William H. Herman

The Cost-Effectiveness of Lifestyle Modification or Metformin in Preventing Type 2 Diabetes in Adults with Impaired Glucose Tolerance

Context The Diabetes Prevention Program (DPP) showed that lifestyle changes or metformin effectively decreased the development of type 2 diabetes in adults with impaired glucose tolerance. The economics of these interventions is important to policymakers. Contribution This cost-effectiveness model estimates that the DPP life-style intervention would cost society about

Rosiglitazone-associated fractures in type 2 diabetes: an Analysis from A Diabetes Outcome Progression Trial (ADOPT).

8800 and metformin would cost about

Prevalence and Determinants of Insulin Resistance Among U.S. Adolescents A population-based study

29900 per quality-adjusted life-year saved. While lifestyle intervention had a favorable cost-effectiveness profile at any adult age, metformin was not cost-effective after age 65 years. Implications The cost-effectiveness of lifestyle intervention to prevent type 2 diabetes in high-risk individuals is within the range that American society typically finds acceptable for health care interventions. The Editors During the past half century, the number of persons with diagnosed diabetes in the United States has increased 4- to 6-fold (1). Recent large clinical trials from Asia, Europe, and North America have demonstrated that behavioral and medication interventions can delay or prevent the development of type 2 diabetes in persons with impaired glucose tolerance, which is defined by a plasma glucose level between 7.77 mmol/L (140 mg/dL) and 11.04 mmol/L (199 mg/dL) 2 hours after a 75-g oral glucose load (2-6). The Diabetes Prevention Program (DPP) randomly assigned 3234 nondiabetic persons 25 years of age or older with impaired glucose tolerance and fasting glucose levels between 5.27 mmol/L (95 mg/dL) and 6.94 mmol/L (125 mg/dL) to placebo; a lifestyle-modification program with the goals of at least a 7% weight loss and 150 minutes of physical activity per week; or metformin, 850 mg twice daily (4). The mean age of participants was 51 years, and the mean body mass index was 34.0 kg/m2; 68% were women and 45% were members of minority groups (4). The average follow-up was 2.8 years. Compared with the placebo intervention, the lifestyle intervention reduced the incidence of type 2 diabetes by 58% and the metformin intervention reduced the incidence of type 2 diabetes by 31% (4). We have previously described the costs of the DPP interventions and their cost-effectiveness within the 3-year trial period (7, 8). In this analysis, we project the costs, health outcomes, and cost-effectiveness of the DPP lifestyle and metformin interventions over a lifetime relative to the placebo intervention. Methods Clinical Trial The lifestyle intervention involved a healthy, low-calorie, low-fat diet and moderate physical activity, such as brisk walking. The lifestyle intervention was implemented with a 16-lesson core curriculum covering diet, exercise, and behavior modification that was taught by case managers on a one-on-one basis, followed by individual sessions (usually monthly) and group sessions with case managers (9). At the end of the study, 38% of participants in the lifestyle intervention group had lost at least 7% of their initial body weight. The metformin and placebo interventions were initiated at a dosage of 850 mg once a day. At 1 month, the dosage of metformin or placebo was increased to 850 mg twice daily. Case managers reinforced adherence during individual quarterly sessions (10). At the end of the study, 72% of participants in the metformin intervention group and 77% of participants in the placebo intervention group took at least 80% of the prescribed dose. All participants received standard lifestyle recommendations through written information and an annual 20- to 30-minute individual session that emphasized the importance of a healthy lifestyle (10). Simulation Model We assessed the progression from impaired glucose tolerance to onset of diabetes to clinically diagnosed diabetes to diabetes with complications and death by using a lifetime simulation model originally developed by the Centers for Disease Control and Prevention and Research Triangle Institute International. The model has a Markov structure and includes annual transition probabilities between disease states (11). In addition to disease progression, the model tracks costs and quality-adjusted life-years (QALYs). The model has been described elsewhere (11). For our analyses, we modified the model to include data from the DPP on progression, costs, and quality of life associated with impaired glucose tolerance, data from the United Kingdom Prospective Diabetes Study (UKPDS) on diabetes progression and complications, and new data on cost and quality of life associated with diabetes. A technical report describing the model is available. Supplement. Technical Report Disease Progression, Complications, and Comorbid Conditions Impaired Glucose Tolerance to Onset of Type 2 Diabetes We analyzed data from the DPP to assess the annual hazard of diabetes onset in the