Effectiveness of Opioid Switching in Advanced Cancer Pain: A Prospective Observational Cohort Study

SIMPLE SUMMARY: Opioid switching is the practice of substituting one opioid for another to improve pain relief or reduce adverse effects. This study aimed to examine pain and adverse event outcomes in people with advanced cancer pain, comparing those who undergo opioid switching with a control group, using multidimensional pain and standardized adverse event recording to add toward the limited data on this common practice. We found that compared to the control group, opioid switching reduced pain (worst, average, now) (p < 0.05), uncontrolled breakthrough pain (a 3-fold reduction, p = 0.008), and psychological distress (48% to 16%, p < 0.005). This study demonstrates that opioid switching is effective at reducing pain, adverse effects, and psychological distress to satisfactory levels of symptom control within 1 week in a population with advanced cancer pain. The use of multidimensional tools and standardized reporting further adds to the quality of evidence supporting opioid switching practice. ABSTRACT: Opioid switching is a common practice of substituting one opioid for another to improve analgesia or adverse effects; however, it has limited evidence. This study aimed to examine the effectiveness of opioid switching in advanced cancer. This multi-center prospective cohort study recruited patients assessed to switch opioids (opioid switch group) or to continue ongoing opioid treatment (control group). Clinical data (demographics, opioids) and validated instruments (pain and adverse effects) were collected over two timepoints seven days apart. Descriptive analyses were utilized. Non-parametric tests were used to determine differences. Fifty-four participants were recruited (23 control group, 31 switch group). At the follow-up, opioid switching reduced pain (worst, average, and now) (p < 0.05), uncontrolled breakthrough pain (3-fold reduction, p = 0.008), and psychological distress (48% to 16%, p < 0.005). The switch group had a ≥25% reduction in the reported frequency of seven moderate-to-severe adverse effects (score ≥ 4), compared to a reduction in only one adverse effect in the control group. The control group experienced no significant pain differences at the follow-up. Opioid switching is effective at reducing pain, adverse effects, and psychological distress in a population with advanced cancer pain, to levels of satisfactory symptom control in most patients within 1 week.