Thu18November0303AM 1

A pharmaceutical representative shows you a summary of a publication recommending use of their company's antiemetic to prevent postoperative nausea and vomiting. The publication appeared in a peer reviewed journal. You read the article and consider whether to change your current practice, which is to use cyclizine intraoperatively.

Which type of publication is most likely to provide the best evidence on which to base changes to your practice?

(Please select 1 option)

A case controlled series of patients matched for types of anaesthesia and operation

A prospective randomised double blind controlled trial against cyclizine in multiple centres Correct

A case controlled series of patients matched for types of anaesthesia and antiemetic prophylaxis

A prospective randomised double blind controlled trial against ondansetron in a single centre

A prospective randomised double blind controlled trial against placebo in multiple centres

Explanation

Case controlled studies are usually conducted retrospectively and are generally less valued than prospective randomised trials. They are very efficient in identifying an association between a drug treatment and outcome but these studies are subject to bias, cannot generate incidence data, the selection of controls can be difficult and can be made more difficult if note keeping is unreliable.

Randomised controlled double blind trials are the "gold standard" in intervention-based studies.

The features of randomised double blind controlled studies are:

The random allocation to intervention groups aims to reduce bias

Both the patients and researchers should be unaware of which treatment was given until the study is completed

All intervention groups are treated identically

Patients are normally analysed within the group to which they were allocated, and

The analysis is focused on estimating the size of the difference in predefined outcomes between intervention groups.

Despite some potential ethical disadvantages, all new healthcare interventions should be evaluated through properly designed randomised controlled trials.

Conducting trials in multiple centres compared with a single centre is an accepted way of evaluating a new drug. It may be the only practical way of recruiting sufficient number of patients to satisfy the trial objectives within a reasonable time frame. Small numbers of patients in a study group may result in type II statistical errors. Studies evaluating anti-emetics in particular require large study groups.

A prospective randomised double blind controlled trial against the drug you normally use (cyclizine) in multiple centres is most likely to change your practice.

Answer Statistics

1

2%

2

72%

3

2%

4

2%

5

23%

Times answered: 248