An economic evaluation of valsartan for post-MI patients in the UK who are not suitable for treatment with ACE inhibitors
Taylor M, Scuffham P A, Chaplin S, Papo N L
 
 
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.

CRD summary

This study examined the cost-effectiveness of valsartan for the treatment after myocardial infarction of patients with left ventricular systolic dysfunction, heart failure, or both, who were not suitable for treatment with angiotensin-converting enzyme inhibitors. The authors concluded that valsartan was a cost-effective alternative to placebo from the perspective of the UK National Health Service. The study was well conducted and was satisfactorily presented. The authors’ conclusions appear to be robust, but some important assumptions were made.

Type of economic evaluation

Cost-effectiveness analysis, cost-utility analysis

Study objective

This study examined the cost-effectiveness of valsartan for the treatment of patients after myocardial infarction (MI), with left ventricular systolic dysfunction, heart failure, or both, who were not suitable for treatment with angiotensin-converting enzyme (ACE) inhibitors.

Interventions

Valsartan at a mean dose of 247mg (±105mg) per day was compared with placebo.

Location/setting

UK/secondary care.

Methods

Analytical approach:

This economic evaluation was based on a Markov model with a 10-year time horizon. The authors stated that the perspective of the UK National Health Service (NHS) was adopted.

Effectiveness data:

The clinical data came from a selection of known, relevant studies. The evidence for valsartan came from a multi-country, double-blind, randomised controlled trial; the Valsartan in Acute Myocardial Infarction (VALIANT) trial. This compared valsartan with captopril (an ACE inhibitor) in more than 14,000 patients, who had experience one MI and were followed-up for an average of 24.7 months. The data for placebo were obtained from a meta-analysis of three trials. Some assumptions were also needed as no head-to-head comparisons between valsartan and placebo were available. The key clinical endpoints were the event rates for subsequent MIs, strokes, or cardiovascular deaths.

Monetary benefit and utility valuations:

The utility valuations were derived from published studies. One of these studies used the time trade-off approach and another was a meta-analysis of pooled data on quality of life in stroke patients.

Measure of benefit:

Quality-adjusted life-years (QALYs) and life-years (LYs) were the summary benefit measures and were discounted at an annual rate of 3.5%.

Cost data:

The economic analysis included the following costs: valsartan, treatment of cardiovascular events, visits to health care professionals (general practitioners, cardiologists, and nurses), investigations (exercise tolerance test and angiography), and revascularisations (percutaneous coronary intervention and coronary artery bypass grafting). These costs were presented as macro-categories and were mainly calculated using NHS official sources and a published study. Some assumptions were made, based on expert opinions, to supplement the published data on resource consumption. All costs were in UK pounds sterling (£) for the price year 2008. Future costs were discounted at an annual rate of 3.5%.

Analysis of uncertainty:

A deterministic one-way sensitivity analysis was undertaken to identify the most influential model inputs by varying the base-case values by ±20% for most parameters. A probabilistic sensitivity analysis was carried out using probability distributions for the model inputs to generate confidence intervals (CIs) and cost-effectiveness acceptability curves.

Results

Over placebo, valsartan led to an additional cost of £2,680 and an incremental gain of 0.502 QALYs and 0.574 LYs. Thus, the incremental cost per QALY gained was £5,338 and the incremental cost per LY gained was £4,672.

Both the deterministic and the probabilistic sensitivity analyses showed that these findings were robust and there was a high degree of confidence associated with valsartan being a cost-effective intervention. The most influential model inputs were the utility weight associated with a condition of having no complications and the rate of cardiovascular death with valsartan. However in all cases the incremental cost per QALY gained remained lower than £10,000.

Authors' conclusions

The authors concluded that, from the perspective of the UK NHS, valsartan was a cost-effective alternative to placebo.

CRD commentary

Interventions:

The rationale for the selection of the comparators was clear. Valsartan was the only angiotensin II antagonist licensed for the management after MI of this patient population. Placebo was the only alternative, given that these patients were not suitable for treatment with ACE inhibitors.

Effectiveness/benefits:

The clinical data came from multiple sources. The use of a large international trial should have ensured the validity of the clinical estimates, given the strengths of its a design. The major issue for the clinical data was the possible lack of comparability between the populations involved in the various studies. The authors assumed that the ratio for valsartan versus placebo was the same as that for ACE inhibitors (obtained from the meta-analysis) versus placebo. This assumption was conservative since valsartan was statistically more effective than captopril in the VALIANT trial. Published data were supplemented with expert opinions and extensive sensitivity analysis investigated the uncertainty around these estimates. The utility weights were obtained from well-known published studies and were varied in sensitivity analyses. The use of both LYs and QALYs gained was appropriate and will allow comparisons to be made with other studies for other diseases.

Costs:

The economic analysis followed standard UK guidelines and was consistent with the perspective. Both the categories of costs and the sources of data reflected the NHS viewpoint. Some details on the costs and quantities of resources used were provided, but in general, the costs were presented as macro-categories. Most of the data on resource consumption referred to a UK sub-sample of patients enrolled in the international clinical trial, which thus reflected country specific patterns. The authors stated that some cost categories, such as the stay in nursing homes, were not included due to the lack of reliable data, but their inclusion should have favoured valsartan because better outcomes are usually associated with reduced resource use. The price year and the use of discounting were reported.

Analysis and results:

The costs and benefits were appropriately combined using incremental methods. The issue of uncertainty was satisfactorily addressed in the sensitivity analysis, which used two different approaches. In general, the findings were clearly presented. The authors noted that the use of evidence from the published literature required some assumptions and this may have been a drawback of their analysis. For instance, a key assumption of the analysis was the long-term duration of the treatment effect, while trial data were only available for 24 months.

Concluding remarks:

The study was well conducted and was satisfactorily presented. The authors’ conclusions appear to be robust, but some important assumptions were made.

Funding

Supported by Novartis Pharmaceuticals.

Bibliographic details
Taylor M, Scuffham P A, Chaplin S, Papo N L. An economic evaluation of valsartan for post-MI patients in the UK who are not suitable for treatment with ACE inhibitors. Value in Health 2009; 12(4): 459-465
DOI
10.1111/j.1524-4733.2008.00494.x
Original Paper URL
http://www.ingentaconnect.com/content/bsc/vhe/2009/00000012/00000004/art00011
Other publications of related interest

The VALIANT Investigators. Valsartan, captopril, or both in myocardial infarction complicated by heart failure, left ventricular disease, or both. N Engl J Med 2003;349:1893-906.

Flather M, Yusuf S, Kober L, et al. Long-term ACE inhibitor therapy in patients with heart failure of left-ventricular dysfunction: a systematic overview of data from individual patients. Lancet 2000;355:1575-81.

Fox KA, Goodman SG, Klein W, et al. Management of acute coronary syndromes. Variations in practice and outcome. Eur Heart J 2002;23:1177-89.

Indexing Status
Subject indexing assigned by CRD
MeSH
Angiotensin II Type 1 Receptor Blockers; Cost-Benefit Analysis; Heart Failure; Humans; Markov Chains; Myocardial Infarction; Quality-Adjusted Life Years; Tetrazoles; Valine
AccessionNumber
22009102028
Date bibliographic record published
23/09/2009
Date abstract record published
14/10/2009
 
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