The association between different opioid doses and the survival of advanced cancer patients receiving palliative care

Background: Concerns that opioids may hasten death can be a cause of the physicians' reluctance to prescribe opioids, leading to inadequate symptom palliation. Our aim was to find if there was an association between different opioid doses and the survival of the cancer patients that participated in our palliative care program. Methods: A retrospective study was conducted at Ramathibodi Hospital, Bangkok between January 2013 and December 2015. All of the cancer patients that were referred to palliative care teams by their primary physicians were included in the study. The study data included the patients' demographics, disease status, comorbidities, functional status, type of services, cancer treatments, date of consultation, and the date of the patient's death or last follow-up. The information concerning opioid use was collected by reviewing the medical records and this was converted to an oral morphine equivalent (OME), following a standard ratio. The time-varying covariate in the Cox regression analysis was applied in order to determine the association between different doses of opioids and patient survival. Results: A total of 317 cancer patients were included in the study. The median (IQR) of the OME among our patients was 6.43 mg/day (0.53, 27.36). The univariate Cox regression analysis did not show any association between different opioid doses (OME ≤ 30 mg/day and > 30 mg/day) and the patients' survival (p = 0.52). The PPS levels (p < 0.01), palliative care clinic visits (HR 0.32, 95%CI 0.24-0.43), home visits (HR 0.75, 95%CI 0.57-0.99), chemotherapy (HR 0.32, 95%CI 0.22-0.46), and radiotherapy (HR 0.53, 95%CI 0.36-0.78) were identified as factors that increased the probability of survival. Conclusions: Our study has demonstrated that different opioid doses in advanced cancer patients are not associated with shortened survival period.