Clinical trial participants may not be as unrepresentative of general clinical populations as often reported

Sep 26 2005

It is often suggested that the results of clinical trials are affected by the fact that the patients who volunteer for a trial are more likely to take their medication effectively than those in standard care. This supposition is, however, strongly refuted in the results of a new study revealed at the British Pharmaceutical Conference in Manchester.

The study, carried out by the University of Brighton and the University of Sussex, investigated the hypothesis: is it appropriate to transfer trial findings to routine practice, given that clinical trial volunteers may be atypical of patients in standard care?

This new study compared 230 hypertensive patients who were taking part in an Anglo-Scandinavian cardiac clinical trial, with those of a previously reported non-trial sample. Using a questionnaire, the participants reported their adherence to medication, as well as their perceptions of illness and treatment.

Contrary to expectation, there was no significant difference in self-reported adherence to medication between the trial and the non-trial samples. Whilst those in the trial reported a stronger belief in the efficacy of medication and lower concerns about taking medication, these differences were small.

In both the trial and the non-trial sample there was an association between patients' reported adherence to medication and their beliefs about hypertension and its treatment. Low reported adherence was associated with concerns about taking antihypertensives. In both samples, those in the high adherence group reported lower emotional consequences of hypertension when compared to the low adherence group.

Pharmacist Rob Horne who led this study says: "The results clearly indicate that clinical trial participants may not be as unrepresentative of general clinical populations as often reported."