Systematic reviews and economic evaluations conducted for the National Institute for Health and Clinical Excellence in the United Kingdom: A game of two halves?

C.P.I. and N.J.C. are funded by an MRC Training Fellowship in Health Services Research. An earlier version of this paper was presented at the International Health Economics Association 6th World Congress, Copenhagen, July 8-11, 2007. We are also grateful for comments from an anonymous referee.

Economic evaluations require clinical data for the assessment of the cost-effectiveness of healthcare treatments and programs. The gold standard approach is to conduct a systematic review of the relevant clinical literature, in particular for the estimation of relative treatment effects, a key parameter in economic decision analytic models.

A recent study of technology assessments undertaken in the United Kingdom showed that systematic reviews are often used and that this is the most prevalent approach (78 percent) for the estimation of relative treatment effect (4). However, several other approaches were also used to populate economic models. Studies of the general economic evaluation literature demonstrate an even lower use of systematic reviews. For example, Hanratty et al. (7) found that only a small proportion of published economic studies used systematic reviews that would have been available at the time the study was conducted. There is therefore a risk that the estimates of cost-effectiveness could be biased.

The objective of this research was to investigate the reasons why systematic reviews are not used, by examining situations where one might expect such reviews to be undertaken. There are several reasons why those conducting economic evaluations do not use data from systematic reviews. First, such reviews may not be available. Second, some economists may be unaware of the need to use unbiased estimates of clinical effect, although this seems unlikely. Much more likely is the possibility that the economist does not have the time or resources to conduct a systematic review in situations where no reviews exist. Finally, there is the possibility that, although systematic reviews exist, they are not able to be used in the economic evaluation.

The technology assessment reports (TARs) undertaken for NICE are an excellent vehicle for studying the link between systematic reviews and economic evaluations for two main reasons. First, the contract for TARs requires that the evaluation team conducts a systematic review to provide parameter estimates for an economic evaluation (usually based on an economic model). Second, there is...