OBJECTIVES: Generic health-related quality of life (HRQoL) instruments are often used together and interchangeably in economic evaluations. Earlier studies have shown that EQ-5D-3L and 15D do not measure health similarly in same patients. This study compared the performance of EQ-5D-5L and 15D in breast cancer patients before and after surgery.

METHODS: Patients diagnosed with breast cancer in Helsinki University Central Hospital in 2014 completed both instruments at admission and six months after the surgery (n=95). The 15D and EQ-5D-5L scores were calculated at baseline and at 6 months, and the change in HRQoL was calculated for each individual. The UK value set was used for the EQ-5D-5L and Finnish value set for the 15D. The agreement between the instruments was examined.

RESULTS: The study included 152 breast cancer patients of whom 95 responded to HRQoL surveys (mean age 60y; all female; 97% with no metastasis; 29% underwent total mastectomy).The baseline HRQoL was 0.92 by 15D and 0.86 by EQ-5D-5L, and the HRQoL after surgery was 0.88 and 0.80, respectively. During the six-month follow-up the HRQoL decreased by 0.04 by 15D and 0.06 by EQ-5D-5L. Higher correlation between the two instruments was detected for the patients with total mastectomy (pearson corr.coeff. 0.811) than for the patients with breast conserving surgery (pearson corr.coeff. 0.513).

CONCLUSIONS: This study is one of the first studies to compare 15D and EQ-5D-5L. According to the results, breast cancer patients’ HRQoL measured by 15D offers slightly higher HRQoL values and the change in HRQoL during the follow-up is smaller. The two instruments correlated fairly with each other and lead to different estimates concerning the number of QALYs gained.