Patients' preferences for the management of non-metastatic prostate cancer: discrete choice experiment
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《英国医生杂志》
1 Centre for Health Economics, University of York, Heslington, York YO10 5DD, 2 Health Economics Facility, Health Services Management Centre, University of Birmingham, Birmingham B15 2RT, 3 Institute of Urology, Royal Free and University College Medical School, London W1P 7PN, 4 Meyerstein Institute of Oncology, Middlesex Hospital, London W1T 3AA
Correspondence: M Sculpher mjs23@york.ac.uk
Abstract
Several situations exist where patients face trade-offs between the risks and benefits of alternative therapies.1 The conservative management of men with organ confined or locally advanced prostate cancer is such a situation. Men diagnosed at a stage when radical treatments such as prostatectomy or radiotherapy are inappropriate face several treatment options, including watchful waiting or oral steroidal or non-steroidal antiandrogen monotherapy.2 Many patients choose castration, performed medically rather than surgically. Alternatively, there is the option of antiandrogen treatment combined with medical or surgical castration.
To make an informed choice, men need to be able to weigh up the slight differences in effectiveness of treatment against a spectrum of side effects associated with alternative strategies. For example, non-steroidal antiandrogen monotherapy offers potential advantages over castration for impotence, loss of libido, and hot flushes, but these may be achieved at the cost of an increased risk of gynaecomastia and breast pain.3
Individuals' preferences for alternative treatments need to be considered in the light of the attributes of the treatments. Discrete choice experimentation, an approach for elicitation of preferences, is now being used widely in health care.4 5 This approach identifies the key characteristics of alternative treatments, such as hot flushes, and selects a series of levels for each (for example, absent, mild, moderate). Respondents choose from several options, each of which details a series of attributes at different levels. The relative importance of attributes to individuals and the trade-offs made between them, can be assessed by changing the levels of the attributes and asking participants to make their choice again. Findings on the reliability and validity of discrete choice experimentation in healthcare settings are encouraging.6 7 We used discrete choice experimentation to elicit treatment related preferences in a sample of men with non-metastatic prostate cancer.
Methods
Between 24 May and 8 September 2000, we invited 180 men to participate in our study. Of these, 129 were interviewed. Participants were similar to those who declined for mean age and T stage at diagnosis. Table 2 shows the characteristics of the participants.
Table 2 Characteristics of men (n=129). Values are numbers (percentages) unless stated otherwise
Discrete choice experiment
Table 3 shows the results of the first part of the exercise. The coefficients for the unique attributes were all statistically significantly different from 0; negative values for libido, maintaining an erection, and physical energy indicate that the more severe the problems, the less likely the patient is to prefer that scenario; negative values for out of pocket expenses indicate that the higher the costs, the less likely the patient is to prefer that scenario. Positive values for life expectancy indicate that the greater the life expectancy the more likely the patient is to prefer that scenario. The only statistically significant interaction was between ability to maintain an erection and age; the positive value indicates that older men were less likely to be influenced by the ability to maintain an erection in choosing their preferred scenario.
Table 3 Results of first part of discrete choice exercise
Table 4 shows the results of the second part of the exercise, which also considered the unique attributes of diarrhoea, hot flushes, and breast tenderness. The coefficients for the attributes were all statistically significantly different from zero. Negative values for diarrhoea, hot flushes, and breast tenderness indicate that the more severe the problem the less likely the patient is to prefer that scenario. None of the interaction terms were statistically significantly different from zero.
Table 4 Results of second part of discrete choice exercise
Table 5 shows the marginal rates of substitution between life expectancy and other attributes—that is, how much life expectancy the men were willing to trade off to achieve an improvement by one level in one of the other attributes. For example, men were willing to trade off 1.8 months of life expectancy to change diarrhoea from a moderate to mild level or from mild to absent. Because the levels of severity differed between attributes, marginal rates of substitution between attributes should be compared with caution. The least important marginal rates of substitution were for hot flushes and the most important were for physical energy.
Table 5 Patients' marginal rates of substitution between life expectancy and other attributes
Discussion
Kassirer JP, Pauker SG. The toss-up. N Engl J Med 1981;305: 1467-9.
Adolfson J. The natural history of early prostate cancer and the impact of endocrine treatment. Eur Urol 1999;36(suppl 2): 3-8.
Iverson P, Tyrrell CJ, Kaisary AV, Anderson JB, Baert L, Tammela T, et al. Casodex (bicalutamide) 150-mg monotherapy compared with castration in patients with previously untreated nonmetastatic prostate cancer: results from two multicentre randomised trials at a median follow-up of 4 years. Urology 1998;51: 389-96.
Bryan S, Buxton M, Sheldon R, Grant A. Magnetic resonance imaging for the investigation of knee injuries: an investigation of preferences. Health Econ 1998;7: 595-604.
Ryan M, Farrar S. Using conjoint analysis to elicit preferences for health care. BMJ 2000;320: 1530-3.
Bryan S, Gold L, Sheldon R, Buxton M. Preference measurement using conjoint methods: an empirical investigation of reliability. Health Econ 2000;9: 385-95.
Bryan S, Parry D. Structural reliability of conjoint measurement in health care: an empirical investigation. Appl Econ 2001;34: 561-7.
Messing EN, Manola J, Sarosdy M, Wilding G, Crawford ED, Trump D. Immediate hormonal therapy compared with observation after radical prostatectomy and pelvic lymphadenectomy in men with node-positive prostate cancer. N Engl J Med 1999;341: 1781-8.
