Patient selection: coronary artery bypass graft surgery
Outcome: post-operative pneumonia
Parameters:
(1) age in years
(2) race
(3) hematocrit in percent
(4) WBC count in 10^3/mL
(5) dyslipidemia
(6) peripheral vascular disease
(7) cerebrovascular disease
(8) diabetes mellitus
(9) liver disease
(10) home oxygen therapy
(11) history of pneumonia
(12) current cigarette smoking
(13) chronic lung disease
(14) history of cardiac arrhythmia
(15) left ventricular ejection fraction in percent
(16) acuity of operation
(17) pre-operative intra-aortic balloon pump
|
Parameter
|
Finding
|
Points
|
|
age
|
|
0.0008 * ((age)^2)) - (0.0813 * (age)
|
|
race
|
white
|
0
|
|
|
non-white
|
0.5046
|
|
hematocrit
|
|
-0.0208 * (hematocrit)
|
|
WBC count
|
|
0.0271 * (WBC count)
|
|
dyslipidemia
|
no
|
0
|
|
|
yes
|
-0.3174
|
|
peripheral vascular disease
|
no
|
0
|
|
|
yes
|
0.3903
|
|
cerebrovascular disease
|
no
|
0
|
|
|
yes
|
0.3668
|
|
diabetes mellitus
|
no
|
0
|
|
|
yes
|
0.2269
|
|
liver disease
|
no
|
0
|
|
|
yes
|
0.5983
|
|
home oxygen therapy
|
no
|
0
|
|
|
yes
|
0.5520
|
|
history of pneumonia
|
no
|
0
|
|
|
yes
|
0.4355
|
|
current smoking
|
no
|
0
|
|
|
yes
|
0.7204
|
|
chronic lung disease
|
no
|
0
|
|
|
mild
|
0.2364
|
|
|
moderate to severe
|
0.6459
|
|
history of arrhythmia
|
no
|
0
|
|
|
remote
|
-0.2672
|
|
|
recent
|
0.3948
|
|
left ventricular ejection fraction
|
|
-0.0111 * (LVEF)
|
|
acuity of operation
|
emergency
|
0.7836
|
|
|
not emergency
|
0
|
|
pre-operative IABP
|
no
|
0
|
|
|
yes
|
0.4614
|
where:
• The handling of the history of arrhythmia is ambiguous. In the equation it appears that the 2 history types are separate, but in Table 2 only 1 option is selected.
X =
= SUM(points for all 18 parameters) - 0.9548
probability of pneumonia =
= 1/(1+EXP((-1)*X))
Performance:
• The area under the ROC curve is 0.74.
