They believe it would lessen the risk of wishful thinking an unconscious tendency by doctors to expect new drugs to perform better than the older ones they are being tested against.
This perception of a drugs effectiveness was named wish bias', when it was first reported more than a decade ago. In a report published in the current issue of Annals of Oncology* the research team says it may help to explain why the response rate of tumours to a new drug decreased over time.
Dr Roldano Fossati and colleagues from the Mario Negri Institute in Milan combed through the results of 29 randomised trials that took place between 1975 and 1999. They analysed the response rate of 2,234 women with advanced breast cancer who had been in the arms of the trials using the anti-cancer drug, doxorubicin (Adriamycin). They extracted the global (i.e. complete plus partial) response rate from all the trials.
"We found that every five years there was a 11% relative decrease in the odds of a global response and most of this decrease was in the partial response rate, where evaluation involves more subjective judgement than is involved in determining complete response," said Dr Fossati.
Of the 29 studies they investigated, only one had used a double blind** approach, and in two studies patients records were just externally audited.
"In these situations a bias due to financial and academic conflicts of interest or more subtle forms of wish bias could easily arise and account for an impression that when a drug is new it does better," said Dr Fossati.
The team carried out the assessment of the 29 studies to test their hypothesis that doctors unconscious favourable attitudes to new treatments may result in a tendency to overestimate their
Contact: Margaret Willson
European Society for Medical Oncology