Moudrous et al reported a model for the diagnosis of giant cell arteritis (GCA). This can help to identify a patient who may not require a temporal artery biopsy (TAB). The authors are from multiple institutions in The Netherlands.
Patient selection: age > 50 years, new onset headache or visual loss
Predictors of a positive temporal artery biopsy:
(1) weight loss (OR 52.9)
(2) positive halo sign (OR 7.0) on color duplex sonography
(3) thrombocytosis (OR 33.9)
(4) bilateral headache (OR 19.7)
total score =
= SUM(number of predictors present)
Number of Predictors
Positive TA Biopsy
Need for TA Biopsy
0
< 35%
yes
1
< 35%
yes
2
from 58-95%
yes
3
98-100%
no
4
98-100%
no
For combinations of 2 predictors
Predictor 1
Predictor 2
Positive TA Biopsy
weight loss
thrombocytosis
95%
weight loss
bilateral headache
91%
weight loss
halo
79%
thrombocytosis
bilateral headache
87%
halo
thrombocytosis
70%
halo
bilateral headache
58%
Additional factors to consider:
(1) elevated ESR
(2) elevated serum CRP
Performance:
• The area under the ROC curve is 0.93.
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