A distinctive feature of our study is the use of a written pamphlet (as opposed to a videotape or a verbal discussion) as the decision-aid modality. Written materials are a commonly used method of educational support26 and in some studies have been preferred by patients to audiotapes or interactive computer materials.27 Patients respond favorably to having written materials that can be taken home to discuss with family or friends.28 However, written materials lack the ability of videotapes or discs to present video and audio role models for the deliberative decision-making process.23,29-30 Future studies are needed to examine the efficacy of written versus audiovisual modalities in presenting clinical outcomes to patients.
Our study supports the use of visual displays of frequencies when presenting information to patients. Human figure representations were used to visually convey the incidence of prostate cancer and the frequency of false-positive and false-negative test results (Figure 1). This approach was successful in improving knowledge regarding test characteristics. The visual display of quantitative information is an area of inquiry with important applications for communication of outcomes to patients.31-35 Previous studies have found that presenting very small probabilities with the use of dot diagrams has influenced the patient’s willingness to take risks.36 More work is needed on how best to display quantitative information in medical settings.
Limitations
Our study had some limitations. First, results were subject to volunteer bias, since the recruitment strategy required that interested patients reply to a mailed study invitation letter. The low rate of participation is similar to that found in previous prostate cancer screening studies that recruited subjects using mailed letters.37 Second, the study protocol removed some of the barriers to prostate cancer screening in the usual care setting. Subjects were offered prostate cancer screening on-site at the time of the follow-up study visit and did not have to pay for screening or follow-up tests. These 2 limitations may bias the study toward higher baseline levels of screening but should not differentially affect the comparison or intervention group. Finally, the current study evaluates knowledge, beliefs, and the subsequent use of prostate cancer screening tests. Other relevant outcomes, including decisional conflict, satisfaction with the decision-making process, and persistence of decision choice, deserve study in future research.
Conclusions
It is increasingly recognized that an informed decision-making process is appropriate before the use of cancer screening tests, especially those that lack strong efficacy evidence from clinical studies.2,6-10 Screening interventions are done in a healthy population during routine office visits, when limited time is available for the physician-patient encounter, and must be feasible in a busy office setting. Ideally, a decision-aid would be self-administered with the option of a follow-up interaction with the physician or another health care provider. Several modes of providing information can be used in this way, including a pamphlet, videotape, or interactive video-disk format. The pamphlet in our study was produced at a low cost, used graphic designs to help convey quantitative information, and was available for patients to take home and review. Simple decision-aids remain a viable method of presenting of complex information for preventive interventions such as prostate cancer screening. Further study is needed to understand the most effective decision-aids.
Acknowledgments
Our research was supported by the Department of Veterans Affairs, Veterans Health Administration, Health Services Research and Development Service (project no. SDR 93-005). Dr Schapira is Director of General Internal Medicine Research at the Medical College of Wisconsin and the Clement Zablocki Veterans Affairs Medical Center in Milwaukee, Wisconsin.