Exposed group Non-exposed group RR P value
Frequency (%) 95% CI Frequency (%) 95% CI
Incidence rate of PONV Sex
M 6(33.33) 21.35, 42.57 15(36.47) 29.39, 48.87 2.09 0.4
F 18(66.67) 47.05, 82.68 25(63.53) 50.47, 81.09    
Age Grouped
20-49 14(68.42) 49.47, 84.33 29(59.28) 41.36, 79.14 2.06 0.04
>49 6(31.58) 24.01, 43.47 13(40.72) 28.36, 57.58    
Type of anaesthesia
General 11 (48.39) 32.54, 60.14 18(47.37) 34.03, 59.57 0.99 0.47
Spinal 12(51.61) 39.35, 70.20 20(52.63) 36.14, 64.07    
Table 4: Association between type of anesthesia, sex, age-grouped and incidence rate of PONV in Ayder referral hospital Mekelle, northern Ethiopia, 2013.