THE EFFECT OF ETHNICITY ON THE INCIDENCE OF POSTOPERATIVE NAUSEA AND VOMITING IN MODERATE TO HIGH RISK PATIENTS UNDERGOING GENERAL ANESTHESIA IN SOUTH AFRICA: A CONTROLLED OBSERVATIONAL STUDY.

BACKGROUND

We conducted this prospective controlled observational study to compare the effect of ethnicity on the risk of postoperative nausea and vomiting (PONV) between moderate to high-risk African and non-African patients undergoing general anesthesia.

METHODS

Using Apfel score risk factors and predicted length of surgery (>30 minutes), 89 moderate to high risk patients undergoing general anesthesia were recruited in a university hospital between March 2009 and November 2010. Thirty patients in the non-African group and 59 patients in the African group were allocated using an ethnicity self identification questionnaire. Intraoperative anesthesia was standardized. PONV was assessed at 0 minutes, 15 minutes, 90 minutes, 180 minutes, and 24 hours. Generalized linear mixed effects models was used to determine the effect of ethnicity on PONV.

RESULTS

Despite similar Apfel scores, cumulative incidence of postoperative nausea was higher in the non-African group at 0 minutes (46.67% vs 22.03%, 0.019), 15 minutes (70% vs 23.73%, p<0.001) and 90 minutes (36.67% vs 16.95%, = 0.04). The non-African group had more episodes of vomiting over 24 hours (13.33% vs 1.69%, = 0.055). Non-Africans had a 25 times higher reported nausea incidence than Africans over 24 hours.

CONCLUSION

The incidence of PONV in non-Africans is significantly higher than in Africans. Non-African ethnicity is an independent risk factor for PONV. Current risk prediction models may be limited in multi-ethnic populations and further investigations are warranted to examine ethnicity as a risk factor.