Physicians expect a treatment to be more effective when its clinical outcomes are described as relative rather than
as absolute risk reductions. We examined whether effects of presentation method (relative vs. absolute risk reduction)
remain when physicians are provided the baseline risk information, a vital piece of statistical information omitted in
previous studies. Using a between-subjects design, ninety five physicians were presented the risk reduction associated
with a fictitious treatment for hypertension either as an absolute risk reduction or as a relative risk reduction, with or
without including baseline risk information. Physicians reported that the treatment would be more effective and that
they would be more willing to prescribe it when its risk reduction was presented to them in relative rather than in
absolute terms. The relative risk reduction was perceived as more effective than absolute risk reduction even when the
baseline risk information was explicitly reported. We recommend that information about absolute risk reduction be
made available to physicians in the reporting of clinical outcomes. Moreover, health professionals should be cognizant
of the potential biasing effects of risk information presented in relative risk terms.
