Introduction The role of hydration in causing or alleviating suffering in advanced cancer is poorly understood. Bioelectrical impedance analysis (BIA) is an accurate validated method of assessing hydration status. Previous BIA research demonstrates significant relationships with hydration status, symptoms, and survival in advanced cancer. Further work is needed to study these associations in the dying.

Aims To evaluate hydration and its relationship with clinical symptoms in dying cancer patients.

Methods We conducted an observational study of people with advanced cancer in three centres (two hospices and one hospital palliative care inpatient unit). We used an advance consent methodology to conduct hydration assessments participants with advanced cancer who were dying. We recorded hydration status (via BIA Impedance index: Height – H2/Resistance – R), symptoms, physical signs, and quality-of-life assessments.

Results One hundred and twenty-five people participated (males n=74 (59.2%), females, n=51 (40.8%). We repeated assessments in 18 (14.4%) participants when they were dying. Hydration status (H2/R) of dying patients was not significantly different compared to baseline assessments (n= 18, M= 49.55, SD= 16.00 vs. M= 50.96, SD= 12.13; t(17)= 0.636, p = 0.53). Backward linear regression demonstrated that ‘more hydration’ (increased H2/R) was associated with oedema (Beta= 0.514, p<0.001) and increased pain (Beta = 0.156, p=0.039). ‘Less hydration’ (reduced H2/R) was associated with female gender (Beta = -0.371, p<0.001), increased anxiety (Beta = -0.135, <0.001), increased physical signs (combination of dry mouth, dry axilla, sunken eyes – Beta = -0.204, p<0.001), and increased breathless (Beta = -0.180, p<0.014).

Conclusions Hydration status was associated with physical signs and symptoms in advanced cancer. No significant difference in hydration status was observable in dying patients compared to baseline. Further studies can use the outcomes of this work to develop and validate hydration assessment methods to improve personalised management and communication with patients and caregivers.

Impact Hydration status in advanced cancer is associated with clinical outcomes, which provides the poissibility for researchers and clinicians to develop personalised approaches for clinical management, and communication, to improve hydration management in palliative care. This study highlights the potential to use bioimpedance for non-invasive hydration assessment in palliative care, demonstrating possibilities in research and clinical practice.