lifestyle, metformin, and placebo intervention groups. For patients receiving the placebo intervention, the annual hazard of diabetes onset was 10.8 per 100 person-years. At 3 years of follow-up, the risk reductions for the lifestyle and metformin interventions were 55.8% and 29.9%, respectively. In the base-case analysis, we assumed that the lifestyle and metformin interventions would be applied until diabetes onset and that the health and quality-of-life benefits associated with the interventions persisted until diabetes onset. Complications and Comorbid Conditions Associated with Impaired Glucose Tolerance We analyzed data from the DPP and other published sources to assess the prevalence of complications and comorbid conditions in participants with impaired glucose tolerance. At baseline, 6.0% of DPP participants had microalbuminuria and 0.4% had nephropathy. The DPP did not measure peripheral neuropathy, but previous studies found that the prevalence of neuropathy in persons with impaired glucose tolerance was 74% of that in persons with newly diagnosed type 2 diabetes (12) and 12.3% of persons with newly diagnosed type 2 diabetes have neuropathy (13). Therefore, we assumed that at baseline, 8.5% of DPP participants had clinical neuropathy. At baseline, 28% of DPP participants had hypertension, 45% had dyslipidemia, 7% were smokers, 1.1% had a history of cerebrovascular disease, and 2.0% had a history of myocardial infarction. No other complications were present. We assumed that during impaired glucose tolerance, microvascular or neuropathic complications would not progress. We assumed that hypertension and dyslipidemia developed at the rates observed in the DPP. On the basis of 2 large studies (14, 15), we assumed that the incidences of coronary heart disease and cerebrovascular disease in patients with impaired glucose tolerance were 58% and 56%, respectively, of those observed in patients with type 2 diabetes. We further assumed that nondiabetes-related mortality for persons with impaired glucose tolerance was the same as for persons with diabetes (16). Onset of Type 2 Diabetes to Clinical Diagnosis of Type 2 Diabetes In the DPP, participants were tested for diabetes every 6 months; diabetes was diagnosed at onset. In routine clinical practice, type 2 diabetes is estimated to develop 8 to 12 years before its clinical diagnosis (17, 18). In our base-case analysis, we therefore assumed that a 10-year delay occurred between the onset and clinical diagnosis of diabetes. Participants in the DPP had a mean hemoglobin A1c level of 6.4% at the onset of diabetes. Participants in the UKPDS had a mean hemoglobin A1c of 7.1% after a dietary run-in period but before randomization (13). Both DPP placebo participants and UKPDS participants received standard lifestyle recommendations. Accordingly, we assumed that during the 10-year interval between onset and clinical diagnosis of diabetes, patients were treated for type 2 diabetes and that hemoglobin A1c level increased at 0.07% per year from 6.4% to 7.1%. Complications and Comorbid Conditions Associated with Undiagnosed Diabetes We further assumed that between onset and clinical diagnosis of diabetes, microvascular and neuropathic complications progressed slowly, such that by clinical diagnosis of type 2 diabetes, their prevalence reached the level observed in the UKPDS cohort at randomization (13, 19, 20). We assumed that blood pressure and lipid levels progressed as they did in DPP participants and that cardiovascular complications occurred as they would in type 2 diabetes according to risk factors and hemglobin A1c level (21, 22). Clinical Diagnosis of Type 2 Diabetes to Diabetes with Complications and Death We assumed that after clinical diagnosis, all persons with type 2 diabetes received intensive glycemic management as described in the UKPDS (13). We modeled changes in hemoglobin A1c and diabetes treatments to reflect those observed in the UKPDS intensive therapy group. We based risk for retinopathy progression on UKPDS 38 (23), risk for nephropathy progression on UKPDS 64 (20), and risk for neuropathy progression on UKPDS 33 (13). We based risk for cerebrovascular disease on UKPDS 60 (22) and risk for coronary heart disease on UKPDS 56 (21). Costs Costs of Impaired Glucose Tolerance To estimate the total direct medical costs of impaired glucose tolerance, we considered the costs of the DPP interventions (the cost of identifying participants, implementing and maintaining the interventions, and monitoring and treating the side effects of the interventions) and the costs of the medical care outside the DPP (7). In analyses from the perspective of society, we included both direct medical costs and direct nonmedical costs. We did not include indirect costs because they are captured in the assessment of QALYs (24). Table 1 shows the total direct medical costs by treatment group, sex, and year in the DPP (7). Costs were higher in the lifestyle and metformin interventions than in the placebo intervention and higher in women than in men. Costs decreased over time in all 3 intervention groups but after year 1 tended to decrease more in the lifestyle than t

