1. Outcomes no antibiotics vs antibiotics.

Outcomes	No antibiotics	Antibiotics	RR (95 % CI)
Complications within 30 days	9/665	10/664	0.89 (0.30 to 2.62)
Emergency surgery within 30 days	3/665	7/664	0.47 (0.13 to 1.71)
Recurrence beyond 30 days	121/502	124/522	1.01 (0.81 to 1.25)
Complications beyond 30 days	23/502	22/522	1.08 (0.61 to 1.93)
Emergency surgery beyond 30 days	19/502	13/522	1.42 (0.58 to 3.49)
Elective colonic resection	26/502	24/522	1.10 (0.41 to 2.97)
Mortality	12/630	16/639	0.98 (0.60 to 1.59)
Adverse events	0/664	6/665	0.14 (0.02 to 1.13)