Purpose: Study utilized a time-trade-off (TTO) technique to elicit patient preferences for management of brain metastases in patients randomized to whole brain radiation treatment plus stereotactic radiosurgery (SW arm) versus stereotactic radiosurgery alone (SA arm).
Method: A TTO instrument with three time horizons (10, 5 , and 1-year) was developed to determine the time a patient is willing to trade off current health for a period of perfect health. Utilities were collected at baseline and predetermined intervals for 2 years. The utilities for baseline and the final visit (last visit prior to death or at end of study) were analyzed to determine if there were any differences based on treatment group and other co-variates, including demographics and medical history, using t-test and linear regression.
Result: The study population consisted of 58 patients, 30 (51.72%) male, 46 (79.31%) Caucasian, and mean age of 61.76 (SD: 10.99). There were 27 patients in the SW arm and 31 in the SA arm and the mean baseline utilities were 0.78 (SD: 0.29), 0.83 (SD: 0.27), and 0.88 (SD: 0.26), for the 10-year, 5-year, and 1-year timeframes respectively; the mean final utilities were 0.74 (SD: 0.33), 0.83 (SD: 0.28); and 0.87 (SD: 0.28), respectively. For the 58 patients, there was a stronger correlation between the 10-year and 5-year baseline utilities (R-squared: 0.80) and the 10-year and 5-year final utilities (R-squared: 0.70) than between the 10-year and 1-year (R-squared: 0.48 and 0.56) and the 5-year and 1-year utilities (R-squared: 0.58 and 0.69). Also, there was significant difference in the 10-year versus 5-year baseline and 10-year versus 5-year final utilities (p=0.0041; p=0.0003), the 10-year versus 1-year baseline and final utilities (p=0.0009; p<0.0001) and the 5-year versus 1-year at baseline only (p=0.0411). These data indicate that patients were adjusting the answers to the timeframe presented and the range of time traded was least in the 1-year timeframe. None of the co-variates tested resulted in a positive association, including the treatment group assignment.
Conclusion: Patients undergoing radiation treatment for brain metastases do not exhibit differences in preferences to treatment assignment. However, they adjust their responses to the timeframe presented, indicating the validity of using a TTO instrument with different timeframes to elicit utilities in a terminal ill study group.
Candidate for the Lee B. Lusted Student Prize Competition