Diagnostic validity of Doppler ultrasound in giant cell arteritis

To assess the validity of Doppler ultrasound in the diagnosis of giant cell arteritis (GCA), using the American College of Rheumatology (ACR) criteria and biopsy and using as gold standard the patient's definitive clinical diagnosis.

An observational, descriptive and analytical study of 451 consecutive patients with suspected GCA was conducted, and the clinical history and ultrasound findings of the patients were reviewed. The validity of ACR criteria, temporal arteritis biopsy (TAB) and Doppler ultrasound in the diagnosis of GCA was calculated using the final diagnosis of the doctor in charge as the gold standard.

The validity and security of the diagnostic tests used were as follows: ACR criteria had 65.37% sensitivity and 62.89% specificity; positive predictive value [PPV] 70%; negative predictive value [NPV] 57.82%, likelihood ratio [LR] + 1.7619 and LR - 0.5506. Doppler ultrasonography had 91.60% sensitivity and 95.83% specificity; PPV 96.62%; NPV 89.76%, LR + 21.81 and LR - 0.0876; TA biopsy 42.86% sensitivity and 100% specificity; PPV 100%; NPV 35.71% and LR - 0.5714.

The halo sign, especially if bilateral, is a strong predictor of GCA with a level of accuracy sufficient to recommend its introduction into clinical practice and, in our opinion, should be considered in future classification criteria sets.