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The cost-effectiveness of a cardiovascular multiple-risk-factor intervention programme in treated hypertensive men |
Johannesson M, Agewall S, Hartford M, Hedner T, Fagerberg B |
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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 A multifactor intervention programme for hypertensive men, ie advice given to individuals, and group meetings based on nutritional advice and behavioural treatment principles, plus drug therapy if necessary.
Economic study type Cost-effectiveness analysis
Study population Males, aged 50-72 (mean 66.4 years), with treated hypertension and at least one of: serum cholesterol > or = 6.5 mmol L-1, and smoking, and diabetes mellitus.
Setting Outpatient clinic. The economic study was carried out in Sweden.
Dates to which data relate 1991 prices were used. Effectiveness and resource data were extracted from a study described in 1992-1993 publications.
Source of effectiveness data Link between effectiveness and cost data Costing was undertaken on the same patient sample used in the effectiveness data. It is not clear if cost data were collected prospectively or retrospectively.
Study sample 508 patients randomised between conventional treatment and a multifactorial risk factor modification programme; no power calculations were reported. Numbers in each arm were not explicitly reported; it seems that 253 patients were included in the intervention group.
Study design Randomized (parallel group), single centre study. Follow-up at 1 year and 3 years. Loss to follow-up not specified.
Analysis of effectiveness It was not specified if the analysis was based on "intention to treat" or "treatment completers". Primary health outcomes were changes in major cardiovascular risk factors (diastolic blood pressure, total cholesterol, smoking, diabetes) and in CHD and stroke events.
Effectiveness results After 3 years of follow-up, the change in total cholesterol and smoking was statistically significant at the 5% level, whereas the change in diastolic blood pressure was statistically significant at 1 year but not at 3 year follow-up. The observed reduction of CHD and stroke was 11% and 70% respectively.
The means of the 1-year and 3-year values of the cardiovascular risk factors without intervention and with intervention were respectively: for diastolic blood pressure 88.4 and 87.4; total cholesterol (mmol) 6.4 and 6.0; smoking (% of smokers) 26% and 20%; diabetes 22% in both cases.
Modelling A model was used to determine final costs and benefits
Measure of benefits used in the economic analysis Life-years gained, derived using a model.
Direct costs Generally, costs and quantities were reported separately. Costs were discounted at 5%, and were health service costs of the intervention, plus travel costs to patients, minus saved morbidity costs due to acute myocardial infarction, select myocardial infarction, angina and stroke avoided. Health service costs included: nurse and physician visits (costed using another study for the cost figure); dietitian visits; educational materials and cost of meetings (costed in the effectiveness study); cost of lipid-lowering drugs (based on doses and drugs used in the effectiveness study, and on Swedish retail prices). Travel costs were calculated using data from the effectiveness study. Saved morbidity costs were extracted from the literature. Costs were calculated in 1991 prices.
Indirect Costs Costs were discounted at 5%. Costs and quantities were reported separately. Time loss for patients in hours calculated from another study, assumed not to have a loss-of-income cost because the average age was 66 years, hence valued at 35% of the gross wage rate. Relatives' time: estimated and valued on the same basis.
Sensitivity analysis A number of one-way simple sensitivity analyses were carried out. varying assumptions of health impacts, costs to patients of meeting attendance, quality of life effects, and discount rates, sex, age, mortality rates were made.
Estimated benefits used in the economic analysis Incremental life-years gained were .0944, observed in the trial and discounted at 5%.
Cost results Incremental cost per patient was SEK 399. Cost of normal treatment was assumed to be common to both intervention and non-intervention arms.
Synthesis of costs and benefits Costs (discounted at 5%) per life year gained (discounted at 5%), in an incremental analysis. In three estimations based on the changes in risk factors, the cost per life-year gained varied between SEK 62,000 and SEK 163,000. In the estimation based on the outcomes observed in the trial, the ratio was about SEK 4,000. The results were sensitive to a number of parameters in particular sex, quality of life during treatment, risk factor changes and risk reduction.
Authors' conclusions Under every reasonable set of assumptions, the intervention programme is cost-effective in the patient population studied in the trial.
CRD Commentary This is a detailed and sophisticated study, which examines different values of most of the variables affecting the cost-effectiveness outcome, and rightly emphasises the need for caution in the interpretation of the results. The number of sensitivity analyses is justified by the possible different mixes in the risk factors which might be found in a particular population. However, final results are very sensitive to a number of relevant parameters, and the authors provided justifications about their range of variations, referring to cut-off values of published guidelines.
The usefulness of the conclusions depend on the generality of the intervention's precise definition. Also, the valuation of patient and relative time might have been more careful e.g. if the retirement age is 65, it seems inappropriate to assume that the whole group is retired because its average age is 66. If relatives were younger, on the average, then their time would have been more valuable.
Source of funding National Corporation of Swedish Pharmacies; Swedish Medical Research Council; Swedish Heart and Lung Foundation; Swedish Hypertension Society.
Bibliographic details Johannesson M, Agewall S, Hartford M, Hedner T, Fagerberg B. The cost-effectiveness of a cardiovascular multiple-risk-factor intervention programme in treated hypertensive men. Journal of Internal Medicine 1995; 237(1): 19-26 Other publications of related interest Comment in: Journal of Internal Medicine 1995;237(1):1-3.
Indexing Status Subject indexing assigned by NLM MeSH Aged; Antihypertensive Agents /economics; Behavior Therapy /economics; Cost-Benefit Analysis; Humans; Hypertension /drug therapy /economics /etiology /therapy; Male; Middle Aged; Outpatient Clinics, Hospital /economics; Patient Education as Topic /economics; Referral and Consultation /economics; Risk Factors; Sensitivity and Specificity; Sweden; Value of Life AccessionNumber 21995000202 Date bibliographic record published 25/03/1996 Date abstract record published 25/03/1996 |
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