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An economic evaluation of the JNC hypertension guidelines using data from a randomized controlled trial |
Ramsey S D, Neil N, Sullivan S D, Perfetto E |
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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 Four alternative drugs (beta-blocker, diuretic, calcium channel antagonist, angiotensin converting enzyme (ACE) inhibitor), either as a single agent or combination therapy, were compared to decide what anti-hypertensive agent should be recommended for initial therapy as part of a treatment guideline.
Economic study type Cost-effectiveness analysis.
Study population The study evaluated treatment and treatment guidelines for a population of uncomplicated, adult hypertensive patients, who had no contraindications to any one class of hypertensive agents and for whom hypertension control was the goal of therapy.
Setting The setting was primary care. The economic study was carried out in the USA.
Dates to which data relate Effectiveness evidence was taken from a study published in 1993. Resource use and prices were taken from data published in 1995.
Source of effectiveness data Effectiveness data were derived from a review/synthesis of the literature.
Modelling The study used a Markov model in order to account for multiple and repeated points of chance through time.
Outcomes assessed in the review The input parameters for the Markov model were not reported explicitly but the model appeared to use: probability of switching to another agent due to inadequate control; probability hypertension control is achieved; probability of experiencing intolerable side effects; probability of switching to another agent due to adverse lipid levels.
Study designs and other criteria for inclusion in the review The model used the results of one large randomised controlled trial to retrieve clinical efficacy data. The authors reported that other literature was used, but these other sources were not identified. No inclusion or exclusion criteria were 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 One primary study was included in the review as the source of effectiveness evidence.
Methods of combining primary studies Investigation of differences between primary studies Estimates of effectiveness and key assumptions Assumptions, in accordance with the JNC guidelines, were that 2% of patients on chlorthalidone and 1% on acebutolol would need to be switched due to increased lipid levels.
Measure of benefits used in the economic analysis The authors reported that benefits were measured in terms of the proportion of patients on each therapy with controlled hypertension at the end of the selected periods of observation (years 1, 3 and 5).
Direct costs Direct costs for the primary care health service were included in the model and these were: cost to achieve control after starting treatment; cost of maintenance therapy once control was achieved. Drug costs included the cost of each agent plus a dispensing fee. Non-drug costs include the cost of baseline assessment, routine monitoring and follow-up (office visits and laboratory testing), and for treatment failures, the cost of switching therapeutic classes. The costs of treating rare serious adverse events and long-term major disease endpoints (stroke, myocardial infarction) were not included in the analysis. Quantities and costs were not analysed separately. The estimation of the costs was derived from actual data. Drug costs were based on the 1995 average wholesale price list and non-drug costs were based on reimbursement schedules from a large managed care organisation (charges). Discounting was carried out on costs beyond the first year at a 3% annual discount rate.
Statistical analysis of costs No statistical tests were carried out.
Indirect Costs No indirect costs were included in the model because they were not appropriate to the study perspective.
Currency US dollars ($). No conversion rate was reported.
Sensitivity analysis A one-way sensitivity analysis tested the effect of modifying the values for all the input parameters for the model. Two-way sensitivity analyses were performed on the drug cost and efficacy parameters.
Estimated benefits used in the economic analysis Only the estimated benefits from the first-year of treatment with monotherapy were reported and these were: 77.8% effectiveness for acebutolol; 82.5% effectiveness for amlodipine; 68.1% effectiveness for enalapril and 67.5% effectiveness for chlorthalidone.
Cost results The total expected costs for patients who achieved control on initial therapeutic agent for the first year from the start of treatment were: $920 for acebutolol; $946 for amlodipine; $948 for enalapril and $641 for chlorthalidone.
The total expected costs for patients who achieve control on initial therapeutic agent for the third year from the start of treatment were: $2,080 for acebutolol; $2,175 for amlodipine; $2,154 for enalapril and $1,248 for chlorthalidone.
The total expected costs for patients who achieve control on initial therapeutic agent for the fifth year from the start of treatment were: $3,173 for acebutolol; $3,334 for amlodipine; $3,292 for enalapril and $1,821 for chlorthalidone.
Synthesis of costs and benefits The authors did not report any synthesis of costs and benefits. The authors detailed the impact of changing the cost and efficacy variables, and excluding the discount rate, in the one-way sensitivity analysis. The two-way sensitivity analysis showed that the efficacy required to maintain a constant cost of care rose substantially for modest increases in drug price.
