Histopathological findings considered as TAB-positive GCA (mononuclear cells infiltration with or without giant cells or fibrinoid necrosis in the vessel wall) was detected in 48% of cases in our study. Although this rate is low, there are studies reporting TAB positivity below 20% in the literature [11, 19]. A meta-analysis by Rubenstein et al. showed that the rate of TAB positivity in GCA cases ranged between 50% and 95%, and the overall pooled rate was 77.3% [20]. We found that the median fixed TAB specimen length was 1.7 (0.5–4.0) mm, and was longer in the TAB-positive group than in the TAB-negative group, although this was not statistically significant. Mahr et al. reported that a fixed TAB specimen length of at least 0.5 cm may be sufficient for histopathological diagnosis of GCA [11]. In the diagnosis of GCA, it is also thought that the length of the TAB specimens does not have an important impact on positivity [11, 20, 21]. In 80% of our patients, the time for TAB administration was before the treatment or within the first 7 days after the initiation of the treatment. It has also been reported that delaying the TAB for 14 days or longer may not affect the accuracy of the biopsy result [22]. TAB was not performed later than 14 days in any of our patients.
We determined that TAB positivity increases with age and is more common in women. Similar to our observation, there are studies reporting a higher mean age in TAB-positive patients than in TAB-negative patients, and that ≤ 70 years should downgrade the level of suspicion for GCA [23, 24]. On the contrary, there are publications in the literature reporting that age is not associated with TAB positivity [25, 26]. It has been reported that women are 2 or 3 times more likely to have positive TABs than men [26]. We also found that the probability of TAB positivity in women was 2.9 times higher. Headache was present in 96% of our patients and was the most common symptom at presentation. Although headache is reported in the temporal region with a rate of 70–80%, it is important in prompting suspicion rather than its diagnostic value in GCA [24, 27]. A recent meta-analysis suggested that jaw claudication, limb claudication, temporal artery abnormalities, and anterior ischemic optic neuropathy are the features that should raise the level of suspicion for GCA [24]. We found that the presence of jaw claudication and decreased pulse of the TA on examination were more in TAB-positive patients than in TAB-negative patients. Ischemic optic neuropathy was observed in 56% of our patients. Visual manifestations can be found in 9.6–61.1% of patients with GCA [20]. However, we did not find a relationship between TAB positivity and ischemic optic neuropathy. Gonzalez-Gay et al. determined that a history of constitutional syndrome, presence of visual problems, and an abnormal temporal artery on examination may predict TAB abnormality [25]. Selby et al. stated that scalp tenderness is a significant predictor of a positive TAB [26]. We showed that the factors associated with TAB positivity were female gender, the presence of jaw claudication, and decreased pulse of TA by univariate logistic regression analysis.
In recent study, high ESR was detected in 92% of the patients and high CRP in 80%. In addition, 84% of the patients had normocytic normochromic anemia, 36% of the patients had leukocytosis, and 28% of the patients had thrombocytosis. Of these laboratory findings, only the CRP level was higher in TAB positive patients. In addition, ESR was also determined to be associated with TAB positivity in univariate logistic regression analysis. Anemia, leukocytosis, thrombocytosis, high CRP and ESR levels are frequently detected in laboratory examinations of patients with GCA. However, inflammatory markers may be normal in some patients with GCA [9, 14]. A recent systematic review and meta-analysis revealed that presence of a platelet count of > 400 × 103/µL and an ESR > 60 mm/h in laboratory findings are features that should raise the level of suspicion for GCA [24]. Selby et al. found that CRP and platelets were significant predictors of a positive TAB in a veteran population [26]. Kermani et al. stated that CRP is a more sensitive marker than ESR for a positive TAB in patients with GCA, but it would be useful to evaluate both tests together in the evaluation of patients with suspected GCA [8].
In only 33.3% of our patients who underwent TA ultrasonography, an increase in arterial wall thickness consistent with GCA was found. This rate was lower than the rate of TAB positivity. Therefore, it was thought that TA ultrasonography was not an alternative to biopsy in the diagnosis of GCA. It has been emphasized in the literature that the advantage of TA ultrasonography may be that it provides cost and time savings and reduces the number of TABs [28].
Glucocorticoid treatment was applied to all of our patients. Methotrexate was used in 9 (36%) cases and tocilizumab was used in 1 (4%) case due to steroid side effects or insufficient response to steroid treatment. In GCA, the use of MTX is recommended to reduce the relapse rate and to lower the cumulative glucocorticoid doses [15,29,30)]. It has been reported that tocilizumab, an anti-IL-6 receptor, is beneficial in reducing the cumulative glucocorticoid doses and the relapse rate, and in refractory disease in patients with GCA [15]. One of the biggest problems with the treatment of GCA is the morbidity associated with glucocorticoids. If patients remain untreated, they may have a poor prognosis due to blindness, stroke or myocardial infarction (MI). Approximately 1–3% of patients with GCA die from stroke or MI [13, 31]. Mortality rate was 12% in our patients during the follow-up period. Causes of mortality were sepsis, heart failure, and cardiac arrest. Patients with GCA have a high risk of hospitalization due to cardiovascular comorbidities such as atherosclerotic disease, heart failure and cardiac arrhythmia [32]. A study from Sweden suggested that the mortality risk increased significantly within the first 2 years after the diagnosis of GCA, but then returned to normal [33]. Deaths occurred in the first 6 months in two of our patients, and in the fourth year in one.
The limitations of the study are its retrospective nature and a relatively small sample of patients that admitted to a single tertiary referral center, although we have scanned for a period of approximately 15 years. However, this study provides useful information for clinical practice by detecting clinical and laboratory features associated with TAB positivity in patients with GCA. It can be predicted in which patients the probability of positive TAB is increased and GCA diagnosis is more likely to be made. According to the results of our study, older age, female gender, the presence of jaw claudication and decreased pulse of TA, high ESR and CRP values are predictive features for TAB positivity and GCA diagnosis.