BACKGROUND: Prostate cancer screening with serum prostate-specific antigen (PSA) and digital rectal examination (DRE) continues to increase. Our goal was to test the effect of a prostate cancer screening decision-aid on patients’ knowledge, beliefs, and use of prostate cancer screening tests.
METHODS: Our study was a randomized controlled trial of a prostate cancer screening decision-aid consisting of an illustrated pamphlet as opposed to a comparison intervention. We included 257 men aged 50 to 80 years who were receiving primary care at a Department of Veterans Affairs Hospital in Milwaukee, Wisconsin. The decision-aid provided quantitative outcomes of prostate cancer screening with DRE and PSA. We subsequently evaluated prostate cancer screening knowledge, beliefs, and test use.
RESULTS: The illustrated pamphlet decision-aid was effective in improving knowledge of prostate cancer screening tests: 95% of the experimental group were aware of the possibility of false-negative test results compared with 85% of the comparison group (P <.01). Ninety-one percent of the experimental group were aware of the possibility of a false-positive screening test result compared with 65% of the comparison group (P <.01). However, there was no difference in the use of prostate cancer screening between the experimental (82%) and comparison (84%) groups, (P >.05).
CONCLUSIONS: When used in a primary care setting, an illustrated pamphlet decision-aid was effective in increasing knowledge of prostate cancer screening tests but did not change the use of these tests.
The practice of prostate cancer screening with serum prostate-specific antigen (PSA) and digital rectal examination (DRE) continues to increase, despite ongoing debate in the medical community on the efficacy of screening in reducing prostate cancer mortality.1-5 Prostate cancer screening remains controversial because of concern that mass screening may lead to the detection and treatment of clinically insignificant lesions, exposing an asymptomatic population to significant morbidity.4
It is widely recommended that patients be well informed of potential risks and benefits before engaging in a prostate cancer screening program.2,6-10 The health risks of prostate cancer screening include those of the initial tests, indicated follow-up tests (transrectal ultrasound [TRUS] or rectal biopsy), and therapeutic interventions. For example, an asymptomatic patient who is given a diagnosis of early-stage prostate cancer as a result of screening and is treated with a radical prostatectomy may develop impotence as a complication of treatment. Such a patient would have significant morbidity despite the fact that his cancer may have remained clinically silent throughout his lifetime. Also, the survival benefits of early detection and treatment of prostate cancer are unproven. Thus, the decision regarding prostate cancer screening provides clinicians and patients with a dilemma that involves informed decision making and patient input.
Previous studies report mixed results of the effect of decision-aids on the use of prostate cancer screening tests.11-13 One study reported a decrease in the use of such tests after exposure to a decision-aid in a primary care setting but no effect in a free PSA clinic.11 A second study found decreased interest in PSA screening after exposure to a decision-aid but did not evaluate screening test use.12 Finally, a third study found no effect of a decision-aid intervention on the use of prostate cancer screening tests.13 There is a need for further data on the effect of theoretically based decision-aids on men’s decisions to undergo prostate cancer screening.
Methods
We conducted a randomized controlled trial to test the effect of a prostate cancer screening decision-aid-an illustrated pamphlet-on patients’ knowledge, beliefs, and subsequent use of PSA and DRE prostate cancer screening tests.
Study Protocol
We included men aged 50 to 80 years who had an outpatient encounter in the years 1990 to 1995 at the Clement J. Zablocki Veterans Affairs Medical Center (VAMC) in Milwaukee, Wisconsin. We excluded men who had a history of prostate or other cancer, a previous prostate ultrasound study or biopsy, cystoscopy, prior prostate surgery, active genitourinary symptoms, cognitive impairment (defined by a Mini-Mental State Examination score of 23 or less), an anticipated life expectancy of less than 2 years, or who were currently employed by the VAMC. Potential subjects were identified from a randomly generated computerized list of patients who had received care at the VAMC in the designated time period. Patients were mailed a letter describing the study and inviting those interested to call and be considered for enrollment. The study protocol was approved by the Institutional Review Board of the VAMC and the Medical College of Wisconsin, and we obtained informed consent from all study participants.
The study protocol required 2 visits to the VAMC. At the initial study visit, subjects were randomized and baseline knowledge and belief surveys were administered. Data were also obtained on comorbidity using the Charlson comorbidity index and on reading level using the Rapid Estimate of Adult Literacy (REALM) instrument.14,15 Subjects were then given the experimental or the comparison intervention, each consisting of a written pamphlet to read and review. A research assistant was present when the subject reviewed the pamphlet and was available to answer questions. Postintervention knowledge and belief surveys were administered at the end of the initial study visit. A follow-up visit was scheduled with the subject’s primary care physician or one of the research investigators (JV or MMS) approximately 2 weeks after the initial study visit. At the follow-up visit, the subject was asked if he wanted to undergo prostate cancer screening with a PSA and a DRE. If the subject asked for the physician’s opinion, a scripted response was provided. The response emphasized the tossup nature of the decision and encouraged the patient to make up his own mind about prostate cancer screening. Men with a PSA test result that was greater than or equal to 4.0 ng/dL or those whose DRE was abnormal (asymmetric, indurated, or with a nodule) were referred to a urology clinic for confirmatory testing by TRUS and prostate biopsy. The screening tests were offered to at no cost. At the time of the study, there was no formal recommendation at the clinical site on the use of PSA for prostate cancer screening.