|Cost effectiveness of an intensive blood glucose control policy in patients with type 2 diabetes: economic analysis alongside randomised controlled trial (UKPDS 41)
|Gray A, Raikou M, McGuire A, Fenn P, Stevens R, Cull C, Stratton I, Adler A, Holman R, Turner R
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.
Intensive blood glucose control policy in patients with type 2 diabetes.
Economic study type
Patients with type 2 diabetes.
Hospital. The economic study was carried out in the UK.
Dates to which data relate
Effectiveness and resource use data were collected from a trial published in 1998. Additional resource use data were derived from a questionnaire distributed between January 1996 and September 1997. Cost data were collected from 1996-1998 sources. The price year was 1997.
Source of effectiveness data
Effectiveness data were derived from a single study.
Link between effectiveness and cost data
The costing was undertaken on the same patient sample as that used in the effectiveness analysis and was carried out prospectively alongside the effectiveness analysis.
3,867 patients were randomised to conventional management (n=1,138), and to intensive management with insulin (n=1,156) or sulphonylureas (n=1,573). No power calculations or exclusion criteria were reported.
This was a prospective randomised controlled trial carried out at 23 centres. The median follow-up period to death, the last known date of survival or end of trial, was 10 years. Loss to follow-up was not reported.
Analysis of effectiveness
The analysis of the clinical study was based on intention to treat. Primary health outcomes used were death or the development of diabetic complications. The authors did not report whether groups were comparable at analysis.
Intensive blood glucose control significantly reduced (p=0.029) the risk of any diabetes related endpoint by 12% but did not significantly reduce diabetes related deaths or all cause mortality.
Intensive blood glucose control increased the time free of complications.
Simulation from a parametric model was used to estimate time from study closure to first event. Bootstrap confidence intervals were calculated for all simulation results based on 5,000 non-parametric bootstrap iterations. The simulation model was a two-fold competing risk model. Multiple regression was used to estimate non-hospital resource use adjusted for significant variables.
Measure of benefits used in the economic analysis
The time to first event was used as the measure of benefit. Benefits were discounted at an annual rate of 6%.
Direct costs were discounted at an annual rate of 6%. Quantities and costs were reported separately. Direct costs covered conventional and intensive treatments, visits to diabetic clinics and tests, and treatment of diabetic complications, including inpatient stays and outpatient health care. The quantity/cost boundary adopted was that of the health service. The estimation of quantities and costs was based on actual data. Unit costs were obtained from national statistics and from centres participating in the trial. The price year was 1997.
Statistical analysis of costs
For all costs reported in the paper parametric confidence intervals for cost differences were compared with bootstrap confidence intervals and were found to be robust - the authors therefore reported parametric confidence intervals. Standard deviations were reported for all costs and 95% CIs were reported for all cost differences.
Sensitivity analyses were performed to examine the effect of variations in the cost of visits and blood glucose test schedules.
Estimated benefits used in the economic analysis
The time to first event was 14.29 years in the conventional group and 14.89 years in the intensive group, a difference of 0.6 (0.12 - 1.1) years. Discounted at 6%, the time to first event was 8.88 years in the conventional group and 9.17 years in the intensive group, a difference of 0.29 (0.06-0.53) years.
Routine treatment costs were 3,655 per patient in the conventional group and 4,350 in the intensive group, a difference of 695 (95% CI: 555 - 836). The cost of all hospital admissions was 4,266 in the conventional group and 3,494 in the intensive group. Costs per patient amounted to 9,869 in the conventional group and 9,608 in the intensive group. Discounted at 6%, costs per patient amounted to 7,170 in the conventional group and 6,958 in the intensive group. When trial visits and tests were replaced by those likely in clinical practice, the cost per patient was 7,871 in the conventional group and 8,349 in the intensive group. Discounted at 6%, costs per patient were 5,689 in the conventional group and 6,027 in the intensive group.
Synthesis of costs and benefits
Discounting both costs and benefits at 6% and using trial data, the cost per event-free year gained was 1,166 (-692 to 8,819). This ratio varied between 572 and 2,155 in sensitivity analysis.
Intensive blood glucose control in patients with type 2 diabetes significantly increased treatment costs but substantially reduced the cost of complications and increased the time free of complications.
CRD COMMENTARY - Selection of comparators
The choice of comparator was justified in that it represented current practice. You, as a user of the database, should decide if these health technologies are relevant to your setting.
Validity of estimate of measure of benefit
The analysis was based on a randomised controlled trial, which was appropriate for the study question. The study sample was representative of the study population. The authors did not report whether patient groups were comparable at analysis. Appropriate statistical techniques, including simulation and bootstrapping were used to estimate the time to first event for patients with no observed events. The estimation of benefits was obtained directly from the effectiveness analysis.
Validity of estimate of costs
All categories of cost relevant to the perspective adopted were included in the analysis. However, no indirect costs such as those related to productivity loss were considered. Costs and quantities were reported separately. No sensitivity analysis was carried out on quantities. A sensitivity analysis was performed on the costs of visits. The price year was reported.
The authors addressed the issue of generalisability to other settings, but were unable to make comparisons with other studies as, at the time the resesarch was conducted no comparable studies had been published. The authors did not present their results selectively. The study enrolled patients with type 2 diabetes and this was reflected in the authors' conclusions.
Implications of the study
Further evaluations will be needed to examine different ways in which an intensive blood glucose control policy can be translated into standard practice and the role of new drugs. Future studies should also cast further light on the non-hospital costs of diabetic complications.
Source of funding
Funding from Glaxo Wellcome, SmithKline Beecham, Pfizer, Zeneca, Pharmacia Upjohn, Novo Nordisk, Bayer, Roche and UK Department of Health. Richard Stevens is supported by a Wellcome Trust fellowship (grant No 054470/Z/98/Z/DG/NOS/FH). The main study was supported by grants from the UK Medical Research Council, British Diabetic Association, UK Department of Health, US National Eye Institute and National Institute of Diabetes, Digestive and Kidney Disease in the National Institutes of Health, British Heart Foundation, Novo Nordisk, Bayer, Bristol-Myers Squibb, Hoechst, Lilly, Lipha and Farmitalia Carol Erba.
Gray A, Raikou M, McGuire A, Fenn P, Stevens R, Cull C, Stratton I, Adler A, Holman R, Turner R. Cost effectiveness of an intensive blood glucose control policy in patients with type 2 diabetes: economic analysis alongside randomised controlled trial (UKPDS 41) BMJ 2000; 320: 1373-1378
Other publications of related interest
The Diabetes Control and Complications Trial Research Group (DCCT). Lifetime benefits and costs of intensive therapy as practised in the diabetes control and complications trial. JAMA 1996;276:1409-1415.
Subject indexing assigned by NLM
Adult; Aged; Blood Glucose /analysis; Blood Glucose Self-Monitoring /economics; Cost-Benefit Analysis; Costs and Cost Analysis; Diabetes Mellitus, Type 2 /blood /complications /drug therapy; Diabetic Nephropathies /economics; Diabetic Retinopathy /economics; Disease-Free Survival; Follow-Up Studies; Hospitalization /economics; Humans; Middle Aged
Date bibliographic record published
Date abstract record published