Health technology assessment

Chapter 5 Health technology assessment



Michael Rawlins



Synopsis


Health technology assessments bridge the gap between licensing and everyday clinical practice.


They involve:



• Defining the scope of the assessment.


• Assessing the overall clinical effectiveness.


• Assessing the cost-effectiveness.


The critical steps involve:



• A systematic review of the evidence.


• Estimating cost-effectiveness.


• Drawing appropriate conclusions on which decision-makers can act.


A cost–effectiveness analysis attempts to provide a rational basis for decision-making in the face of resource constraints.


Pharmacoeconomics involves trying to estimate the extra cost to the health-care system of adopting a product, in relation to the additional benefit the product might bring.


Health technology assessment, in its broadest application, involves a systematic assessment of the clinical and cost-effectiveness of either a single, or several similar, health technologies.


The term health technology encompasses all approaches to the prevention, screening, diagnosis and treatment of disease. Treatments, in health technology assessments, not only encompass pharmaceuticals (including vaccines) but can include devices and interventional (surgical) procedures as well as techniques such as physiotherapy, speech therapy or cognitive behavioural therapy. Although this chapter is concerned with health technology assessment as it relates to pharmaceuticals, the same approach is adopted in these other therapeutic areas.


For pharmaceuticals, health technology assessment of single products, or of a group of similar products, bridges the gap between licensing and use in everyday clinical practice. The process involves the close scrutiny of a product’s clinical effectiveness in comparison with other forms of treatment (including best supportive care), together with its cost-effectiveness in comparison with these same alternatives. It therefore goes further than the criteria for licensing (quality, safety and efficacy), and health technology assessment has sometimes been called ‘the fourth hurdle’.


A health technology assessment may be used by a variety of agencies. It may inform the decisions of individual practitioners in the treatment of their own patients or it may be used by a hospital to develop their treatment policies. Health technology assessments are critical for those developing clinical guidelines for the management of specific conditions; and they may be used by policy makers for an entire health-care system.


There are three stages in the health technology assessment of a product:



• Definition of the scope of the assessment.


• Assessment of its clinical effectiveness.


• Assessment of its cost-effectiveness.



The scope


Before embarking on the health technology assessment of a product the scope of the enquiry needs to be carefully defined:



1. Obviously the product, or group of products, under investigation needs to be characterised.


2. The nature of the comparator health technology (or technologies) also requires definition. Depending on the circumstances, the comparator might be another pharmaceutical product indicated for the same condition; it might be a device or procedure used for the same or similar purposes; or it might be ‘best supportive care’. In any event, the comparator should reflect current clinical practice.


Difficulties arise when a potential comparator is not licensed for a particular indication but is, nevertheless, used in clinical practice. This is a particular problem in the heath technology assessment of products for use in children and for whom potential comparators reflect ‘custom and practice’ even though unlicensed. The wise course of action, in such circumstances, is to include comparators that reflect current clinical practice.


3. At the start of any health technology assessment, the clinical outcome(s) of interest should be decided. The most desirable, of course, is the ‘ultimate outcome’, such as dead versus alive or recovered versus not recovered. There are circumstances, however, when an assessment is focused on an ‘intermediate’ (or surrogate) outcome where there is confidence that this reflects the ultimate outcome. For example, in the assessment of statins for the treatment of hypercholesterolaemia, a decision would need to be taken as to whether the long-term ‘ultimate’ outcome (i.e. reduction in coronary artery disease) should be used; or whether the assessment should be concerned with an ‘intermediate’ outcome (i.e. a reduction in LDL cholesterol).


4. The type of evidence required to demonstrate the effectiveness of a product must also be determined. In many instances this may be restricted to the results of randomised controlled trials. There may be circumstances where other study designs are more appropriate. In the assessment of a vaccine, for example, evidence from randomised controlled trials may usefully be supplemented by the results of observational studies that have examined its efficacy under circumstances that more closely reflect its performance in the ‘real world’.


5. Decisions must also be made about the form any economic evaluation should take. These include the economic perspective and the type of analysis that is most appropriate. These issues are discussed later.



Clinical effectiveness


An assessment of the clinical effectiveness of a product requires a full ‘systematic review’ of the available evidence. A systematic review involves four steps:



1 Developing the protocol


The development of a protocol for a systematic review is just as important in secondary research as it is for primary research. The objectives of the review will usually have been defined by the scope (as above). The protocol will, in addition, include the relevant:



• pharmacological product or therapeutic class


• comparator(s) which may include a non-pharmacological procedure


• study designs for assessing the effectiveness of the product


• clinical endpoints used in the studies that are to be included in the review.



2 Defining the methods


The literature search will, at a minimum, involve a comprehensive search of the three major electronic databases (MEDLINE, EMBASE and CENTRAL). Although there is some overlap between each database, one alone is inadequate. The usual approach is to start the search in a broad manner by looking at the abstracts of all the studies that appear to be relevant and then only include those that match the criteria that have been established for the review. In a review of the clinical effectiveness of statins, for example, the review criteria may have required the assessment to be restricted to randomised controlled trials where the outcome is the secondary prevention of vascular death or disability. All other study designs, involving different patient populations or surrogate outcomes, would be excluded. The search will also include any relevant references gleaned from scrutiny of the list of publications in the included studies.


One of the major problems in identifying appropriate studies in any systematic review is so-called ‘publication bias’. There is a tendency for negative studies, or those demonstrating only very modest benefits, to either remain unpublished or to be published in a non-English language journal. The inclusion of such studies is extremely important if a reliable indication of the product’s ‘effect size’ is to be made. Common techniques to avoid publication bias include enquiry of both the particular manufacturer as well as of known experts in the particular field. The assessment team must also decide whether to attempt to identify articles in non-English language journals and get them translated. This step substantially increases the cost of the review and is not invariably undertaken.



3 Analysing the data


After extracting the relevant data from each of the studies that meet the review inclusion criteria an ‘evidence table’ is constructed. In such a table the relevant data for each study are summarised and usually include:



• The study’s bibliographic reference.


• The type of study (e.g. randomised controlled trial, case–control study).


• Number of patients in each arm.


• Patient characteristics (e.g. age, gender).


• Study setting (e.g. hospital inpatients, GPs’ surgeries).


• Intervention(s) including dose(s) and route(s) of administration.


• Comparator interventions (e.g. placebo, active comparator).


• Length of follow-up.


• Outcome measure(s) and effect size(s).


• Additional comments.

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Jun 18, 2016 | Posted by in PHARMACY | Comments Off on Health technology assessment

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