Equation of Tiret et al for Predicting Risk of Anesthesia Complications in Patients Over 40 Years of Age

Patient selection:

(1) age over 40 years

(2) noncardiac surgery

Parameters used in step-up logistic regression:

(1) age of the patient

(2) ASA classification score

(3) emergency vs elective procedure

(4) major vs minor procedure

Major procedures:

(1) neurosurgery

(2) major intraperitoneal

(3) intrathoracic

(4) aortic

(5) major orthopedic

risk score =

= 1000 * ((0.015 * (age in years)) + (0.7 * (value for emergency surgery)) + (1.079 * (value for major procedure)) + (1.121 * (ASA score)))

where:

• The regression coefficients are the combined subset values from Table II, page 951.

Interpretation:

• minimum score: 1,736 (age 41, ASA class 1, nonemergency, not major procedure)

• maximum score: around 8,880, depending on age

• The risk of complications increases as the risk score increases.

• Complications occurring with scores under 2,000 were most often due to errors in anesthesia or the rare occurrence of anaphylaxis to the anesthetic agent.

from Table IV, page 952

In the implementation I have used < 3,000 as low risk; > 5,000 as high risk; and 3,000-5,000 as intermediate risk groups.