Patient selection: acute myocardial infarction treated invasively, age from 10 to 90.
Outcome: contrast-induced acute kidney injury
Parameters:
(1) age in years by decade
(2) hemoglobin in g/L
(3) volume of contrast used in mL
(4) LOG10(BNP), with method and units not given, will use pg/mL
(5) hypotension before the procedure
(6) eGFR in mL per min per 1.73 square meter BSA
points for age =
= (4.3 * (age) / 10) - 4.3
points for hemoglobin =
= (-0.19 * (hemoglobin)) + 36.11
points for eGFR =
= (0.26 * (eGFR))
points for BNP =
= (25 * LOG10(BNP)) - 25
|
Parameter
|
Finding
|
Points
|
|
volume of contrast
|
<= 100 mL
|
0
|
|
|
> 100 mL
|
24.4
|
|
hypotension
|
no
|
0
|
|
|
yes
|
28
|
total score =
= SUM(points for all 6 parameters)
X =
= (0.05592 * (score)) - 7.651
probability of AKI =
= 1 / (1 + EXP((-1) * X))
Alternatively on page 2:
Y =
= (1.355 * (if contrast vol > 100 mL)) + (1.577 * (if hypotension)) + (0.015 * (eGFR)) + (1.393 * LOG10(BNP)) + (0.239 * (age) /10) - (0.014 * (hemoglobin)) - 6.518
where:
• The age was divided by 10 because it gave closer results to the nomogram results.
probability of AKI =
= 1 / (1 + EXP((-1) * Y))
Performance:
• The area under the ROC curve was 0.78 in the derivation group and 0.72 in the validation group.
