Prevalence and Predictors of Early Response to Adjunct Methadone for Cancer-Related Pain in Palliative Care Patients—A Retrospective Study

<b><i>Background:</i></b> Adjunct methadone has been used previously for cancer-related pain, but evidence on predictors for early response remains limited. <b><i>Objective:</i></b> Identify the prevalence and predictors of early adjunct methadone response in palliative care patients. <b><i>Design:</i></b> Retrospective cohort study. <b><i>Settings/Subjects:</i></b> Patients who initiated adjunct methadone from 2022 to 2024. <b><i>Measurement:</i></b> Univariate and multivariate Poisson regression identified prevalence and predictors of early response. <b><i>Results:</i></b> Among 42 patients, 28 (67%) achieved early response. They had higher baseline oral morphine equivalents, higher starting methadone doses, and shorter days to first titration (<i>p</i> < 0.05). Predictors included metastatic cancer (RR 3.30, <i>p</i> = 0.005), higher performance status (RR 2.58, <i>p</i> = 0.033), methadone daily dose >5 mg (RR 3.91, <i>p</i> = 0.013), lower baseline pain scores (RR 0.78, <i>p</i> = 0.025), and preserved liver function (RR 4.32, <i>p</i> = 0.009). <b><i>Conclusion:</i></b> Metastatic cancer patients with high performance status without liver damage may benefit from a higher, proactively titrated starting dose of adjunct methadone.