Denial of effective treatment and poor quality of clinical information in placebo controlled trials of ondansetron for postoperative nausea and vomiting: a review of published trials.

OBJECTIVE

To determine how many patients were deprived of treatment by being given placebo as comparator in trials of ondansetron for postoperative nausea and vomiting.

DESIGN

Review of published trials of ondansetron during 1991 to July 1994.

SETTING

Medline search in a university department of anaesthesia.

SUBJECTS

8806 patients who had been included in 18 indexed placebo controlled trials of ondansetron as prophylaxis against or treatment of postoperative nausea and vomiting.

RESULTS

Five studies (1236 patients) had been published by July 1992. All were placebo controlled trials. By July 1994, 8806 patients had been included in 18 indexed placebo controlled studies of prophylaxis or treatment. Only 462 patients had been in studies that compared ondansetron with other drugs, and there were no indexed comparative trials of treatment of nausea and vomiting. Roughly 2180 patients had been given placebo as prophylaxis and 440 had been given placebo when already experiencing postoperative nausea or vomiting.

CONCLUSIONS

Around 2620 patients in the reviewed studies were denied existing drugs, which, though not completely effective or without side effects, do bring some relief from postoperative nausea and vomiting. Drug regulatory bodies should collaborate with drug companies to ensure better comparison of new with established drugs. This would avoid placebos being given to more than the fewest patients necessary to confirm effect and would allow doctors to be informed more quickly about relative efficacies.