ESTIMATING TIME EQUIVALENTS FOR CANCER SIDE EFFECTS AMONG LUNG CANCER SURVIVORS AND CAREGIVERS: A DISCRETE-CHOICE EXPERIMENT

Purpose: While there is a growing literature on estimating the tradeoffs between the benefits and risk of cancer care, there is a paucity of literature exploring preferences for the collateral damage associated with long-time side effects. We estimated the treatment preferences of lung cancer survivors and caregivers and estimated the time equivalents for multiple domains of long-term side effects. 

Method: Through rigorous engagement of a national advisory board of lung cancer survivors, a discrete-choice experiment (DCE) was developed, pretested and piloted. The DCE was administered to lung cancer survivors and caregivers that attended a national summit. Respondents at the meeting completed 13 paired-comparison choice tasks described across six attributes: progression-free survival (PFS), short-term side effects, and physical, emotional, cognitive, and functional long-term side effects. A continuous preference model was estimated using mixed logit and, using PFS as the numeraire, the preference for avoiding the side-effects were estimated using their time equivalents by using maximum simulated likelihood.

Result: Of 114 survey participants, 102 (89.4%) completed all choice tasks - although no difference was identified between those who did not complete the task (p>0.05 for all observed characteristics). All attributes were statistically different form the null (p<0.001). Respondents valued a one-unit decrease in functioning the most, valuing it equivalent to extending PFS by 3.67 months. Changes in physical (2.34) and cognitive (2.29) were valued more than a composite of all short-term side effects (1.83). Heterogeneity analyses indicated that avoiding long-term side effects could be valued even more highly for some respondents. For example, accounting for preference heterogeneity, the 95% confidence interval for time equivalence of functional long-term side effects ranged from 0.62 up to 13.31 months.

Conclusion: While this small, retrospective study that focuses only on lung cancer has many limitations, the results indicate that avoiding the long-term side effects could have significant value, especially as many patients experience moderate long-term side effects across multiple domains.