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Cost-effectiveness of rosiglitazone oral combination for the treatment of type 2 diabetes in Germany |
Shearer A T, Bagust A, Liebl A, Schoeffski O, Goertz A |
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Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology Several treatments for patients with Type 2 diabetes were examined. For normal-weight and overweight patients, the combination of metformin (MET) and sulfonylurea (SUL) was compared with rosiglitazone (ROS) plus either SUL or MET. In obese patients, MET monotherapy was compared with ROS+MET, while MET+SUL was compared with ROS+MET. ROS was given at a dose of 4 or 8 mg/day, MET at 850 mg/day and SUL at 3.5 mg/day.
Economic study type Cost-effectiveness analysis and cost-utility analysis.
Study population The study population comprised a hypothetical cohort of normal-weight, overweight and obese adult patients, aged 20 years or older, who were newly diagnosed with Type 2 diabetes.
Setting The setting was secondary care. The economic study was carried out in Germany.
Dates to which data relate The effectiveness data were derived from studies published between 2001 and 2006. Most of the resource use data and some cost data were derived from a database published in 2002. Other resources and costs were obtained from studies published in 2001 and 2002. The price year was 2001.
Source of effectiveness data The effectiveness evidence was derived from a synthesis of published studies.
Modelling The DiDACT is a long-term economic model of disease progression and health care resource consumption for individuals with Type 2 diabetes. The model consisted of a series of interconnected Markov models. The time horizon of the model was lifetime. Other details of the model were not provided.
Outcomes assessed in the review The outcomes estimated from the literature were:
the international age- and gender-specific incidence rates of diabetes,
the German population profile,
the transition probabilities across health states,
the prevalence of complications,
German age-, gender-, and cause-specific mortality rates,
German census population data,
treatment effectiveness, and
utility values.
Study designs and other criteria for inclusion in the review The primary studies do not appear to have been identified selectively and a review of the literature does not appear to have been carried out. The incidence and prevalence of diabetes complications were taken from the German arm of the pan-European study Cost of Diabetes in Europe - Type 2 (CODE-2), while other data came from administrative databases. However, details of the majority of the primary studies were not reported.
Sources searched to identify primary studies Criteria used to ensure the validity of primary studies Methods used to judge relevance and validity, and for extracting data Number of primary studies included Nine primary studies provided the clinical data.
Methods of combining primary studies The primary estimates do not appear to have been combined as each study was used to derive a series of clinical estimates.
Investigation of differences between primary studies Results of the review Clinical data used to populate the decision model were not reported.
Measure of benefits used in the economic analysis The summary benefit measures used were the life-years (LYs) and quality-adjusted life-years (QALYs). These were estimated using a modelling approach. The utility weights used to assess QALYs were obtained from a study that used the time trade-off method. No discounting was applied to the benefits.
Direct costs The analysis of the costs was conducted from the perspective of the sickness funds. The macro-categories of direct costs included were inpatient, ambulatory, rehabilitation, diabetes therapy and other medications. A detailed breakdown of the cost items was provided. The unit costs were listed but there was little information on the quantities of resources used. The costs were estimated from typical German sources and from some published studies. The resource use data were obtained from a representative sub-sample of 25.1 million hospital admissions and the CODE-2 study. Medication use and costs were derived from the International Marketing Services Health Disease database, and co-payments and discounts were taken into account. Discounting was relevant, owing to the long timeframe of the analysis, and an annual rate of 5% was applied. The price year was 2001. The costs derived from previous years were inflated to 2001 values using the German Consumer Price Index.
Statistical analysis of costs The costs were treated deterministically.
Indirect Costs The authors included the indirect costs associated with sickness leave longer than 42 days, as these costs are relevant from the perspective of sickness funds. Resource use and consumption were mainly obtained from the CODE-2. The unit costs and the quantities of resources used were presented separately. The price year was 2001. An annual discount rate of 5% was applied.
Sensitivity analysis Univariate sensitivity analyses were carried out to assess the robustness of the estimated cost-utility ratios to variations in key model drivers. For example, a therapy-switching threshold of haemoglobin A1c, discount rate, ROS cost, ROS efficacy and body mass index (BMI) at diagnosis.
Estimated benefits used in the economic analysis In a cohort of 1,000 normal-weight and overweight patients, the expected LYs gained were 140 with ROS+SUL over MET+SUL and 167 with ROS+MET over MET+SUL. The expected QALYs gained were, respectively, 214 (ROS+SUL over MET+SUL) and 286 (ROS+MET over MET+SUL).
In a cohort of 1,000 obese patients, the expected LYs gained were 188 with ROS+MET over MET+SUL and 177 with ROS+MET over MET alone. The expected QALYs gained were, respectively, 295 (ROS+MET over MET+SUL) and 346 (ROS+MET over MET alone).
Cost results In a cohort of 1,000 normal-weight and overweight patients, the additional discounted costs were EUR 4.25 million with ROS+SUL over MET+SUL and EUR 5.26 million with ROS+MET over MET+SUL.
In a cohort of 1,000 obese patients, the additional discounted costs were EUR 5.18 million with ROS+MET over MET+SUL, and EUR 3.00 million with ROS+MET over MET alone.
Synthesis of costs and benefits Incremental cost-effectiveness and cost-utility ratios were calculated to combine the costs and benefits.
