Table 2.

Between-group comparisons of duration of analgesia

	Group R	Group RN	Group RK
Duration of analgesia, median (98.3% CI) (min)	320.0 (308.5–332.0)	829.5 (780.0–860.0)	820.0 (812.0–877.0)
Difference
Compared with group R (median) (98.3% CI), mina	NA	–492.0 (–526.8 to –459.0)	–513.0 (–539.2 to –489.4)
P valueb		P < 0.001	P < 0.001
Compared with group RN, median (98.3% CI) (min)a	NA	NA	–19.5 (–49.1 to 11.2)
P valueb			P = 0.83
Compared with group RK, median (98.3% CI) (min)a	NA	NA	NA
P valueb

NA not applicable, CI confidence interval, R ropivacaine, RN ropivacaine + nalbuphine, RK ropivacaine + ketorolac

^aConfidence intervals were calculated by Hodges-Lehmann estimation to estimate the median difference

^bP values were calculated using Kruskal–Wallis test