Risk of surgical site infection and efficacy of antibiotic prophylaxis: a cohort study of appendectomy patients in Thailand

Table 1 The association between selected risk factors and surgical site infections

Risk factors	N	Infection	Rate*	Relative risk
				Crude	95% CI	Adjusted**	95% CI
Duration of antibiotic prophylaxis
None	167	5	3.0	1.00	Reference	1.00	Reference
1 day	1159	12	1.0	0.34	0.12–0.97	0.30	0.10–0.89
>1 day	813	9	1.1	0.36	0.12–1.09	0.29	0.09–0.92
Duration of operation
≤ 1.0 hour	1738	16	0.9	1.00	Reference	1.00	Reference
>1.0 hour	401	10	2.5	2.75	1.24–6.11	3.29	1.44–7.52
Age
1–20 years	808	6	0.7	1.00	Reference	1.00	Reference
21–40 years	853	14	1.6	2.23	0.85–5.83	2.15	0.82–5.68
41–60 years	382	5	1.3	1.77	0.54–5.85	1.91	0.57–6.48
>60 years	96	1	1.0	1.41	0.17–11.81	2.11	0.22–20.76
Type of operation
Elective	591	9	1.5	1.00	Reference	1.00	Reference
Emergency	1548	17	1.1	0.72	0.32–1.62	0.78	0.33–1.83
Total	2139	26	1.2	-	-	-	-

* Rate = # infections/100 operations
**Adjusted for sex, age, length of preoperative stay, type of operation, ASA score, and duration of operation

ISSN: 1471-2334