Evaluating a combined (frequency and percentage) risk expression to communicate information on medicine side effects to patients
Article first published online: 9 NOV 2012
© 2012 The Authors. IJPP © 2012 Royal Pharmaceutical Society
International Journal of Pharmacy Practice
Volume 21, Issue 4, pages 226–232, August 2013
How to Cite
Knapp, P., Gardner, P., McMillan, B., Raynor, D. K. and Woolf, E. (2013), Evaluating a combined (frequency and percentage) risk expression to communicate information on medicine side effects to patients. International Journal of Pharmacy Practice, 21: 226–232. doi: 10.1111/j.2042-7174.2012.00254.x
- Issue published online: 10 JUL 2013
- Article first published online: 9 NOV 2012
- Manuscript Accepted: 3 AUG 2012
- Manuscript Received: 14 DEC 2011
The study evaluated the interpretation of, and preferences for, numerical information on side-effect incidence when presented in three different formats.
It used a controlled design, with participants allocated at random to receive one of the three formats. Participants were recruited via a pop-up window on the CancerHelp UK website. The sample comprised 129 website users, of whom 96% were women and 86% had cancer, who received frequency information on four side effects of tamoxifen, using one of three risk expressions (percentages, e.g. ‘affects 25% of people’; frequencies, e.g. ‘affects 1 in 4 people’; combined, e.g. ‘affects 1 in 4 people (25%)’). They then interpreted information on tamoxifen and its effect on health, and estimates of side-effect frequency, and then stated a preference from the three risk expression formats.
The results showed that the three formats did not influence participants’ ratings of the information or their side-effect estimates. However, more than half (53%) the participants preferred the combined (frequency and percentage) format. In conclusion, a combined risk expression format performed no worse than percentages or frequencies alone and was preferred by a majority.
The three risk expression formats did not differ in their effect on participants’ interpretations. However, the preferred format was the combined (frequency and percentage) risk expression.