Ultrasound Detects GCA Better Than Temporal Artery Biopsy

A comparative study suggests that temporal artery biopsy (TAB) may often be unnecessary to diagnose giant cell arteritis. Cranial duplex ultrasound proved to have greater sensitivity and a comparable specificity for the condition. 

The study by a team at Queen Elizabeth Hospital and the University of Birmingham UK evaluated the diagnostic tests against confirmed clinical diagnoses of GCA at three months. Existing American College of Rheumatology (ACR) criteria including TAB were unable to predict or exclude the diagnosis as well as ultrasound, perhaps leaving patients at risk of either missing steroid treatment that can rescue vision or taking the drugs unnecessarily, said lead author Adam Croft PhD of the university's Centre for Translational Inflammation Research.[[{"type":"media","view_mode":"media_crop","fid":"25127","attributes":{"alt":"","class":"media-image","height":"256","id":"media_crop_3157643539685","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"2251","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","title":"Comparison of Ultrasound and Temporal Artery Biopsy for Suspected GCA","typeof":"foaf:Image","width":"427"}}]]

Among 87 patients who had cranial ultrasound for suspected GCA, 36 (41%) were clinically confirmed to have the condition three months later. Of the 30 who had a positive cranial ultrasound, 29 (96%) were later diagnosed with GCA. Only 21 (58%) of the 36 patients with more than three of the ACR criteria (age ≥ 50; new onset headache; tenderness or reduced pulsation of the temporal artery; elevated blood ESR; and positive TAB) had a GCA diagnosis at three months. 

In the study, reported at this week's 2014 annual meeting of the European Union League Against Rheumatism (EULAR), ultrasound reports were independently classified according to whether there was evidence of an arteritis or not. Explicit ultrasound features of GCA such as a halo sign were not required to determine a diagnosis.

In contrast, the high positive (97%) and negative predictive value (88%) of cranial ultrasound over TAB indicates that the latter may be unnecessary, the team concludes, especially when clinical suspicion of GCA is either high or quite low.