Authors' conclusions The authors' concluded that, by following JNC guidelines, a slightly higher percentage of patients would achieve hypertension control with a calcium channel blocker (amlodipine) but at a substantially higher cost than with a generic diuretic (chlorthalidone).
CRD COMMENTARY - Selection of comparators This study attempted to evaluate the economic impact of the JNC hypertension guidelines using a Markov model that included four main approaches to the management of hypertension. The authors' acknowledged that the drugs used in the TOMHS study and this model were neither the most common nor the least costly agents in each anti-hypertensive class. You, as a user of this database should consider whether these treatment options reflect the current approach to clinical practice in your own setting before generalising the results.
Validity of estimate of measure of effectiveness This Markov model used efficacy and safety data from one published study. The authors did not report the search strategy or the reason for only using this one study. Furthermore, they did not report whether they reviewed the included study for quality in terms of study design. Thus, the reader cannot be sure whether the point estimates used in the baseline analysis were taken from a good quality published study. Systematic searches of literature sources should be undertaken to ensure that the selection of studies included in the review is unbiased and as comprehensive as possible. Finally, the authors' did not report any details regarding the patient population undergoing treatment represented by the model. It would have been informative to know whether particular patient characteristics, such as age, gender and duration of poor blood pressure control, could affect response to the treatment options under evaluation.
Validity of estimate of measure of benefit This model used a clinical end-point, control of hypertension, as the outcome measure to evaluate the benefits of each anti-hypertensive agent. This clinical-endpoint is a proxy outcome measure. Furthermore, it is not certain that there is a clear relationship between the control of hypertension and a positive impact on patients' health gain. In some instances, anti-hypertensive agents can cause a negative impact on patients' well being as a result of side effects. An outcome measure that valued the effect on patients' quality-of-life may have been more appropriate to quantify the benefits of each anti-hypertensive agent.
Validity of estimate of costs The model included estimates of non-drug costs that were based on HMO charges rather than prices. These cost estimates may be relevant to the US setting but the use of charge rather than price data mean that the results cannot be directly generalised to the UK health care setting. A 3% discount rate was used for costs which is lower than that usually recommended for use in the UK setting (6%). Applying a 6% discount rate on future costs would have decreased the expected costs for the third and fifth year for each treatment strategy. The authors did not report the results of combining the costs and benefits for each strategy as an incremental cost-effectiveness ratio. This would have provided the reader with useful information regarding the additional costs and for a unit change in percentage effectiveness for each anti-hypertensive.
Implications of the study The authors' suggest that diuretics and beta-blockers, which have been recommended as initial monotherapy for patients with hypertension on the basis of clinical evidence, are also the most attractive options from an economic standpoint. Drug costs are the largest proportion of the overall cost of managing hypertension, and the total cost of anti-hypertensive care is most sensitive to changes in the cost of medications and laboratory monitoring. Differences in efficacy and compliance between therapeutic classes are small enough to have relatively little impact on the overall cost of managing hypertension. It is suggested that new guidelines for managing hypertension should consider both clinical and economic endpoints when making recommendations for pathways of care.
Source of funding Supported by Wyeth-Ayerst Laboratories.
Bibliographic details Ramsey S D, Neil N, Sullivan S D, Perfetto E. An economic evaluation of the JNC hypertension guidelines using data from a randomized controlled trial. Journal of the American Board of Family Medicine 1999; 12(2): 105-114 Other publications of related interest Comment In: Journal of the American Board of Family Practice 1999;12(5):421-2.
Neaton J D, Grimm R H Jr, Prineas R J, Stamler J, Grandits G A, Elmer P J, et al. Treatment of mild hypertension study: final results. JAMA 1993;270:713-724.
Indexing Status Subject indexing assigned by NLM MeSH Acebutolol /economics /therapeutic use; Adrenergic beta-Antagonists /economics /therapeutic use; Adult; Amlodipine /economics /therapeutic use; Angiotensin-Converting Enzyme Inhibitors /economics /therapeutic use; Antihypertensive Agents /therapeutic use /economics; Calcium Channel Blockers /economics /therapeutic use; Chlorthalidone /economics /therapeutic use; Comparative Study; Cost-Benefit Analysis; Decision Making; Decision Support Techniques; Diuretics /economics /therapeutic use; Enalapril /economics /therapeutic use; Health Care Costs; Humans; Hypertension /drug therapy /economics; Practice Guidelines as Topic; Randomized Controlled Trials as Topic; Research Support, Non-U.S. Gov't AccessionNumber 21999006778 Date bibliographic record published 31/01/2002 Date abstract record published 31/01/2002 |
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