Opioid switching to improve delirium symptoms in patients with cancer: a systematic review

Delirium is a common and distressing symptom in patients with cancer, while opioids-which are essential in managing cancer pain-can cause delirium. Opioid switching is a widely used strategy for the management of opioid-induced delirium; however, its efficacy is yet to be verified. This systematic review aimed to determine opioid switching's efficacy and safety for managing opioid-induced delirium in patients with cancer.

This systematic review was conducted in accordance with the PRISMA guidelines. We searched four databases (PubMed, Cochrane Controlled Register of Trials, Cochrane Library, and Ichishi-Web) on September 6, 2023, with an updated PubMed search on October 20, 2024. Our review included studies on opioid switching for managing delirium in patients with cancer. If there were less than two randomized controlled trials (RCTs), we included observational studies. Data extraction and evaluation were independently conducted by two reviewers using the GRADE evaluation. The study protocol was registered (UMIN000051787).

The literature search identified seven observational studies without a control group; however, no RCTs were found. Four observational studies reported improvements in the severity of delirium symptoms. No study reported worsening pain or dyspnea after opioid switching. According to the GRADE framework, all outcomes were graded very low on certainty.

Although observational studies imply opioid switching's effectiveness for managing opioid-induced delirium in patients with cancer, there is a lack of RCTs and the level of evidence is very low. Thus, RCTs are warranted to confirm opioid switching's efficacy.