Your Medical Mind_ How to Decide What Is Right for You - Jerome Groopman [113]
94 Among the many studies on complications from treatment of prostate cancer, the reader may find these most relevant to the issues that men face: Shilajit D. Kundu et al., “Potency, continence and complications in 3,477 consecutive radical retropubic prostatectomies,” Journal of Urology 172 (2004), pp. 2227–2231; David F. Penson et al., “5-year urinary and sexual outcomes after radical prostatectomy: Results from the prostate cancer outcomes study,” Journal of Urology 173 (2005), pp. 1701–1705; Mark S. Litwin et al., “Quality of life after surgery, external beam irradiation, or brachytherapy for early-stage prostate cancer,” Cancer 109 (2007), pp. 2239–2247; Juanita Crook et al., “Systematic overview of the evidence for brachytherapy in clinically localized prostate cancer,” CMAJ 164 (2001), pp. 975–981; Jerry D. Slater et al., “Proton therapy for prostate cancer: The initial Loma Linda University experience,” International Journal of Radiation Oncology, Biology, Physics 59 (2004), pp. 348–352; Michael L. Blute, “Radical prostatectomy by open or laparoscopic/robotic techniques: An issue of surgical device or surgical expertise?” JCO 26 (2008), pp. 2248–2249; Jim C. Hu et al., “Comparative effectiveness of minimally invasive vs. open radical prostatectomy,” JAMA 302 (2009), pp. 1557–1564.
96 For the marked limitations of using methods like standard gamble to determine treatment preferences, see Sara J. Knight et al., “Pilot study of a utilities-based treatment decision intervention for prostate cancer patients,” Clinical Prostate Cancer (September 2002), pp. 105–114.
Schwartz and Bergus point out that there is no standard definition of “perfect health” (Medical Decision Making: A Physician’s Guide [Cambridge, UK: Cambridge University Press, 2008]). The rating scale method between 0 as death and 100 as perfect health is usually taken as a percentage, so that if someone was to designate a value of 50, this would be 50 percent, or 0.50. One of the major problems with the linear rating scale is that it is “arbitrary,” as Schwartz and Bergus point out: “When a patient indicates that blindness should receive a value of 50, there is no behavioral interpretation for that value—it means nothing beyond ‘a rating of 50.’”
In the time trade-off method, patients are told their predicted life expectancy based on actuarial data and then asked to imagine that they will spend the rest of their lives in some imperfect health state and to consider what that would be like. Then they are asked to imagine that a new treatment can restore them to perfect health but will shorten their life by a given amount. Would they take the treatment ? If so, how many years are worth trading for perfect health? The trade-offs continue until the patients are indifferent between the prospect of a shorter lifetime with perfect health and their full life span with imperfect health. At that point, the duration in perfect health is divided by the duration in imperfect health and a percentage obtained; this percentage is used as the number for utility for the imperfect health state. For example, if a man has a life expectancy of seventy-eight years, and he is currently fifty-four years old, he can expect to live twenty-four more years. If he is diabetic, he is asked to imagine twenty-four years with diabetes in his current health state and then given the choice between twenty-four years with diabetes or twelve years in perfect health followed by death. He prefers twenty-four years with diabetes, so he is then offered a choice between twenty-four years with diabetes and twenty-three years in perfect health, and he prefers twenty-three years in perfect health. He is then offered a choice between twenty-four years with diabetes and twenty years in perfect health, and he prefers twenty-four years with diabetes. When he is offered twenty-four years with diabetes and twenty-two years in perfect health,