To et al reported a model and data for predicting perioperative transfusion in elective hip and knee arthroplasty. One set of data was for patients who received a hip arthroplasty. The authors are from multiple institutions in Australia.
Patient selection: hip arthroplasty
Parameters:
(1) preoperative hemoglobin in g/dL
(2) sex
(3) age in years (less than 65 years; greater than or equal to 65 years)
(4) presence of both female sex and age >= 65 years
Category
Value of X Based on Figure 2
female, age LT 65 years
(-0.682 * (hemoglobin)) + 7.462
female, age GTE 65 years
(-0.6807 * (hemoglobin)) + 8.661
male, age LT 65 years
(-0.7 * (hemoglobin)) + 8.059
male, age GTE 65 years
(-0.6813 * (hemoglobin)) + 7.914
probability of blood transfusion =
= 1 / (1 + EXP((-1) * X))
The general equation is shown on page 318 but the coefficients and intercept are not provided. Based on an analysis of the various models the following guesses at the values are:
Factor
Odds Ratio
Best Guess
a
7
b1
0.51
-0.68
b2
3.56
1.06
b3
-0.145
b4
-0.6
b5
3.37
1.3
Performance:
• The area under the ROC curve is 0.84.
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