In the cohort of normal-weight and overweight patients, the incremental cost per LY gained was EUR 30,357 with ROS+SUL over MET+SUL and EUR 31,499 with ROS+MET over MET+SUL. The incremental cost per QALY gained was EUR 19,836 with ROS+SUL over MET+SUL and EUR 18,425 with ROS+MET over MET+SUL.
In the cohort of obese patients, the incremental cost per LY gained was EUR 33,787 with ROS+MET over MET+SUL and EUR 22,004 with ROS+MET over MET alone. The incremental cost per QALY gained was EUR 17,523 with ROS+MET over MET+SUL and EUR 8,669 with ROS+MET over MET alone.
The sensitivity analysis showed that the base-case results were robust to variations in the therapy-switching threshold of haemoglobin A1c, alternative discount rates (although simultaneous use of a 5% discount rate for costs and benefits increased the estimated cost-effectiveness and cost-utility ratios to above the threshold of EUR 50,000 per LYs or QALYs gained in some circumstances), changes in ROS efficacy, and alternative BMIs. The cost per QALY was sensitive to variations in ROS costs in that a reduction in costs led to improved (i.e. lower) cost-utility ratios.
Authors' conclusions The cost-effectiveness ratios of rosiglitazone (ROS) in combination with other oral agents for the treatment of Type 2 diabetes in Germany fell below international thresholds for the choice of efficient health technologies.
CRD COMMENTARY - Selection of comparators The rationale for the selection of the comparators was clear as the new treatment (including ROS) was compared with conventional care, as recommended in Germany. Dosages were also reported. You should decide whether they are valid comparators in your own setting.
Validity of estimate of measure of effectiveness The effectiveness evidence was derived from published sources. However, it was not stated whether a systematic review of the literature was undertaken, and the primary studies appear to have been identified selectively. In general, few details of the primary studies were provided. Thus, it was difficult to assess the validity of the primary sources. Further, the issue of the homogeneity of the studies was not addressed and sensitivity analyses were not performed on the clinical data. Some country-specific data were used. However, the majority of the clinical data were not reported.
Validity of estimate of measure of benefit QALYs and LYs are the most appropriate benefit measure because they capture the impact of the intervention on quality of care and survival, which are the most relevant dimensions of health for patients with Type 2 diabetes. Utility was derived from the literature and the instrument used to assess the utility weights was reported. The use of QALYs permits comparisons with the benefits of other health care interventions.
Validity of estimate of costs The costs included were consistent with the perspective adopted in the study. A detailed breakdown of the cost items was provided and the unit costs were presented for most items. However, fewer details on resource consumption were given, which limits the possibility of replicating the cost analysis in other settings. The cost estimates were specific to the study setting and sensitivity analyses were carried out only on the drug costs. Caution will be required when extrapolating the analysis to other settings, owing to the peculiarities of the German health care system. The source of the data was given for all items. The price year was reported, which will facilitate reflation exercises in other time periods. Most of the data on costs and resource consumption came from a valid European database; this represents a strength of the economic analysis.
Other issues The authors reported the cost-effectiveness estimates obtained in a recently published study and stated that these figures were comparable to those achieved in the current study. The issue of the generalisability of the study results to other settings was not addressed and few sensitivity analyses were performed. This reduces the external validity of the analysis. In general, the issue of uncertainty and variability around the model parameters was not addressed satisfactorily, given that only one-way sensitivity analyses were performed. The authors also noted that the effectiveness of ROS was based exclusively on insulin sensitisation, thus the base-case results were conservative. Other conservative assumptions were also made.
Implications of the study The study results support the use of ROS for the treatment of patients with Type 2 diabetes.
Source of funding Supported by GlaxoSmithKline.
Bibliographic details Shearer A T, Bagust A, Liebl A, Schoeffski O, Goertz A. Cost-effectiveness of rosiglitazone oral combination for the treatment of type 2 diabetes in Germany. PharmacoEconomics 2006; 24(Supplement 1): 35-48 Other publications of related interest Bagust A, Hopkinson PK, Maier W, et al. An economic model of the long-term health care burden of type 2 diabetes. Diabetologia 2001;44:2140-55.
Beale S, Bagust A, Shearer AT, et al. Cost-effectiveness of rosiglitazone oral combination for the treatment of type 2 diabetes in UK. Pharmacoeconomics 2006;24 Suppl 1:21-34.
Nesser K, Lubben G, Siebert U, et al. Cost-effectiveness of combination therapy with pioglitazone for type 2 diabetes mellitus from a German statutory healthcare perspective. Pharmacoeconomics 2004;22:321-41.
Indexing Status Subject indexing assigned by NLM MeSH Administration, Oral; Adult; Aged; Cost-Benefit Analysis; Diabetes Complications; Diabetes Mellitus, Type 2 /drug therapy /economics /rehabilitation; Drug Therapy, Combination; Economics, Pharmaceutical; Female; Germany; Hemoglobin A, Glycosylated /drug effects; Hospitalization /economics; Humans; Hypoglycemic Agents /administration & Insulin /economics /therapeutic use; Male; Metformin /administration & Middle Aged; Models, Economic; Obesity /complications; Quality-Adjusted Life Years; Thiazolidinediones /administration & dosage /economics /therapeutic use; dosage /economics /therapeutic use; dosage /therapeutic use AccessionNumber 22006008099 Date bibliographic record published 31/08/2006 Date abstract record published 31/08/2006 |
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