This retrospective study found that the current American College of Rheumatology (ACR) criteria should not be used to diagnose giant cell arteritis (GCA) and all patients suspected of having GCA should undergo a temporal artery biopsy.
The ACR classification criteria specify that the diagnosis of GCA may be made when patients meet three of the following criteria: age over 50 years, new onset of localized headache, temporal artery tenderness or decreased temporal artery pulse, erythrocyte sedimentation rate greater than or equal to 50 mm/hr, or a positive temporal artery biopsy.
In this study, researchers evaluated whether the ACR classification criteria can accurately diagnose GCA without a temporal artery biopsy. They also evaluated the agreement of?? ACR criteria versus temporal artery biopsy alone in diagnosing GCA.
They reviewed the charts of all patients who underwent temporal artery biopsy at the Neuro-ophthalmology Service of the Wills Eye Institute in (where is it located?) between October 2001 and May 2006.
Of 112 patients identified, 35 had positive biopsies. Of those, nine (25.7 percent) would not have been diagnosed with GCA using ACR criteria alone. An additional 16 patients (45.7 percent) met only two criteria and required the positive biopsy to establish the ACR diagnosis of GCA. Eleven of 39 patients (28.2 percent) with negative biopsies met the criteria and would have been diagnosed with GCA.
The ACR criteria with biopsy was 28.6 percent sensitive and 71.8 percent specific for the diagnosis of GCA (positive predictive value - 47.6%, negative predictive value - 52.8%). Adding temporal artery biopsy results increased the sensitivity to 74.3 percent and the specificity to 71.8 percent (PPV – 70.3%, NPV - 75.7%). Diagnostic agreement between the ACR criteria without biopsy results and biopsy results alone was 51.4 percent; adding biopsy results to the criteria increased this to 73 percent.
Based on these results, the authors make the following recommendations:
• The current ACR criteria should not be used to determine the presence or absence of GCA.
• All patients suspected of GCA should undergo temporal artery biopsy of at least 2 cm in length.
• All patients with a positive temporal artery biopsy must be treated with systemic corticosteroids, even in the absence of other ACR criteria.
• Education of physicians who treat GCA should be undertaken to stress the importance of temporal artery biopsy in establishing the diagnosis of GCA.
• The results of temporal artery biopsy, and not ACR criteria, should be used as the only indicator of the presence or absence of disease in research regarding GCA.