|
Modelling and costing the consequences of using an ACE inhibitor to slow the progression of renal failure in type I diabetic patients |
Hendry B M, Viberti G C, Hummel S, Bagust A, Piercy J |
|
|
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 Using an angiotensin-converting enzyme (ACE)inhibitor, captopril (25 mg, 3 times a day) to slow progression of renal failure in diabetic patients.
Economic study type Cost-effectiveness analysis.
Study population Patients (18-49 years old) with insulin-dependent diabetes mellitus (IDDM) starting before the age of 30 and with a history of at least 7 years.
Setting Hospital. The economic study was carried out in London, UK.
Dates to which data relate The effectiveness data were taken mainly from a paper published in 1993. The progression rate to ESRF and death was extracted from another study (which was based on the 1993 paper) published in 1994. The dates relating to some other clinical probabilities, which were estimated based on the literature, were not given. Resource and cost data were mainly related to 1995. The price year was not clearly reported.
Source of effectiveness data Estimates of the risk of a doubling of the serum creatinine concentration were based on a single randomised study (the DNCSG study). Progression rates to ESRF were extracted from another study whose estimation was based on the data from the DNCSG study. The estimation of other clinical probabilities required in the model was based on assumptions or on literature review. The estimation of the life years saved was based on the model.
Link between effectiveness and cost data The costing was retrospectively performed on a different sample (a cohort of 1,000 hypothetical patients).
Study sample The DNCSG study sample consisted of 409 patients. No more details were given.
Study design A multicentre, placebo-controlled randomised trial. The duration of the trial was 4 years. No more details were given.
Analysis of effectiveness The clinical outcomes reported were the risk of a doubling of the serum creatinine concentration, kidney-protecting effect and side effects. No more details were given.
Effectiveness results The risk reduction associated with the use of the intervention was 48%. It was reported that the intervention had "a beneficial kidney-protecting effect and few serious side effects".
Clinical conclusions AEC inhibitor therapy should be used in normotensive and hypertensive patients with diabetes and clinically evident nephropathy.
Modelling An economic model was employed to estimate the benefits (in terms of survival and the requirement for kidney transplantation) and costs associated with ACE inhibitor treatment in IDDM patients with nephropathy.
Outcomes assessed in the review Long-term survival rates and, probabilities related to comorbid conditions, the prevalence rates of the three most common modes of dialysis in UK, percentage of patients receiving a kidney transplant over a period of 2 and half years, and the percentage of patients waiting for a transplant who die annually were among the outcomes assessed in the review.
Study designs and other criteria for inclusion in the review 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 Methods of combining primary studies Investigation of differences between primary studies Results of the review Long-term survival rates and probabilities related to comorbid conditions were not reported. The prevalence rates of the three most common modes of dialysis in UK were 35% for hospital, 5% for home, and 60% for continuous ambulatory peritoneal dialysis (CAPD). The percentage of patients receiving a kidney transplant over a period of 2 and half years and the percentage of patients waiting for a transplant who die annually were 35% and 15%, respectively.
Methods used to derive estimates of effectiveness Assumptions relating to effectiveness were made.
Estimates of effectiveness and key assumptions The percentage of patients developing ESRF who die because of not being treated as a result major complications was assumed to be 10%. It was assumed that the transplant assessment may result in an echocardiogram (90%), cardiac consultation (30%), and cardiac catheterization (15%). Only 16% of first transplants fail.
Measure of benefits used in the economic analysis Life years saved was the main benefit measure in the study.
Direct costs Costs were discounted. The resource quantities were not reported separately from the prices. Costs for procedures and other hospital treatments, drug costs, costs of GP care, and costs of cardiology treatments were included in the analysis. The quantity/cost boundary adopted was the NHS. Cost data were obtained from hospitals and published NHS reports. The date to which the price data referred was not stated.
Sensitivity analysis One-way and multi-way sensitivity analyses were carried out on the rates of progression to ESRF and death, rate of risk reduction and the costs associated with the procedures and treatment for ESRF.
Estimated benefits used in the economic analysis The total life years saved due to the use of the intervention over four years for a cohort of 1,000 patients was 195.
Cost results The discount rate was 6%. The discounted cost saving per patient of the ACE inhibitor treatment for a cohort of 1,000 patients was estimated to be 935 over 4 years.
Synthesis of costs and benefits A synthesis of the estimated benefits and costs was provided by calculating the cost per life year saved. The cost-effectiveness ratio was not calculated for the baseline since the intervention was shown to be the dominant strategy, but the ratio for the worst case, when the risk reduction was assumed to be 18%, was reported to be 1,360. The results were reported to be robust to the alteration in the costs of ESRF treatment.
Authors' conclusions Prophylactic treatment with ACE inhibitors was predicted to provide substantial increases in life expectancy and reduction in the incidence of end-stage renal failure (ESRF) while also providing significant economic savings.
CRD COMMENTARY - Selection of comparators The reason for the choice of comparator is clear.
Validity of estimate of measure of benefit The estimate of measure of benefit used in the economic analysis is likely to be internally valid.
Validity of estimate of costs Resource quantities were not reported separately from the prices and adequate details of methods of quantity/cost estimation were not given. Indirect costs were not included.
Other issues The authors' conclusions were justified, given the uncertainties in the data. The issue of generalisability to other settings was addressed, appropriate comparisons were made with other studies and the results were not presented selectively.
Source of funding Funded by an educational grant from Bristol-Myers Squibb Pharmaceuticals.
Bibliographic details Hendry B M, Viberti G C, Hummel S, Bagust A, Piercy J. Modelling and costing the consequences of using an ACE inhibitor to slow the progression of renal failure in type I diabetic patients. QJM 1997; 90(4): 277-282 Indexing Status Subject indexing assigned by NLM MeSH Adolescent; Adult; Aged; Angiotensin-Converting Enzyme Inhibitors /economics /therapeutic use; Captopril /economics /therapeutic use; Cohort Studies; Diabetes Mellitus, Type 1 /complications /economics; Diabetic Nephropathies /drug therapy; Disease Progression; England; Health Care Costs /statistics & Humans; Kidney Failure, Chronic /economics /etiology /prevention & Middle Aged; Models, Econometric; Sensitivity and Specificity; control; numerical data AccessionNumber 21997000623 Date bibliographic record published 31/03/1999 Date abstract record published 31/03/1999 |
|
|
|