162 Opioid prescribing and opioid-induced neurotoxicity in the palliative care setting: a single-centre observational study

<h3>Introduction</h3> Opioid-induced neurotoxicity (OIN) manifests with hypersomnolence, delirium, hallucinations, hyperalgesia and myoclonus. It impacts negatively on symptom control and quality of life. Diagnosing OIN is challenging due to overlapping differential causes of these presentations and a lack of standardised criteria. In addition, the aetiology and risk factors for OIN are not fully understood. This study aims to identify the prevalence, symptoms, and risk factors of OIN in a palliative care department in the United-Kingdom. <h3>Methods</h3> We conducted a single-centre observational study involving 85 patients reviewed by the palliative care team on February 1, 2024. Patient demographics, opioid prescriptions, and clinical features of OIN were recorded and analysed. OIN diagnosis was based on recorded clinical presentation and statistical analyses were performed to identify significant risk factors. <h3>Results</h3> Among the 85 patients, 76 (90%) were prescribed opioids, with 59 (69%) having taken opioids within 24 hours. Sixteen (27%) of these patients exhibited OIN symptoms. Significant risk factors included higher doses of background opioids (77 mg/24h vs. 18 mg/24h, p&lt;0.0001) and PRN opioids (39 mg/24h vs. 6 mg/24h, p&lt;0.0001), and frequent use of PRN opioids (3.1/24h vs 1.4/24h, p&lt;0.01). More patients with OIN had been prescribed oxycodone over other opioids (p=0.08), indicating a trend worth further investigation. <h3>Conclusions</h3> Hypersomnolence, cognitive changes, and hyperalgesia are key indicators of OIN. Our study confirms that higher doses of both background and PRN opioids, as well as higher frequency of PRN opioids, are significant risk factors for OIN. Lower doses than expected were linked with OIN and oxycodone conferred a higher risk. In keeping with this, we challenge the concept of a safe dose or safer opioid. These findings underscore the need for vigilant screening and tailored opioid management in this patient population. Further research with larger cohorts is warranted to validate these results.