Effect of the Prosdex decision support tool on attitudes to PSA testing


In the UK, a nationally developed, on-line decision support tool known as Prosdex is available and is used by at least some men to help them make decisions about whether they wish to undergo PSA testing. The Prosdex system is based on information developed in conjunction with an expert, multi-disciplinary, advisory group to the national Prostate Cancer Risk Management Programme. The Prosdex system is not itself widely promoted, but the information included in the system has been widely disseminated to primary care physicians for distribution to patients.

In the UK, PSA testing is available to any patient who wishes to receive it, but there is no national prostate cancer screening initiative. The Prosdex system offers a methodology whereby patients can work with their primary care physicians to appreciate the pros and cons of PSA testing (in a manner that is now being recommended by most of the US guidelines for the use of PSA testing) and come to an informed, shared decision with their primary care providers about the value of PSA testing on an individual basis.

The Prosdex system is probably not appropriate in detail for use by US patients and their physicians. Just for example, the percentage of men of historic African ethnicity in the US is significantly higher than in the UK, and so a US-based system might wish to place greater emphasis, earlier in the contents, on ethnicity for risk for prostate cancer. The Prosdex system also does not address the appropriateness of PSA testing for men of less than 50 years of age.

A newly published paper by Evans et al. has reported on the impact of the use of the Prosdex system on men’s attitudes to PSA testing. The full text of this paper is available on line. All study participants were between 50 and 75 years of age and had never received a PSA test. The study randomized participants to one of four possible groups:

  • Group A — men who used the online Prosdex system to learn about PSA testing and then completed an on-line questionnaire.
  • Group B — men who used a paper-based version of the online Prosdex system and then completed the on-line questionnaire.
  • Group C — men who did not receive Prosdex-type education but did complete the on-line questionnaire.
  • Group D — men who did not receive Prosdex-type education and did not complete the questionnaire.

The study was designed to assess the effect of exposure to the Prosdex system on a variety of different outcomes, including knowledge about prostate cancer and PSA testing, attitudes toward PSA testing, intention to undergo PSA testing, decisional conflict and anxiety, and actual use of PSA testing within 6 months of study participation.

The core results of the study are reported as follows:

  • A total of 514 participants were enrolled in the study.
  • After completion of the on-line questionnaire, compared to men in Group C, men in Groups A and B
    • Had greater knowledge ( i.e., a knowledge increase of at least 20 percent) about the PSA test and prostate cancer
    • Had less favorable attitudes to PSA testing
    • Were  less likely to undergo PSA testing
    • Had less decisional conflict
    • Had a similar anxiety level.
  • For the five outcomes above there were no significant differences between men in Groups A and B.
  • For the men in Group A, increased knowledge was associated with a less favorable attitude toward testing  and lower intention to undergo testing compared to men in Group B.
  • Within 6 months, actual PSA test uptake was lower in Group A (3.1 percent) than in Group B (9.1 percent) or Group C (8.9 percent).
  • PSA test uptake was also lower in Group D than in Group C, suggesting that just taking the on-line questionnaire affected the likelihood of PSA testing (a so-called Hawthorne effect).

Evans and his colleagues conclude that exposure to Prosdex was associated with improved knowledge about the PSA test and prostate cancer and that men who had a high level of knowledge had a less favourable attitude toward and were less likely to undergo PSA testing. They also claim that “Prosdex appears to promote informed decision making regarding the PSA test.”

A safer set of conclusions might be that exposure to Prosdex changed men’s attitudes toward PSA testing and their resulting behavior and led to a less favorable attitude toward PSA testing and a reduced likelihood that men would actually undergo PSA testing. Whether this is actually constitutes “better” informed decision-making probably depends on whether one agrees with the way in which Prosdex presents information and the actual information provided. It is relevant that the Prosdex system was developed and this study was initiated before the results of the ERSPC trial or the Göteborg screening trial were published, so it is hard to tell whether the results of these studies would have impacted any of the results of the current study.

It is striking that less than 10 percent of the participants in Groups A, B, or C actually appear to have undergone PSA testing within 6 months of their participation. (For Group D — the men who received no education and did not take the online survey — only 1.6 percent had a PSA test within 6 months after their “participation” in this study).

While one may disagree with the conclusions of this study because one disagrees with the content or the emphasis on certain types of information in the Prosdex system, what this study most certainly does show is that a relatively simple, neutral, and widely used on-line system could be developed and could be used by individual men and by the primary care community in any nation to encourage men to become better informed about the risks and benefits of PSA testing.

2 Responses

  1. This would be useful if the prostate cancer mortality rate in the UK were lower than in places were more men are tested with PSA. The bottom line is that the program saves money. …

  2. I have read the site and I must say it is not very helpful. The information provided is very high level and lacks in specificity. For example, it mentions the different risks, but without any numbers attached. So a person reading it cannot find any information on what the probability is of suffering from certain side effects. The site mentions the fact that prostate cancer is more common as the patient progresses in age and, if appearing at a younger age (less than 60; less than 50?), it is commonly more aggressive. However, it has no suggestion on how to look at PSA results depending on a man’s age.

    It makes the same mistake as many other sites and counts “active surveillance” as treatment. I would like to emphasize for the thousandth time that “active surveillance” is NOT treatment. It is a decision to postpone treatment until stronger evidence of prostate cancer aggressiveness and stage, such as higher PSA, higher PSA velocity, Gleason score, etc.

    The Prosdex site mentions the fact that chance of survival is higher if cancer has not spread, but does not tie that to early detection and through that to PSA screening.

    I checked the bibliography and was surprised that no article was more recent than 2003. Most of the articles are 10 years old. I think we have gained some insights into prostate cancer, the merits of early detection, PSA testing, etc., since then.

    The NHS (UK) Prostate Cancer Risk Management Programme has an information sheet that should be handed out to patients in preparation for a discussion on PSA testing. The information sheet is presented in a way that will certainly influence the patient to reject a suggestion to have a PSA test. It emphasizes the dangers and the mis-diagnosis and over-diagnosis without any reference to the patient’s age. Thus an 80-year-old and a 55-year-old are getting the impression that their probability of dying of causes other than prostate cancer are equal. The only numerical information is that it takes 48 patients to be treated in order to save one life.

    I think Prosdex would make Dr. Brawley proud.

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