Utility assessment
Outcomes were measured as quality-adjusted life years (QALYs), which is used to measure a disease burden, including both the effect on life quality and the quantity of life lived. Life quality is represented by utility weights given for each health state, ranging from 1 (best attainable health) to 0 (death). The utility values of the different health states were based on the study of Venkatesh et al.3 We considered the utility value of patients with lrPTMC under AS as 0.88. This represents a disutility difference, e.g., lower quality-of-life, of AS compared to disease-free state post-HT, driven mainly from studies conducted in prostate cancer – another malignancy that can be treated by active surveillance. We have also considered a range of 0.88 to 1 in the sensitivity analysis, as utility of 1 was suggested in other studies.17