had impaired glucose tolerance and an elevated fasting glucose level.
Metformin treatment (850 mg b.i.d.) reduced overall costs for medical care in those 10 years by $1,700 per person, and lifestyle intervention reduced those costs by $2,600 per person. After factoring in the costs of the interventions, the researchers found that metformin treatment produced a savings of $30 per patient compared with placebo over the 10 years.
Dr. William H. Herman
The cost-saving benefits of metformin for people at high risk of diabetes puts this preventive intervention in a league with prenatal care, pediatric immunizations, and influenza vaccinations for people older than 65 years, Dr. Herman said. Only 1 in 10 medical interventions are cost-saving, he noted.
With the lifestyle intervention, overall costs were $1,500 per person greater than placebo, a price tag that puts lifestyle intervention for prediabetes in a league with some of the most widely accepted medical interventions when converted for comparison into quality-adjusted life-years gained.
In simple terms, the cost for a quality-adjusted life-year gained is the price "to buy 1 year of life in essentially perfect health," he explained.
In this study, the cost per quality-adjusted life-year gained with the intensive lifestyle intervention compared with the placebo group was $12,000. That $12,000 is on the low end of a $10,000-$50,000 range that’s widely accepted for medical interventions, including the use of beta-blockers after MI, the use of antihypertensive therapy for patients with very high diastolic blood pressure (greater than 105 mm Hg), or the use of statins for secondary prevention of cardiovascular disease in patients who’ve had an MI. Dialysis for end-stage renal disease costs $50,000-$100,000 per quality-adjusted life-year gained.
When the DPP results first came out, "The reaction in the medical community was, ‘This is great, but we don’t have the resources to implement it,’ " Dr. Herman said. Controversy continued due to conflicting results from analyses that modeled cost effectiveness over time based on the 3-year results of the DPP. The current study used real-life cost data collected prospectively for the study period and the following 7 years.
The results show that for patients with prediabetes, "metformin is cost saving. Intensive lifestyle intervention, though not cost saving, is extremely cost effective," Dr. Herman said. "It represents good value for the money."
The DPP’s lifestyle intervention aimed for a 7% reduction in body weight and 150 minutes per week of moderately intense physical activity, usually 30 minutes per day of brisk walking 5 days per week. Patients were asked to attend 16 sessions in a 6-month period for nutritional and exercise guidance and received ongoing follow-up with a case manager. After 3 years, the incidence of diabetes was 58% lower in the lifestyle intervention group and 31% lower with metformin compared with the placebo group (N. Engl. J. Med. 2002;346:393-403). The diabetes incidence was 5 cases per 100 person-years in the lifestyle group compared with 8 in the metformin group, and 11 in the placebo group.
During the next 7 years, patients in the metformin group were encouraged to continue the medication, and those in the lifestyle intervention group were offered a less intensive lifestyle intervention with fewer individual sessions. At the 10-year mark, the risk for developing diabetes was 34% less in the lifestyle intervention group and 18% less in the metformin group compared with the control group, Dr. Herman said. Quality of life was rated significantly higher in the metformin group compared with the placebo group, and significantly higher in the lifestyle intervention group compared with the metformin or placebo groups.
Implementation of a lifestyle intervention should be as simple as writing a prescription for a pill to prevent diabetes, Dr. Herman suggested. One way to build access to lifestyle interventions might be to locate them in cardiac rehabilitation centers, which already contain the facilities needed for exercise and other components of the intervention.