Cost-effectiveness studies are widely used to guide prescribing
policy in many countries, as part of health technology assessment
programmes. However, a new study published this week in /PLoS//
Medicine/ by Tjeerd-Pieter van Staa and colleagues suggests that
cost-effectiveness analyses based on data from randomized controlled
trials may not be realistic enough to accurately inform policy.
In the study the researchers (affiliated with the General Practice
Research Database, and London School of Hygiene & Tropical Medicine
in the UK, and Utrecht University in the Netherlands) specifically
examine the relative cost-effectiveness of two commonly used groups
of painkillers: selective cyclooxygenase-2 inhibitors (cox-2
inhibitors), versus conventional nonsteroidal anti-inflammatory drugs
(NSAIDs). One type of cox-2 inhibitor has now been withdrawn from use,
and recommendations regarding the use of others have changed as a
result of data on cardiovascular harms associated with these drugs.
The researchers collected data on the risk of upper gastrointestinal
effects associated with use of either type of drug, and calculated
the cost-effectiveness of the drugs in relation to these events using
either data from large randomized controlled trials or from routine
clinical practice using the UK General Practice Research Database.
These analyses showed that the average cost of preventing an upper
gastrointestinal effect by switching NSAIDs for a cox-2 inhibitor was
calculated at roughly US$104K, using the data from routine clinical
practice. However, the cost effectiveness was calculated as around
US$20K using randomized trial data.
The researchers suggest that in the specific scenario evaluated here,
patients in the randomized trials experienced more gastrointestinal
events than patients in routine practice, and that they used drugs
differently commonly involving higher daily doses leading to a
different estimate of cost-effectiveness. A more realistic assessment
might have led to differences in prescribing guidelines, according to
the authors. Tjeerd-Pieter van Staa says:
Real-world questions on what to prescribe to whom should consider
the varied group of patients in actual clinical practice rather than
just using data from highly selective randomized trials that have
narrow inclusion criteria.
However, one limitation of the study is that it involves an
assessment of cost-effectiveness of two specific types of
painkillers, and it isn t clear whether the observations will apply
to cost-effectiveness for other drug classes.
Funding: The authors received no specific funding for the paper. LS
is funded by a Wellcome Trust Senior Research Fellowship in Clinical
Science.
Competing Interests: TPvS and BZ: The General Practice Research
Database receives funding from the Medicines and Healthcare products
Regulatory Agency, pharmaceutical companies, universities, and
contract research organizations. TPvS and HGML: The Utrecht Institute
for Pharmaceutical Sciences at Utrecht University has received
unrestricted funding for pharmacoepidemiological research from
GlaxoSmithKline, Novo Nordisk, the private-public funded Top
Institute Pharma (tipharma.nl; includes co-funding from
universities, government, and industry), the Dutch Medicines
Evaluation Board, and the Dutch Ministry of Health. LS is funded by a
Wellcome Trust Senior Research Fellowship in Clinical Science.
Citation: van Staa T-P, Leufkens HG, Zhang B, Smeeth L (2009)
"A Comparison of Cost Effectiveness Using Data from Randomized Trials or
Actual Clinical Practice:
Selective Cox-2 Inhibitors as an Example. "
PLoS Med 6(12): e1000194.
doi:10.1371/journal.pmed.1000194