Background/Purpose:  Previous retrospective studies have suggested that simultaneous bilateral temporal artery biopsy (TAB) may lead to increased detection rates of giant cell arteritis (GCA). The term discordance represents one unilateral positive biopsy combined with one contralateral negative biopsy. Cases of discordance, through identification of false negatives, support the rationale for obtaining bilateral TAB. Reported discordance rates vary, ranging from 3 to 15 percent. Given the serious outcomes of untreated disease, including permanent blindness, establishing a consensus approach that increases detection of GCA is necessary. We aimed to identify cases of discordant temporal artery biopsies and to examine the role of performing simultaneous bilateral TAB in increasing the diagnostic yield of GCA.

Methods: Procedure codes for TAB were used to identify patients who underwent simultaneous bilateral temporal artery biopsies at three hospitals between the years 2009 and 2013. The following data was collected: biopsy results and length, age, gender, ESR and CRP levels. Patient data and biopsy results were compared based on their respective group: bilateral positive biopsies, bilateral negative biopsies and discordant biopsies. A combined positive biopsy group (bilateral positive biopsies and discordant biopsies) was additionally compared to the bilateral negative biopsy group. A separate chart review was performed for discordant biopsies to identify cases in which bilateral TAB may have increased the diagnostic yield of GCA.

Results: 181 patients were identified that had undergone simultaneous bilateral TAB. The mean age of the positive bilateral biopsy group was 78.2 years compared to 70.3 years for the negative bilateral biopsy group (p < 0.001). The mean age of the combined positive biopsy group was 77.1 years compared to 70.3 years for the biopsy negative group (p<0.001). 38/181 (21%) of patients had biopsy proven GCA. The overall discordance rate was 3.8% (7/181), comprising 18.4% (7/38) of the biopsy positive group. Biopsy lengths did not differ between groups. Average CRP values for the combined positive biopsy group were 6.4 mg/dL when compared to the biopsy negative group of 5.5 mg/dL (p=0.04). When considering localizing symptoms of the discordant group, bilateral TAB would have increased the yield of diagnosis definitively in one case (1/181 (0.5%) or 1/38 (2.6%) combined positive biopsy category alone). This may have increased to 3.3% (6/181) overall or 15.8% (6/38) as part of the combined positive group when considering best possible outcomes.

Conclusion: Bilateral TAB in patients with suspected giant cell arteritis may increase the diagnostic yield in a small number of overall cases. This increase may be more significant when considering the low prevalence of GCA diagnosis. Our results are consistent with previously reported discordance rates. The potential increase in diagnostic yield by performing bilateral TAB may have clinical significance given the negative implications of untreated disease and the side effects of long-term glucocorticoid therapy. Increasing age and CRP values may be associated with an increased likelihood of temporal arteritis.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/discordance-rates-of-bilateral-temporal-artery-biopsies-a-retrospective-analysis/