Blackard CE, Byar DP, Jordan WP Jr. Orchidectomy for advanced prostatic carcinoma. A re-evaluation. Urology 1973;1: 553-60.(Mark Sculpher, professor1)
Correspondence: M Sculpher mjs23@york.ac.uk
Abstract
Several situations exist where patients face trade-offs between the risks and benefits of alternative therapies.1 The conservative management of men with organ confined or locally advanced prostate cancer is such a situation. Men diagnosed at a stage when radical treatments such as prostatectomy or radiotherapy are inappropriate face several treatment options, including watchful waiting or oral steroidal or non-steroidal antiandrogen monotherapy.2 Many patients choose castration, performed medically rather than surgically. Alternatively, there is the option of antiandrogen treatment combined with medical or surgical castration.
To make an informed choice, men need to be able to weigh up the slight differences in effectiveness of treatment against a spectrum of side effects associated with alternative strategies. For example, non-steroidal antiandrogen monotherapy offers potential advantages over castration for impotence, loss of libido, and hot flushes, but these may be achieved at the cost of an increased risk of gynaecomastia and breast pain.3
Individuals' preferences for alternative treatments need to be considered in the light of the attributes of the treatments. Discrete choice experimentation, an approach for elicitation of preferences, is now being used widely in health care.4 5 This approach identifies the key characteristics of alternative treatments, such as hot flushes, and selects a series of levels for each (for example, absent, mild, moderate). Respondents choose from several options, each of which details a series of attributes at different levels. The relative importance of attributes to individuals and the trade-offs made between them, can be assessed by changing the levels of the attributes and asking participants to make their choice again. Findings on the reliability and validity of discrete choice experimentation in healthcare settings are encouraging.6 7 We used discrete choice experimentation to elicit treatment related preferences in a sample of men with non-metastatic prostate cancer.
Methods
Between 24 May and 8 September 2000, we invited 180 men to participate in our study. Of these, 129 were interviewed. Participants were similar to those who declined for mean age and T stage at diagnosis. Table 2 shows the characteristics of the participants.
Table 2 Characteristics of men (n=129). Values are numbers (percentages) unless stated otherwise
Discrete choice experiment
Table 3 shows the results of the first part of the exercise. The coefficients for the unique attributes were all statistically significantly different from 0; negative values for libido, maintaining an erection, and physical energy indicate that the more severe the problems, the less likely the patient is to prefer that scenario; negative values for out of pocket expenses indicate that the higher the costs, the less likely the patient is to prefer that scenario. Positive values for life expectancy indicate that the greater the life expectancy the more likely the patient is to prefer that scenario. The only statistically significant interaction was between ability to maintain an erection and age; the positive value indicates that older men were less likely to be influenced by the ability to maintain an erection in choosing their preferred scenario.
Table 3 Results of first part of discrete choice exercise
Table 4 shows the results of the second part of the exercise, which also considered the unique attributes of diarrhoea, hot flushes, and breast tenderness. The coefficients for the attributes were all statistically significantly different from zero. Negative values for diarrhoea, hot flushes, and breast tenderness indicate that the more severe the problem the less likely the patient is to prefer that scenario. None of the interaction terms were statistically significantly different from zero.
Table 4 Results of second part of discrete choice exercise
Table 5 shows the marginal rates of substitution between life expectancy and other attributes—that is, how much life expectancy the men were willing to trade off to achieve an improvement by one level in one of the other attributes. For example, men were willing to trade off 1.8 months of life expectancy to change diarrhoea from a moderate to mild level or from mild to absent. Because the levels of severity differed between attributes, marginal rates of substitution between attributes should be compared with caution. The least important marginal rates of substitution were for hot flushes and the most important were for physical energy.
Table 5 Patients' marginal rates of substitution between life expectancy and other attributes
Discussion
Kassirer JP, Pauker SG. The toss-up. N Engl J Med 1981;305: 1467-9.
Adolfson J. The natural history of early prostate cancer and the impact of endocrine treatment. Eur Urol 1999;36(suppl 2): 3-8.
Iverson P, Tyrrell CJ, Kaisary AV, Anderson JB, Baert L, Tammela T, et al. Casodex (bicalutamide) 150-mg monotherapy compared with castration in patients with previously untreated nonmetastatic prostate cancer: results from two multicentre randomised trials at a median follow-up of 4 years. Urology 1998;51: 389-96.
Bryan S, Buxton M, Sheldon R, Grant A. Magnetic resonance imaging for the investigation of knee injuries: an investigation of preferences. Health Econ 1998;7: 595-604.
Ryan M, Farrar S. Using conjoint analysis to elicit preferences for health care. BMJ 2000;320: 1530-3.
Bryan S, Gold L, Sheldon R, Buxton M. Preference measurement using conjoint methods: an empirical investigation of reliability. Health Econ 2000;9: 385-95.
Bryan S, Parry D. Structural reliability of conjoint measurement in health care: an empirical investigation. Appl Econ 2001;34: 561-7.
Messing EN, Manola J, Sarosdy M, Wilding G, Crawford ED, Trump D. Immediate hormonal therapy compared with observation after radical prostatectomy and pelvic lymphadenectomy in men with node-positive prostate cancer. N Engl J Med 1999;341: 1781-8.
Blackard CE, Byar DP, Jordan WP Jr. Orchidectomy for advanced prostatic carcinoma. A re-evaluation. Urology 1973;1: 553-60.(Mark Sculpher, professor1)