Cost-Effectiveness of Drug Therapy for Diabetes Mellitus – A Systematic Review Yan-Jun Zhang, BS Pharmacy, MMS Pharmacology; Rashmi R. Nair, Ph.D.; Jinender Kumar, B.Pharm., D.M.M. Department of Pharmacy Health Care Administration, College of Pharmacy, University of Toledo According to the fact sheet issued by the Centers for Disease Control and Prevention (CDC), in the year 2005, 20.8 million people are diabetics in the United States which accounted for 7% of the population of the US. Estimated diabetes costs in the US were $132 billion in 2002, of which direct medical expenditures were $92 billion. The huge economic burden on healthcare necessitates researchers and policy-makers to conduct cost studies in order to reduce it. To compare and contrast the cost-effectiveness of various diabetes medications, we conducted the systematic review of cost-effectiveness of antidiabetic drugs including insulin. Background and Objectives Methods A literature search using PubMed, OhioLINK, SciFinder, EMBASE and Cochrane library was conducted for cost-effectiveness studies on hypoglycemic agents and insulin, combined with reference lists of literatures and manual search of the journals Pharmacoeconomics and Current Medical Research and Opinion . The key terms used for literature search were “diabetes”, and “cost-effectiveness, cost-benefit, costs and cost analysis, economics, pharmaceutical economics”. Two reviewers independently assessed and identified the relevant literatures using the following inclusion and exclusion criteria. Initial search resulted in 1402 abstracts. After applying the inclusion/exclusion criteria, 13 studies were identified from UK, Canada, USA, and Germany on either type 1 or type 2 diabetes mellitus. There is no cost-effectiveness study on gestational diabetes. Except part of one study reported within-trial cost-effectiveness, all the studies are modeling from the short-term RCTs. The median sample size was 638 patients; the median duration of trials was 39 weeks. Most studies demonstrated overall positive effects in economic outcomes and found that interventions improved the cost-effectiveness and health care utilization over the comparators from their individual perspectives. The studies focused on some relatively new drugs which were approved to market in recent years, such as insulin glargine, insulin detemir, exenatide and rosiglitazone etc. These new antidiabetic drugs and insulin analogues showed their cost-effectiveness. The more detailed information are displayed in the following tables. Results There has been no cost-effectiveness review of pharmacotherapy for diabetes. However, there is growing evidence that these drug interventions may promote diabetic health with better economic outcomes. There are few within-trial cost-effectiveness studies for diabetes drug therapy. Future RCTs should take within-trial economic evaluation into account. There are some benefits of pharmacoeconomic modeling studies. The uncertainties and assumptions in model formalization process are made explicit and transparent. “To estimate costs and outcomes, existing data is frequently insufficient to allow optimal healthcare decision-making. Good modeling practice incorporates the best available evidence from all possible sources into a set of explicit parameters.” “Mathematical modeling allows a rational and scientific approach to overcoming the inherent limitations of RCTs, using the best available evidence.”  However, “modeling study practical value is currently limited by insufficient standardization, meager documentation of practices and policies, no systematic quality surveillance, and a low level of acceptance by regulatory agencies and end users.”  