Adherence to Discounting Guidelines: Evidence from Over 2000 Published Cost-Effectiveness Analyses

Previous studies have shown that not all cost-effectiveness analyses (CEAs) adhere to recommended guidelines on intertemporal discounting. This analysis investigates adherence in a sample of over 2000 CEAs from seven countries. Guideline discount rates were retrieved for Australia, Belgium, Canada, Ireland, The Netherlands, New Zealand and the UK. Data on the rates applied in published CEAs were retrieved from the Tufts CEA Registry from the sample countries within the periods covered by the discounting guidelines. The relationship between adherence and candidate explanatory factors were assessed using logistic regression. The analysis appraised 2270 CEAs. The overall rate of adherence to discounting recommendations was 79%. Country-specific adherence ranged from 28% in New Zealand to 87% in Belgium and the UK. Adherence in Australia and Canada was 73% and 66%, respectively. Adherence is statistically significantly higher in more recent studies, countries currently applying differential discounting and manufacturer-sponsored studies. Relative to the reference case of Australia, adherence is statistically significantly higher in the UK and lower in Canada and New Zealand. There is notable variation in the rates of adherence to discounting recommendations between countries and over time. Incomplete adherence raises concerns regarding the comparability of evidence between studies. In turn, this raises concerns regarding equity of access to scarce healthcare resources. Journal editors should ensure that adherence to discounting recommendations is assessed as part of the peer review process.