title: Evaluating a combined (frequency and percentage) risk expression to communicate information on medicine side effects to patients.
abstract: OBJECTIVE
  The study evaluated the interpretation of, and preferences for, numerical information on side-effect incidence when presented in three different formats.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors: Department of Health Sciences, University of York, York, UK. peter.knapp@york.ac.uk
authors: Peter
authors: P
authors: Knapp
authors: Peter
authors: P
authors: Gardner
authors: Brian
authors: B
authors: McMillan
authors: David K
authors: DK
authors: Raynor
authors: Elizabeth
authors: E
authors: Woolf
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000009:adverse effects; D003142:Communication; D005260:Female; D006801:Humans; D020407:Internet; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000188:drug therapy; D010353:Patient Education as Topic / Q000379:methods*; D057240:Patient Preference; D012306:Risk; D013629:Tamoxifen / Q000009:adverse effects*; D055815:Young Adult
chemical_list: D018931:Antineoplastic Agents, Hormonal; D013629:Tamoxifen
keywords: RCT; harm; information; medicines; risk; tamoxifen