Evaluation of the impact of CYP2D6 testing on outcomes in patients taking opioids

CYP2D6 affects metabolism of several opioids; however, the clinical impact of genetic variants on efficacy has limited evidence in large patient populations.

This study aims to assess the impact of CYP2D6 phenotype on pain response in an elective pharmacogenomics (PGx) screening population prescribed opioids.

A retrospective review was conducted on hospitalized patients with CYP2D6 genotyping, prescribed either codeine, tramadol, hydrocodone, or oxycodone within 24 months prior to PGx testing and through 36 months after results. Pain scores were abstracted on a 10-point analog scale and categorized into 3 cohorts (mild, moderate, and severe) based on their baseline pain score. Baseline pain score was measured within 30 min of each opioid dose administration. Percentage changes in pain scores from baseline to 6, 12, 24, and 48 hours following each respective opioid dose administration were analyzed. Morphine milligram equivalents (MME) were averaged amongst the days of opioid administration.

A total of 8062 patients were analyzed. Oxycodone was the most administered (4856, 41%). Mild pain cohort poor metabolizers (PMs) had significant increase in pain scores compared to normal metabolizers (NMs) at all hours from baseline (P < 0.001). PMs in moderate and severe pain cohorts had significantly decreased pain score reduction than NMs at all hours from baseline (P < 0.001). PMs had significantly higher MME compared to NMs in these cohorts (15 vs. 10, P < 0.001).

CYP2D6 PMs had significantly less pain score reduction. CYP2D6 genotyping can lead to effective use of opioids in pain management and may display greater impact on efficacy of oxycodone than previously studied. Full implication of PGx testing is limited by the study's retrospective nature. PMs across all pain intensity cohorts had significantly less reduction in pain scores from baseline compared to NMs (P < 0.05). These results encourage further investigation into prospective pre-emptive CYP2D6 testing regarding effective pain management by optimizing opioid administration.