A prospective cohort study comparing early opioid requirement between Chinese from Hong Kong and Caucasian Australians after major abdominal surgery.

BACKGROUND The relationship between ethnicity and early opioid consumption is not well understood. Our prospective cohort study tested whether Chinese patients in Hong Kong require less opioid after major abdominal surgery compared with Caucasian patients in Australia. METHODS Matched cohorts of patients from Hong Kong (n=68) and Australia (n=68) were recruited. Patient attitudes and expectations to pain management documented. After operation, all patients received i.v. morphine using a patient-controlled analgesia device. Postoperative opioid consumption, pain intensity, and incidence of opioid-related side-effects were recorded. RESULTS The average (sd) opioid requirement (i.v. morphine equivalent) at 72 h after surgery was significantly less among Chinese patients [86.8 (62.6) mg (95% CI 71.8, 101.8)] compared with Caucasian patients [130.6 (71.9) mg, (P<0.0005) (95% CI 113.4, 147.8)]. Numeric rating scale pain score (0-10) was, however, higher in Chinese patients compared with Caucasian Australians, 5.3 (2.7) vs 4.4 (2.3) (P=0.029). The incidence of pruritus among Chinese patients was significantly higher than Caucasians at 24-48 h (P=0.001) and 48-72 h (P=0.001). Chinese patients also reported a strong preference for others to manage their pain, and their nurse carers were more likely to expect severe pain after surgery. CONCLUSIONS Chinese patients in Hong Kong required less opioid and experienced greater pain intensity and pruritus than Caucasian patients. Clinicians should consider differences in the side-effect profile of morphine and patient expectations related to pain control when planning postoperative analgesia for patients of Chinese ethnicity.