A New Look at Screening and Diagnosing Diabetes Mellitus

OBJECTIVE—The purpose of this study was to examine possible factors associated with the increased risk of fractures observed with rosiglitazone in A Diabetes Outcome Progression Trial (ADOPT). RESEARCH DESIGN AND METHODS—Data from the 1,840 women and 2,511 men randomly assigned in ADOPT to rosiglitazone, metformin, or glyburide for a median of 4.0 years were examined with respect to time to first fracture, rates of occurrence, and sites of fractures. RESULTS—In men, fracture rates did not differ between treatment groups. In women, at least one fracture was reported with rosiglitazone in 60 patients (9.3% of patients, 2.74 per 100 patient-years), metformin in 30 patients (5.1%, 1.54 per 100 patient-years), and glyburide in 21 patients (3.5%, 1.29 per 100 patient-years). The cumulative incidence (95% CI) of fractures in women at 5 years was 15.1% (11.2–19.1) with rosiglitazone, 7.3% (4.4–10.1) with metformin, and 7.7% (3.7–11.7) with glyburide, representing hazard ratios (95% CI) of 1.81 (1.17–2.80) and 2.13 (1.30–3.51) for rosiglitazone compared with metformin and glyburide, respectively. The increase in fractures with rosiglitazone occurred in pre- and postmenopausal women, and fractures were seen predominantly in the lower and upper limbs. No particular risk factor underlying the increased fractures in female patients who received rosiglitazone therapy was identified. CONCLUSIONS—Further investigation into the risk factors and underlying pathophysiology for the increased fracture rate in women taking rosiglitazone is required to relate them to preclinical data and better understand the clinical implications of and possible interventions for these findings.

Rosiglitazone Associated Fractures in Type 2 Diabetes: An Analysis From ADOPT

OBJECTIVE—We sought to examine the distribution of insulin and homeostasis model assessment of insulin resistance (HOMA-IR) and associations of HOMA-IR with sex, race/ethnicity, age, and weight status, as measured by BMI, among U.S. adolescents. RESEARCH DESIGN AND METHODS—Of 4,902 adolescents aged 12–19 years who participated in the National Health and Nutrition Examination Survey 1999–2002, analysis was performed for a nationally representative subsample of 1,802 adolescents without diabetes who had fasting laboratory measurements. The main outcome measure was HOMA-IR, calculated from fasting insulin and glucose and log transformed for multiple linear regression analyses. RESULTS—In adjusted regression models that included age and weight status, girls had higher HOMA-IR than boys and Mexican-American children had higher HOMA-IR levels than white children. There were no significant differences in adjusted HOMA-IR between black and white children. Obese children (BMI ≥95th percentile) had significantly higher levels of HOMA-IR compared with children of normal weight (BMI <85th percentile) in adjusted comparisons (mean HOMA-IR 4.93 [95% CI 4.56–5.35] vs. 2.30 [2.21–2.39], respectively). Weight status was by far the most important determinant of insulin resistance, accounting for 29.1% of the variance in HOMA-IR. The prevalence of insulin resistance in obese adolescents was 52.1% (95% CI 44.5–59.8). CONCLUSIONS—Obesity in U.S. adolescents represents the most important risk factor for insulin resistance, independent of sex, age, or race/ethnicity. The prevalence of insulin resistance in obese children foreshadows a worrisome trend for the burden of type 2 diabetes in the U.S.

Model of Complications of NIDDM: II. Analysis of the health benefits and cost-effectiveness of treating NIDDM with the goal of normoglycemia

