Patient selection: COPD, age >= 65 years
Outcome: exacerbation within the next 24 months. An exacerbation was defined as symptomatic deterioration requiring pulsed oral steroid therapy or hospitalization.
Parameters:
(1) previous exacerbations
(2) FEV1 as percent of predicted, per 5% interval
(3) pack years of smoking, as 2 times the log transformation
(4) history of vascular disease (stroke, transient ischemic attack, peripheral arterial disease)
|
Parameter
|
Finding
|
Points
|
|
previous exacerbation
|
0
|
0
|
|
|
1 or more
|
1.62
|
|
history of vascular disease
|
no
|
0
|
|
|
yes
|
0.65
|
where:
• The LOG10 of 0 cannot be calculated, so a substitute number is given.
X =
= (points for previous exacerbations) – (0.05 * (FEV1 as percent) / 5) + (0.15 * 2 * LOG10(pack years)) + (points for history of vascular disease) – 1.33
probability of exacerbation over the next 2 years =
= 1 / (1 + EXP((-1) *X))
Performance:
• The area under the ROC curve was 0.66 in the validation cohort.
