Human ability and the Minnesota State Fair

Apparently we are not very good at being able to estimate risk associated with a diagnosis of prostate cancer … and specifically risk of death within 15 years. Labine et al. (abstract no. MP04-08) presented relevant data at the annual meeting of the American Urological Association in San Diego on Friday. The presentation is also discussed in a report on the MedPage Today web site.

The authors recruited a series of adults, all over 18 years of age, at the Minnesota State Fair. The participants were given a post-surgical pathology report for a 69-year-old male prostate cancer patient who had a Gleason score of 4 + 5 = 9 and a pathological stage of T3aN1M0. The participants were then asked to do two things:

  1. To estimate the chance that the patient would be alive in 15 years by using unrestricted internet searching
  2. To re-estimate the same chance using a freely available, validated, prostate cancer nomogram (but we can’t tell which one)

The participants’ answers were then compared to the accurate estimate (88 percent) provided by the nomogram and to a “ballpark” correct estimate (88 ± 10 percent, i.e., anywhere between 78 and 98 percent). What these data tell us is that the nomogram used might be the post-surgical nomogram on the Memorial Sloan-Kettering Cancer Center web site; the latest update to that nomogram projects an 89 percent 15-year survival for a patient of this type.

Here is what Labine and his colleagues reported:

  • 140 participants took the survey.
  • 129/140 participants (92 percent) correctly completed both questions and met inclusion criteria.
    • 85 participants were female.
    • 105 participants were Caucasian.
    • 99 participants had earned a bachelor’s degree of higher.
    • The average age of participants was 47 ± 15.5 years.
  • When using unrestricted internet searching, just 19 percent of participants gave an answer that was within the “ballpark”correct range.
  • When using the nomogram,
    • 23 percent of participants got the correct answer of 88 percent.
    • > 50 percent of participants got an answer that was within the “ballpark” correct range (i.e., 78 to 98 percent).

Labine and his colleagues conclude that:

Most adults significantly underestimated 15 year cancer specific survival for a prostate cancer patient using unrestricted internet searching. When using a validated online nomogram, most participants were unable to use the tool correctly, but estimates using the tool were closer to the true estimate. These findings suggest that even in a population more educated than the average U.S. citizen unrestricted internet searching often leads to poor estimates of survival, but nomograms can aid people in estimating survival rates. Clinicians should consider guiding patients to appropriate online health resources so that patients can obtain more accurate information and make informed decisions.

Alas, it is hard to know what to make of such data. Your sitemaster is well aware that scientific and mathematical education standards in the USA are not good, but what does this tell us about the standard of a university education?

The Kattan nomograms have been carefully presented on the MSKCC web site to make them pretty simple to use. And your sitemaster is as sure as he can be that the pathology report given to the participants would also have been about as straightforward as it could be! One would have hoped that most participants who had received a university education would have been able to get an answer that was at least in the ballpark after being shown where to find the right nomogram to use.

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