OBJECTIVE Diabetes is underdiagnosed. About one third of people with diabetes do not know they have it, and the average lag between onset and diagnosis is 7 yr. This report reconsiders the criteria for diagnosing diabetes and recommends screening criteria to make case finding easier for clinicians and patients. PARTICIPANTS R.M.B. invited experts in the area of diagnosis, monitoring, and management of diabetes to form a panel to review the literature and develop consensus regarding the screening and diagnosis of diabetes with particular reference to the use of hemoglobin A1c (HbA1c). Participants met in open session and by E-mail thereafter. Metrika, Inc. sponsored the meeting. EVIDENCE A literature search was performed using standard search engines. CONSENSUS PROCESS The panel heard each members discussion of the issues, reviewing evidence prior to drafting conclusions. Principal conclusions were agreed on, and then specific cut points were discussed in an iterative consensus process. CONCLUSIONS The main factors in support of using HbA1c as a screening and diagnostic test include: 1) HbA1c does not require patients to be fasting; 2) HbA1c reflects longer-term glycemia than does plasma glucose; 3) HbA1c laboratory methods are now well standardized and reliable; and 4) errors caused by nonglycemic factors affecting HbA1c such as hemoglobinopathies are infrequent and can be minimized by confirming the diagnosis of diabetes with a plasma glucose (PG)-specific test. Specific recommendations include: 1) screening standards should be established that prompt further testing and closer follow-up, including fasting PG of 100 mg/dl or greater, random PG of 130 mg/dl or greater, or HbA1c greater than 6.0%; 2) HbA1c of 6.5-6.9% or greater, confirmed by a PG-specific test (fasting plasma glucose or oral glucose tolerance test), should establish the diagnosis of diabetes; and 3) HbA1c of 7% or greater, confirmed by another HbA1c- or a PG-specific test (fasting plasma glucose or oral glucose tolerance test) should establish the diagnosis of diabetes. The recommendations are offered for consideration of the clinical community and interested associations and societies.

Population-based assessment of the level of care among adults with diabetes in the U.S.

OBJECTIVE—The purpose of this study was to examine possible factors associated with the increased risk of fractures observed with rosiglitazone in A Diabetes Outcome Progression Trial (ADOPT). RESEARCH DESIGN AND METHODS—Data from the 1,840 women and 2,511 men randomly assigned in ADOPT to rosiglitazone, metformin, or glyburide for a median of 4.0 years were examined with respect to time to first fracture, rates of occurrence, and sites of fractures. RESULTS—In men, fracture rates did not differ between treatment groups. In women, at least one fracture was reported with rosiglitazone in 60 patients (9.3% of patients, 2.74 per 100 patient-years), metformin in 30 patients (5.1%, 1.54 per 100 patient-years), and glyburide in 21 patients (3.5%, 1.29 per 100 patient-years). The cumulative incidence (95% CI) of fractures in women at 5 years was 15.1% (11.2–19.1) with rosiglitazone, 7.3% (4.4–10.1) with metformin, and 7.7% (3.7–11.7) with glyburide, representing hazard ratios (95% CI) of 1.81 (1.17–2.80) and 2.13 (1.30–3.51) for rosiglitazone compared with metformin and glyburide, respectively. The increase in fractures with rosiglitazone occurred in pre- and postmenopausal women, and fractures were seen predominantly in the lower and upper limbs. No particular risk factor underlying the increased fractures in female patients who received rosiglitazone therapy was identified. CONCLUSIONS—Further investigation into the risk factors and underlying pathophysiology for the increased fracture rate in women taking rosiglitazone is required to relate them to preclinical data and better understand the clinical implications of and possible interventions for these findings.

Comparison of Fasting and 2-Hour Glucose and HbA1c Levels for Diagnosing Diabetes: Diagnostic criteria and performance revisited

OBJECTIVE To analyze the health benefits and economics of treating NIDDM with the goal of normoglycemia. RESEARCH DESIGN AND METHODS Incidence-based simulation model of NIDDM was used. Hazard rates for complications were adjusted for glycemia using risk gradients from the Diabetes Control and Complications Trial. Treatment costs were estimated from national survey data and clinical trials. Incremental costs and benefits were expressed in present value dollars (3% discount rate). Life-years were adjusted for quality of life, yielding quality-adjusted life-years (QALYs). RESULTS Comprehensive treatment of NIDDM that maintains an HbA1c value of 7.2% is predicted to reduce the cumulative incidence of blindness, end-stage renal disease, and lower-extremity amputation by 72, 87, and 67%, respectively. Cardiovascular disease risk increased by 3% (no effect of treating glycemia is assumed). Life expectancy increased 1.39 years. The cost of treating hyperglycemia increased by almost twofold, which is partially offset by reductions in the cost of complications. The estimated incremental cost/QALY gained is

Managing preexisting diabetes for pregnancy: Summary of evidence and consensus recommendations for care

16,002. Treatment is more cost-effective for those with longer glycemic exposure (earlier onset of diabetes), minorities, and those with higher HbA1c under standard care. CONCLUSIONS The incremental effectiveness of treating NIDDM with the goal of normoglycemia is estimated to be ∼

Diabetes: a 21st century challenge

16,000/QALY gained, which is in the range of interventions that are generally considered cost-effective.