The results of this study should be interpreted with several limitations in mind. First, the heterogeneity of the studies including different countries and regions, different perspectives and diverse medications, weakened any general inferences. Second, only articles written in English language and conducted in RCTs were reviewed. However, double reviews were conducted to minimize errors and increase accuracy in data abstraction. Future review should involve such databases as Science Citation Index (SCI), International Pharmaceutical Abstracts (IPA), Office of Health Economics Health Economic Evaluation Database (OHE-HEED), Health Technology Assessment (HTA) database, and UK National Health Service Economic Evaluations Database (NHS-EED). Discussion and Conclusions Inclusion and Exclusion Criteria Eligible studies were those focused on cost-effectiveness of antidiabetic drugs based on randomized controlled trials (RCTs), and published in English before January 2008. The qualities of RCTs and economic evaluation were assessed using the Cochrane standard  and British Medical Journal checklist  respectively. Studies on preventive interventions of diabetes and pharmacoeconomics of diabetes-related complications were excluded. Abbreviations: CORE, Center for Outcomes Research diabetes model; DCCT, Diabetes Control and Complications Trial; DES, Discrete Event Simulation; DiDACT, Diabetes Decision Analysis of Cost – type 2; ICER, Incremental Cost-Effectiveness Ratio; INITIATE, Initiate Insulin by Aggressive Titration and Education; NHS, (UK) National Health Service; NPH, Neutral Protamine Hagedorn; PROactive, PROspective pioglitAzone Clinical Trial In macroVascular Events; QALY, Quality-Adjusted Life Year; RCT, Randomized Controlled Trial; UKPDS, UK Prospective Diabetes Study. Table: Characteristics of the Included Studies Table: Characteristics of the Included Studies (continued)
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References 2001 RCT sickness funds Germany Rosiglitazone + other oral agents vs. other + other oral agents Type 2 Shearer AT et al  2004 INITIATE clinical trial third-party payer US Insulin aspart 30 vs. insulin glargine Type 2 Ray JA et al  2005 PROactive Study health-care payer (NHS) UK Pioglitazone + existing regimens vs. placebo + existing regimens Type 2 Valentine WJ et al  2005 pooled data from RCTs including DCCT NHS UK Insulin glargine vs. NPH insulin Type 2 McEvan P et al  2004 INITIATE clinical trial NHS UK Insulin aspart 30/70 vs. insulin glargine Type 2 Valentine WJ et al  2004 RCT NHS UK Exenatide vs. insulin glargine Type 2 Ray JA et al  2003 RCT NHS UK Rosiglitazone + metformin vs. sulfonylurea + metformin Type 2 Beale S et al  2004/5 RCT NHS UK Pioglitazone + metformin vs. rosiglitazone + metformin Type 2 Tilden DP et al  2005 RCT including UKPDS and DCCT Canadian public payer Canada Insulin glargine vs. NPH insulin Type 1 and type 2 Grima DT et al  2005 RCT Medicare US Insulin detemir vs. NPH; Insulin detemir vs. glargine Type 1 Valentine WJ et al  2005 pooled data from RCTs including DCCT NHS UK Insulin glargine vs. NPH insulin Type 1 McEvan P et al  2004 RCT by Hermansen et al. NHS UK Insulin detemir + aspart vs. NPH + human soluble insulin Type 1 Palmer AJ et al  2003 A meta-analysis of results from four clinical trials NHS UK Insulin detemir vs. NPH insulin Type 1 Palmer AJ et al  Year of Costing Clinical Data Perspective Country Medication Interventions Types of diabetes Study £6951/QALY CORE 3.5 35 Valentine WJ et al  $46533 CORE 3.0 35 Ray JA et al  £5396/QALY (within-trial); £4060/QALY (modeling) CORE (modified version) 3.5 Modeling: 35 Valentine WJ et al  £10027 to £13921 DES 3.5 Maximum: 40 McEvan P et al  £22420/QALY (100% exenatide price of US) CORE 3.5 35 Ray JA et al  £16700 (obese cohort); £11600 (overweight cohort) DiDACT 3.5 lifetime Beale S et al  Pioglitazone dominate (0.0384 additional QALYs, costs lower £714) Self-developed 3.5 lifetime Tilden DP et al  Below international “willingness to pay” thresholds DiDACT 5 (health outcomes not discounted) lifetime Shearer AT et al  $Can20799 (type 1); $Can8618 (type 2) Self-developed 5 36 Grima DT et al  100% probability below $50000 (vs. NPH); 80% probability below $50000 (vs. glargine); CORE 3.0 35 Valentine WJ et al  £2695 to £10943 discrete event simulation (DES) 3.5 over a maximum of 40 years McEvan P et al  £2500 CORE 3.5 Over patient lifetimes Palmer AJ et al  £19285 CORE 3.5 Over patient lifetimes Palmer AJ et al  ICER (/QALY) Model Discount Rate (%) Time Horizon (years) Study