Increased incidence of postoperative infections during prophylaxis with cephalothin compared to doxycycline in intestinal surgery

Table 3 Relative risks, with 95% confidence intervals, of SSI for periods with cephalothin and metronidazole relative to periods with doxycycline and metronidazole

Patient group	Periods	Crude RR^a	95% CI	Adjusted RR^b	95% CI
Colorectal patients^c	2 versus 1 and 3	1.60	1.23, 2.09	1.61	1.22, 2.12
	2 versus 1	1.56	1.18, 2.06	1.57	1.18, 2.19
	2 versus 3	1.74	1.17, 2.60	1.74	1.15, 2.62
Gyneacology patients^d	2 and 3 versus 1	1.10	0.75, 1.62	0.98	0.64, 1.49

^a Calculated by using log-binomial regression models.
^b Adjusted for age, gender, surgical procedure, ASA score, emergency procedure, time of operation and operation time.
^c Period 1 was the first period of treatment with doxycycline and metronidazole. Period 2 was the period when cephalothin and metronidazole was used, and period 3 was the period when we returned to doxycycline and metronidazole.
^d Period 1 was the first period of treatment with doxycycline and metronidazole. Cephalothin and metronidazole was used throughout period 2 and 3 (i.e., did not return to doxycycline and metronidazole in period 3).

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