Frequency, Rationale, and Doses for Opioid Switching in Advanced Cancer: A Longitudinal Cohort Study.

Abstract

Pain is common in advanced cancer, and many people require opioid switching to achieve adequate analgesia. However, longitudinal patterns of switching across the complete illness trajectory remain poorly characterised. This study describes the incidence, indications, dose Sthresholds, and prescribing patterns of opioid switching from advanced cancer diagnosis to death. This retrospective cohort study analysed opioid prescribing data for 200 adults with advanced cancer from diagnosis to death. Prescribing data were converted to standardised oral morphine equivalent daily dose (oMEDD). Switching frequency, dose thresholds, duration of opioid use, documented indications, and prescriber patterns were analysed using descriptive statistics. Opioid switching occurred in 58% of patients (n=116), with some requiring up to four switches. Each successive switch occurred after substantial dose escalation during treatment on a given opioid, where starting doses of each successive switch approximately doubled: 20mg oMEDD for the first opioid, 30mg at first switch, 60mg at second, and 180mg at third switch. Median duration on each opioid progressively shortened with each switch: 39 days (IQR 9-98), 25 days (IQR 6-103), and 18 days (IQR 5-53) for the first, second, and third switchess respectively. Inadequate analgesia was the predominant indication (58% of switches). Palliative care clinicians initiated an increasing proportion of switches (31% of first opioids; 89% of third). Opioid switching is common across the advanced cancer trajectory, characterised by progressive dose escalation and shortening duration of use with each successive switch. These findings highlight the importance of access to multiple opioid options and timely specialist palliative care involvement.