Modified Cardiac Risk Index of Detsky et al

Description

A modified cardiac risk index can be used to perform cardiac risk assessment prior to noncardiac surgery and to estimate a likelihood ratio for the patient. If the overall cardiac complication rate for the a noncardiac surgery (pretest probabilities) is known at an institution, then the likelihood ratio can be used to calculate the cardiac risk for the patient (post-test probability).

Finding	Grouping	Points
myocardial infarction within 6 months	coronary artery disease	10
myocardial infarction more than 6 months ago	coronary artery disease	5
Class III Canadian Cardiovascular Society angina	coronary artery disease	10
Class IV Canadian Cardiovascular Society angina	coronary artery disease	20
unstable angina within 6 months	coronary artery disease	10
alveolar pulmonary edema within 1 week	alveolar pulmonary edema	10
alveolar pulmonary edema, ever	alveolar pulmonary edema	5
suspected critical aortic stenosis	valvular disease	20
rhythm other than sinus or sinus plus atrial premature beats on last preoperative ECG	arrhythmias	5
more than 5 premature ventricular contractions at any time prior to surgery	arrhythmias	5
poor general medical status (pO2 < 60 mm Hg, pCO2 > 50 mm Hg, K < 3.0 mEq/L, HCO3 < 20 mEq/L, BUN > 50 mg/dL, creatinine > 3 mg/dL, abnormal SGOT, signs of chronic liver disease, bedridden for non-cardiac causes)		5
age over 70		5
emergency operation		10

The score is the sum from the individual points, up to a maximum score of 50. From the score, a likelihood ratio for the patient can be estimated.

Score vs Likelihood Ratios (from nomogram Figure 3, page 218)

Score	Likelihood Ratio
0	0.0004
5	0.23
10	1.10
20	4.06
30	7.54
40	10.85
50	13.51

A line approximating this data can be given as:

likelihood ratio =

= (-0.000138 * (score ^3)) + (0.0119553 * (score ^2)) + (0.0175033 * (score)) - 0.06541

If the rate of cardiac complications for a given procedure is known (pre-test probability), then Baye's formula can be used to estimate the risk of cardiac complications for the patient (post-test probability), as

post-test probability =

= ((pre-test probability) * (likelihood ratio)) / (((pre-test probability) * (likelihood ratio)) + (1 - (pre-test probability)))

Likelihood Ratios for Modified Index (at Toronto General Hospital)

Points	Class	Major Surgery	Minor Surgery	All Surgery
0 - 15	I	0.42	0.39	0.43
15 - 30	II	3.58	2.75	3.38
> 30	III	14.93	12.20	10.60

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Description

Specialty

ICD-10