Background/Purpose:

Giant cell arteritis (GCA), the most common primary vasculitis, can cause irreversible blindness in 20-30% of untreated cases, but glucocorticoid therapy leads to significant toxicity in > 80% of patients. Ultrasound has proven to be effective in diagnosing GCA and has shown advantages in monitoring disease activity. We reviewed data on all patients referred to a single university hospital between August 2014 and March 2015 who were seen in a “fast-track” service established to diagnose and evaluate suspected GCA or a suspected flare.  All patients underwent rapid evaluation by a combination of ultrasound (of the temporal and axillary arteries) and standard clinical assessment to reduce the risk of misdiagnosis or instituting unnecessary treatment.

Methods:

We performed a retrospective analysis and comparison of the ultrasound findings with the clinical features, temporal artery biopsy (TAB) results and decision to treat patients with suspected or established GCA. The ultrasound scan was considered positive when we identified the presence of a dark halo around the temporal artery wall or a homogeneous hypoechoic wall thickness > 1.5 mm in the axillary arteries.

Results:

We performed 137 scans in 118 patients (67% females, mean [SD] age 71 ± 11 years). In 89 cases, patients were referred for suspected GCA: 60% were already on high-doses of steroids (mean of 12 ± 10 days); 78% had headache; 62% high inflammatory markers; 43% abnormal vascular examination (e.g. diminished/absent pulse or bruits); 34% scalp tenderness; 33% polymyalgia rheumatica; 25% jaw claudication and 25% visual symptoms. In 32 cases the scan was positive: 9 also had a TAB (4 positive) and all were treated as GCA. In 50 cases the scan was negative: 20 also had a TAB (1 positive) and 5 were treated as GCA. In 7 cases the scan was inconclusive requiring further investigations (e.g. TAB). Patients with a positive scan had a mean CRP of 51.8 ± 50.8 g/dl and a mean ESR of 42.4 ± 40.1 mm/hour; patients with a negative scan had a mean CRP of 14.9 ± 21.9 g/dl and a mean ESR of 26.8 ± 23.5 mm/hour (p=0.003 and p=0.245, respectively). We scanned 48 patients with an established diagnosis of GCA to assess for flare or monitor disease activity: 25 had a positive scan (18 increased medication; 7 were follow-ups with improvement from baseline) and 23 had a negative scan (allowing a safer taper or withdrawal of glucocorticoids). Patients with a positive scan had a mean CRP of 10.7 ± 10.3 g/dl and a mean ESR of 21.4 ± 18.0 mm/hour; patients with a negative scan had a mean CRP of 3.9 ± 4.3 g/dl and a mean ESR of 24.1 ± 17.4 mm/hour (p=0.025 and p=0.663, respectively).

Conclusion:

The combination of rapid clinical evaluation and ultrasound were key elements in diagnosis and monitoring of GCA, allowing more flexible use of glucocorticoid dose regimens and reducing the number of TABs required. The only patient with a negative scan but a positive TAB had already received 20 days of glucocorticoids, suggesting that delay in investigation after starting therapy could affect the results of the scan.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/how-can-we-use-ultrasound-in-the-diagnosis-and-management-of-patients-with-giant-cell-arteritis/