Health-state utility of patients with HER2-positive breast cancer in Vietnam: A multicenter cross-sectional study.

Background: Patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer may have poor prognoses and short overall and disease-free survival. Most previous studies focused on assessing the quality of life and health-state utility of the general population of breast cancer patients. The number of studies for HER2-positive breast cancer patients is negligible. This study investigated the health-state utility and its associated factors among Vietnamese patients with HER2-positive breast cancer.

Methods: We conducted face-to-face interviews with 301 HER2-positive breast cancer patients to collect data. Their health-state utility was measured via the EQ-5D-5L instrument. The Mann-Whitney U and Kruskal-Wallis tests were employed to compare the differences in utility scores between two groups and among three groups or more, respectively. Factors associated with patients' heath-state utility were identified via Tobit regression models.

Results: Pain/discomfort (56.1%) and anxiety/depression (39.5%) were the two issues that patients suffered from the most, especially among metastatic breast cancer patients. The severity of distress (depression, anxiety, and stress) in patients was relatively mild. Of 301 patients, their average utility score was 0.86±0.17 (range: 0.03-1.00), and the average EQ-visual analogue scale (VAS) score was 69.12±12.60 (range: 30-100). These figures were 0.79±0.21 and 65.20±13.20 for 102 metastatic breast cancer patients, significantly lower than those of 199 non-metastatic cancer patients (0.89±0.13 and 71.13±11.78) (p<0.001), respectively. Lower health-state utility scores were significantly associated with older age (p = 0.002), lower education level (p = 0.006), lower monthly income (p = 0.036), metastatic cancer (p = 0.001), lower EQ-VAS score (p<0.001), and more severe level of distress (p<0.001).

Conclusions: Our findings showed a significant decrement in utility scores among metastatic breast cancer patients. Patients' health-state utility differed by their demographic characteristics (age, education level, and income) and clinical characteristics (stage of cancer and distress). Their utility scores may support further cost-effectiveness analysis in Vietnam.