Background: Continuous deep sedation (CDS) before death is a form of palliative sedation therapy that has become a focus of strong debate, especially with respect to whether it shortens survival. We aimed to examine whether CDS shortens patient survival using the propensity score-weighting method, and to explore the effect of artificial hydration during CDS on survival. Methods: This study was a secondary analysis of a large multicentre prospective cohort study that recruited and followed up patients between Sept 3, 2012, and April 30, 2014, from 58 palliative care institutions across Japan, including hospital palliative care settings, inpatient palliative care units, and home-based palliative care services. Adult patients (aged ≥20 years) with advanced cancer who received care through the participating palliative care services were eligible for this secondary analysis. Patients with missing data for outcome variables or who lived for more than 180 days were excluded. We compared survival after enrolment between patients who did and did not receive CDS. We used a propensity score-weighting method to control for patient characteristics, disease status, and symptom burden at enrolment. Findings: Of 2426 enrolled patients with advanced cancer, we excluded 289 (12%) for living longer than 180 days and 310 (13%) with missing data, leaving an analysis population of 1827 patients. 269 (15%) of 1827 patients received CDS. Unweighted median survival was 27 days (95% CI 22-30) in the CDS group and 26 days (24-27) in the no CDS group (median difference -1 day [95% CI -5 to 4]; HR 0·92 [95% CI 0·81-1·05]; log-rank p=0·20). After propensity-score weighting, these values were 22 days (95% CI 21-24) and 26 days (24-27), respectively (median difference -1 day [95% CI -6 to 4]; HR 1·01 [95% CI 0·87-1·17]; log-rank p=0·91). Age (pinteraction=0·67), sex (pinteraction=0·26), performance status (pinteraction=0·90), and volume of artificial hydration (pinteraction=0·14) did not have an effect modification on the association between sedation and survival, although care setting did have a significant effect modification (pinteraction=0·021). Interpretation: CDS does not seem to be associated with a measurable shortening of life in patients with advanced cancer cared for by specialised palliative care services, and could be considered a viable option for palliative care in this setting. Funding: Japanese National Cancer Center Research and Development Fund.
ASJC Scopus subject areas