Table 3.

Testing rate and net change (differences in differences estimate) in testing rates during pre-operative visits after 2002 AHA/ACC and ASA guidance in the U.S.

	Testing rate per 100 visits		Unadjusted impact			Adjusted impact
Pre-operative tests	Prior to prof. society guidance (1997-2002)	After prof. society guidance (2003-2010)	Net change after 2002 guidance, per 100 visits**	95% CI	P value	Net change after 2002 guidance, per 100 visits**	95% CI	P value
Plain radiography	11.3	9.9	−1.1	−4.2 to 1.9	0.47	−1.0	−4.1 to 2.2	0.55
Hematocrit	9.4	4.1	0.4	−3.5 to 4.3	0.85	1.2	−2.2 to 4.7	0.48
Urinalysis	12.2	8.9	1.9	−2.2 to 6.1	0.36	2.7	−1.7 to 7.1	0.23
ECG	19.4	14.3	−7.3	−12 to −3.1	<0.001	−6.7	−10.6 to −2.7	0.001
Cardiac stress test	1.0	2.0	0.8	−0.1 to 1.7	0.073	0.7	−0.1 to 1.5	0.082
Any test*	28.1	25.8	0.8	−4.7 to 6.3	0.78	1.8	−3.7 to 7.3	0.53
Any test†	30.5	27.0	0.2	−8.4 to 8.8	0.97	1.9	−5.8 to 9.6	0.63

Abbreviations: CI, confidence interval; ECG, electrocardiography; No., number; OR, odds ratio; Prof., professional

^**Net changes incorporate pre-2002 and post-2002 testing rates in both pre-operative visits and general medical exams and reflect differences-in-differences estimates.

^*Does not include hematocrit blood tests, which were available from 1997-2004 only

^†Includes hematocrit; therefore time period limited to 1997-2004