Estimating Utilities / Disutilities for High Risk Metastatic Hormone-Sensitive Prostate Cancer (MHSPC) and Treatment-Related Adverse Events

OBJECTIVES: Patients with metastatic hormone-sensitive prostate cancer (mHSPC) have widespread disease and are responsive to hormone therapy. Patients classified as 'high-risk* have more aggressive disease (at least two of the following: Gleason score ≥8; ≥3 bone lesions; visceral metastasis). Symptoms of mHSPC and treatment burden can substantially impact patients' health-related quality of life (HRQL), however, health utility data in this setting are scarce. This study aimed to capture UK societal utility values for high-risk mHSPC and burdensome treatment-related adverse events (AEs). METHODS: Literature review and interviews with mHSPC patients (n=4) and oncology specialists (n=5) informed AE selection and health-state wording. Three base-states described a high-risk mHSPC patient: receiving androgen deprivation therapy (ADT) [BS1]; receiving docetaxel+ADT [BS2]; completed docetaxel treatment, still receiving ADT [BS3]. Descriptions of six severe AEs were combined with BS2. Health-states were validated with additional oncology specialists (n=6) and piloted with UK participants (cognitive debrief). A UK general public sample (n=200) valued health states using visual analogue scale (VAS) rating and Time Trade-Off (TTO) interview methods. Disutility of AEs on BS2 were calculated using Generalised Estimating Equation (GEE) model to account for correlating data. RESULTS: Mean TTO values for BS1-3 were 0.71 (SD=0.26), 0.63 (SD=0.29) and 0.68 (SD=0.26) and for BS2+AEs were 0.58 (fluid retention), 0.58 (alopecia), 0.54 (fatigue), 0.48 (reduced immunity), 0.41 (nausea+vomiting), and 0.40 (diarrhoea). Subtraction of means showed BS2+diarrhoea (-0.23) had largest decline in mean utility. GEE model found significant disutility for all AEs, with BS2+nausea+vomiting having the largest impact (GEE model coefficient -0.21; CI: -0.24, -0.16). CONCLUSIONS: In this study, utility values across mHSPC health-states showed a clinically plausible trend and significant impact of AEs, underlining the importance of accounting for impaired HRQL when assessing treatments for mHSPC. Disutility weights associated with severe AEs quantify their HRQL impact for use within economic modelling.