Table 4.

SSI analysis of available cases, stratified by sex

	Antibiotic Prophylaxis	Control group	P values	Absolute risk reduction	95% CI	Relative risk reduction (%)	NNTB (95% CI)
Analysis of available cases
	n=73	n=69
No of SSI	n=1	n=8
Incidence rate of SSI	1.4%	11.6%	P=0.015*	10.2%	2.2 to 18.2	87.9	9.8 (5.5 to 45.5)
Analysis of available cases stratified by sex
Male	n=33	n=44
Incidence rate of SSI	0% (n=0)	15.9% (n=7)	P=0.018*	15.9%	5.2 to 26.6	100	6.3 (3.8 to 19.2)
Female	n=40	n=25
Incidence rate of SSI	2.5% (n=1)	4.0% (n=1)	P=1.0*	1.5%	−7.6 to 10.6	37.5	66.7 (NNTH 13.2 to infinity to NNTB 9.4)

*P values are results of Fisher’s exact test.

NNTB, number needed to treat for benefit; NNTH, number needed to treat for harm; SSI, surgical site infection.