Men?s preferences for treatment of early stage prostate cancer: Results from a discrete choice experiment, CHERE Working Paper 2006/14

Prostate cancer is the most common cancer in men in Australia; each year over 10,000 Australians are diagnosed with this disease. There are a number of treatment options for early stage prostate cancer (ESPC); radical prostatectomy, external beam radiotherapy, brachytherapy, hormonal therapy and combined therapy. Treatment can cause serious side-effects, including severe sexual and urinary dysfunction, bowel symptoms and fatigue. Furthermore, there is no evidence as yet to demonstrate that any of these treatments confers a survival gain over active surveillance (watchful waiting). While patient preferences should be important determinants in the type of treatment offered, little is known about patients? views of the relative tolerability of side effects and of the survival gains needed to justify these. To investigate this, a discrete choice experiment (DCE) was conducted in a sample of 357 men who had been treated for ESPC and 65 age-matched controls. The sample was stratified by treatment, with approximately equal numbers in each treatment group. The DCE included nine attributes: seven side-effects and two survival attributes (duration and uncertainty). An orthogonal fractional set of 108 scenarios from the full factorial was used to generate three versions of the questionnaire, with 18 scenarios per respondent. Multinomial logit (MNL) and mixed logit (MXL) models were estimated. A random intercept MXL model provided a significantly better fit to the data than the simple MNL model, and adding random coefficients for all attributes dramatically improved model fit. Each side-effect had a statistically significant mean effect on choice, as did survival duration. Most attributes had significant variance parameters, suggesting considerable heterogeneity among respondents in their preferences. To model this heterogeneity, we included men?s health-related quality of life scores following treatment as covariates to see whether their preferences were influenced by their previous treatment experience. This study demonstrate how DCEs can be used to quantify the trade-offs patients make between side-effects and survival gains. The results provide useful insights for clinicians who manage patients with ESPC, highlighting the importance of patient preferences in treatment decisions.