Table 2.

Comparison of primary end points 1 and 2.

Studies	Difference in mean percentage change in NPRS score or visual analog pain scale			Number and percentage of participants who have a reduction in NPRS score of more than 30% at the end of trial, and the risk ratio			Number and percentage of participants who have reduction in NPRS score of more than 50% at the end of trial, and the risk ratio
	Treatment	Control	Difference	Treatment	Control	Risk ratio	Treatment	Control	Risk ratio
Backonja et al., 2008	-29.9 (-34.00 to -25.79)	-20.4 (-24.61 to -16.19)	-9.5 (-15.47 to -3.61)	91 (44%)	69 (33%)	1.51 (1.00 to 2.27)	N/A	N/A	N/A
Webster et al., 2010a	-25.0 (-29.02 to -20.98)	-14.7 ± 3.51	-10.3	83 (37%)	22 (29%)	0.92	55 (25%)	8 (10%)	2.84
Webster et al., 2010b	-36.6 (-44.02 to -29.19)	-32.3 (-42.63 to -22.05)	-4.3	50 (49%)	26 (49%)	1.00	40 (39%)	19 (36%)	5.96
Irving et al., 2011	-32.3 (-36.49 to -28.12)	-25.0 (-29.29 to -20.76)	-7.3	100 (47%)	72 (35%)	1.64	64 (30%)	43 (21%)	1.62
Watson et al., 1993	-15.0	-5.2	-9.8	N/A	N/A	N/A	N/A	N/A	N/A
Bernstein et al., 1989	-30	1	-31	N/A	N/A	N/A	N/A	N/A	N/A

% (95% confidence interval), p-value; %, p-value.

There were two different sets of data in Watson et al. (1993)—patients who have PHN for longer than 12 months, and patients who have PHN for longer than 6 months. The data shown was obtained from patients who have PHN for longer than 12 months.