Hu et al reported a nomogram for predicting blood transfusion for a patient undergoing total knee arthroplasty (TKA). The authors are from The Affiliated Hospital of Qingdao University in China.
Patient selection: total knee arthroplasty (TKA)
Parameters:
(1) number of knees replaced
(2) coronary heart disease (CHD)
(3) age from 20 to 100 years
(4) body mass index (BMI) in kg per square meter, from 10 to 70
(5) hemoglobin in g/L, from 40 to 160
points for age =
= (0.3025 * (age)) + 27.85
points for BMI =
= 63.8167 - (0.5817 * (BMI))
points for hemoglobin =
= 137 - (0.862 * (hemoglobin))
|
Parameter
|
Finding
|
Points
|
|
number of knees replaced
|
1
|
47.9
|
|
|
2
|
64.5
|
|
coronary heart disease
|
no
|
47.9
|
|
|
yes
|
52.6
|
total score =
= SUM(points for all of the parameters)
Interpretation:
• minimum score: 160.5
• maximum score: 375.1
value of X =
= (0.1028 * (score)) - 28.66
probability of transfusion =
= 1 / (1 + EXP((-1) * X))
