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Alex Konstantatos Matthew Chan Margaret Angliss

A PROSPECTIVE COHORT OF OPIOID USE, EFFICACY AND SENSITIVITY IN A GROUP OF CHINESE AND AUSTRALIAN PATIENTS HAVING MAJOR SURGERY. Alex Konstantatos Matthew Chan Margaret Angliss. OPIOID COHORT. Hypothesis

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Alex Konstantatos Matthew Chan Margaret Angliss

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  1. A PROSPECTIVE COHORT OF OPIOID USE, EFFICACY AND SENSITIVITY IN A GROUP OF CHINESE AND AUSTRALIAN PATIENTS HAVING MAJOR SURGERY Alex Konstantatos Matthew Chan Margaret Angliss

  2. OPIOID COHORT Hypothesis • People of Chinese Ethnicity have less opioid requirement after major surgery compared to Caucasian Australians because of increased efficacy and increased sedation in Chinese

  3. OPIOD COHORT: METHODOLOGY • Prospective evaluation of two groups of patients having elective major surgery involving open abdominal incision: 68 Chinese patients (Prince of Wales Hospital Hong Kong ) 68 Caucasian Australian patients (Alfred Hospital. Melbourne, Australia)

  4. OPIOD COHORT: METHODOLOGY INCLUSION CRITERIA • Age 18-80 • Racial features (Asian or Caucasian) • Spent most of life in the relevant country (Asians-Hong Kong/China, Caucasians/Australia) • Planned general anaesthesia +/- N2O, intraoperative morphine and postoperative PCA infusion therapy with morphine • Able to understand principles of effective use of PCA • No contraindication to NSAID or paracetamol

  5. OPIOD COHORT: METHODOLOGY EXCLUSION CRITERIA • History Persistent Pain • Opioid use up to 2 weeks prior to surgery • Renal or Hepatic impairment • Strong preference for regional analgesia or LA infiltration • Use of ketamine

  6. OPIOD COHORT: METHODOLOGY PREOPERATIVE SURVEY AND EDUCATION • Participants surveyed in native language about attitudes and understanding of opioids • Participants and Carers educated in native language about optimal use of PCA infusion for effective pain relief

  7. OPIOD COHORT: METHODOLOGY PERIOPERATIVE ANALGESIA • All subjects administered Morphine plus single dose of NSAID in theatre and prescribed Morphine PCA postoperatively for 72 hours • Patients with severe postoperative pain allowed paracetamol if prescribed by independent pain physician, data collection continued in this group • Opioid related side effects treated standardized therapies e.g. 5HT3 inh for PONV, antihistamine for itch

  8. OPIOD COHORT: METHODOLOGY OUTCOME MEASURES PRIMARY • 72 hour postoperative opioid consumption, including BMI adjusted opioid consumption SECONDARY • Pain intensity ratings over 72 hours with coughing (NRS) • Incidence of sedation, PONV, itch, respiratory rate

  9. OPIOD COHORT: METHODOLOGY OTHER OUTCOME MEASURES • Demographics • Attitudes about opioids and postoperative pain management • N2O use and effect • Educational attainment • Satisfaction Rating • Pharmacogenetics: OPRM1 status

  10. OPIOID COHORT: RESULTS 1

  11. OPIOID COHORT: RESULTS II

  12. OPIOID COHORT: RESULTS • Similar numbers of male/females, age, incision length, duration and classification of procedure type, need for paracetamol • Chinese participants had significantly lower BMI, greater exposure to intraoperative nitrous oxide, more upper abdominal surgeries, • Caucasian Australians had higher educational attainment

  13. OPIOID COHORT: RESULTS • Mean IVME consumption at 72 hrs significantly less in Chinese 86.8 mg (71.8-101.8) compared to Caucasian Australians 132.5 mg (115.3-149.7); p<0.005 • Opioid consumption lower in Chinese at 24, 48 hrs • BMI adjusted opioid consumption was also significantly less in Chinese participants 3.8(3.1-4.5)versus 4.9 (4.2-5.6) (p<0.029)

  14. OPIOID COHORT: RESULTS • NRS pain scores were significantly higher in Chinese subjects * RMANOVA

  15. OPIOID COHORT: RESULTS OPIOID RELATED SIDE EFFECTS SEDATION Lower scores in Chinese at: 0-24hrs; p=0.02 24-48 hrs; p=0.049 48-72 hrs, p<0.005

  16. OPIOID COHORT: RESULTS OPIOID RELATED SIDE EFFECTS PONV No significant difference between Chinese and Caucasian Australians at: 0-24 hrs (P=0.94) 24-48 hrs (P=0.31) 48-72 hrs (P=0.35)

  17. OPIOID COHORT: RESULTS OPIOID RELATED SIDE EFFECTS ITCH Chinese participants had significantly higher itch at: 0-24 hrs (p=0.05) 24-48hrs (p=0.001) 48-72hrs (p=0.001)

  18. OPIOID COHORT: RESULTS SATISFACTION RATING Chinese participants rated their satisfaction with pain management significantly higher than Caucasian Australians; (p=0.009)

  19. OPIOID COHORT: RESULTS N2O identified as a significant covariate influencing opioid consumption (p=0.001) i.e. it accounted for part of the difference between Chinese and Caucasians Significant difference in opioid consumption BETWEEN CHINESE and CAUCASIANS still present in those NOT exposed to N2O (p=0.008)

  20. OPIOID COHORT: RESULTS PATTERNS WITHIN GROUPS EXPOSED TO N2O 1) Caucasian Australians with N2O had SIMILAR opioid (p=0.76)and significantly LESS pain (p=0.04) compared to NO N2O Caucasian Australians 2) Chinese with N2O had SIMILAR opioid(p=0.68) and MORE pain but non-significant (p=0.88) compared to NO N2O. i.e. pattern of low opioid, higher pain intensity maintained Chinese having N2O reported greater incidence of vomiting which was non significant (p=0.2)

  21. OPIOID COHORT: RESULTS ATTITUDE SURVEY • Chinese participants were significantly more likely to expect severe pain after surgery and had a preference for others to control their pain management • Chinese patient carers were significantly more likely to express preference for their patients to control their own management • Neither Chinese nor Caucasian Australian participants nor their carers feared the subjects were at risk of opioid addiction

  22. OPIOID COHORT: CONCLUSIONS • Chinese patients after major surgery use less opioid and rate their pain intensity higher compared with Caucasian Australians and are more satisfied with their pain management • Chinese patients experienced less sedation in the setting of using significantly less morphine • Explanations for this are multifactorial and are explained in part by greater susceptibility to itch, more frequent exposure to nitrous oxide, greater preoperative expectation of severe pain, and a desire for less autonomy among the Chinese participants compared with Australian Caucasians.

  23. OPIOID COHORT: CONCLUSIONS GENETICS • Complex and multifaceted, we did not have enough power to confidently analyse genetic factors but noted some trends OPRM1( mu receptor variation) • GG variant present in good numbers in both populations. • Non-significant increase in opioid consumption among Chinese participants comparing AA and GG (p=0.05) • No significant differences in NRS pain among Chinese participants comparing AA and GG • No significant differences in opioid consumption or NRS pain among Caucasian Australians

  24. OPIOID COHORT: CONCLUSIONS • A patient’s experience of Pain after surgery is a balance between the efficacy and side effects of therapy and is influenced by their beliefs which can reflect ethnicity. Clinicians too often focus on pain scores alone.

  25. THANKS Matthew Chan Marg Angliss Paul Myles

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