. Author manuscript; available in PMC: 2015 Mar 26.

Published in final edited form as: J Nucl Cardiol. 2014 Mar 29;21(3):453–466. doi: 10.1007/s12350-014-9865-9

Table 5.

The proportion of excess risk^* explained by clinical, symptomatic, and other anatomic CAD factors when estimating the predictive ability of CAC among 2,820 patients with a luminal stenosis

A. Models estimating all-cause mortality
Clinical risk adjustment^**
	Unadjusted HR	Age-adjusted HR	+Risk factor-adjusted HR	+Symptom-adjusted HR
CAC (per category)^*	2.61	2.07	1.98	1.86
P value	<.0001	<.0001	<.0001	<.0001
Proportion of excess risk	–	33.7%	38.9%	46.5%

Anatomic risk adjustment^***
Incremental models	Unadjusted HR	+Luminal stenosis extent-adjusted HR	+LM luminal stenosis-adjusted HR	+Proximal luminal stenosis extent-adjusted HR

CAC (per category)^*	2.61	2.43	2.40	2.19
P value	<.0001	<.0001	<.0001	<.0001
Proportion of Excess Risk	–	11.3%	12.8%	25.8%

B. Models estimating death or MI
Clinical risk adjustment^**
	Unadjusted HR	Age-adjusted HR	+Risk factor-adjusted HR	+Symptom-adjusted HR
CAC (per category)^*	2.36	1.89	1.82	1.71
P value	<.0001	<.0001	<.0001	<.0001
Proportion of excess risk	–	34.7%	39.8%	47.8%

Anatomic risk adjustment^***
Incremental models	Unadjusted HR	+Luminal stenosis extent-adjusted HR	+LM luminal stenosis-adjusted HR	+Proximal luminal stenosis extent-adjusted HR

CAC (per category)^*	2.362	2.23	2.23	2.06
P value	<.0001	<.0001	<.0001	<.0001
Proportion of excess risk	–	9.4%	9.8%	22.1%

The first set of models estimate all-cause mortality and the second set—death or MI.

The proportion of excess risk explained was calculated using the equation: [HR_U − HR_A]/[HR_U − 1] where HR is the hazard ratio and HR_U is an unadjusted HR and HR_A is a risk-adjusted HR.^22,23 For this calculation, HR were continued until the third decimal place.

^**

For the clinical risk adjustment, risk factors included age, hypertension, and diabetes mellitus.

^***

For the anatomic risk adjustment, luminal stenosis extent was defined as the number of vessels with luminal stenosis, LM luminal stenosis was defined as left main luminal stenosis, and proximal luminal stenosis extent was defined as the number of vessels with proximal luminal stenosis.