Table 3.

Unadjusted risk per 1000 Medicare outpatients for adverse events within 30 days of initial CT colonography (CTC) or initial optical colonoscopy (OC) received between January 2007 and December 2008 by indication

	Initial CTC				Initial OC
	Asymptomatic (n=1384)		Symptomatic (n=4,730)		Asymptomatic (n=54,039)		Symptomatic (n=95,163)
	Events (n)	Risk	Events (n)	Risk	Events (n)	Risk	Events (n)	Risk
Gastrointestinal bleeding	4	2.9	72	15.2	371	6.9	2100	22.1
Perforation	1	0.7	3	0.6	46	0.9	135	1.4
Other GI	5	3.6	105	22.2	311	5.8	2381	25
--- Ileus	0	0	11	2.3	76	1.4	497	5.2
--- Nausea, Vomiting or Dehydration	4	2.9	71	15	169	3.1	1552	16.3
--- Abdominal pain	2	1.4	32	6.8	107	2	588	6.2
CVD events	26	18.8	252	53.3	610	11.3	4557	47.9
--- MI or angina a	4	2.9	45	9.5	176	3.3	936	9.8
--- Arrhythmias	14	10.1	134	28.3	329	6.1	2425	25.5
--- CHF	5	3.6	114	24.1	94	1.7	1780	18.7
--- Cardiac or respiratory arrest b	1	0.7	27	5.7	43	0.8	501	5.3
	9	6.5	40	8.5	149	2.8	796	8.4

^aincluding chest pain

^bnot including shortness of breath