Patients prefer pictures to numbers to express cardiovascular benefit from treatment

This study aimed to determine which methods of expressing a preventive medication's benefit encourage patients with known cardiovascular disease to decide to take the medication and which methods patients prefer.

We identified patients in Auckland, New Zealand, family practices located in areas of differing socioeconomic status who had preexisting heart disease (myocardial infarction, angina, or both) and were taking statins. The patients were interviewed about their preference for methods of expressing the benefit of a hypothetical medication. Benefits were expressed numerically (relative risk, absolute risk, number needed to treat, odds ratio, natural frequency) and graphically. Statistical testing was adjusted for practice.

We interviewed 100 eligible patients, representing a 53% response rate. No matter how the risk was expressed, the majority of patients indicated they would be encouraged to take the medication. Two-thirds (68) of the patients preferred 1 method of expressing benefit over others. Of this group, 57% preferred the information presented graphically. This value was significantly greater (P <.001) than the 19% who chose the next most preferred option, relative risk. Few patients preferred absolute risk (13%) or natural frequencies (9%). Only a single patient (1%) preferred the odds ratio. None preferred number needed to treat. Ninety percent of patients responding to a question about framing preferred positive framing (description of the benefit of treatment) over negative framing (description of the harm of not being treated).

Although number needed to treat is a useful tool for communicating risk and benefit to clinicians, this format was the least likely to encourage patients to take medication. As graphical representation of benefit was the method patients preferred most, consideration should be given to developing visual aids to support shared clinical decision making.