Background: Temporal arteritis (TA) is the commonest form of primary vasculitis. Symptoms are variable, and therefore the diagnosis (or exclusion) of TA is often difficult. Surgeons are frequently asked to perform a temporal artery biopsy (TAB), but whether the histological result actually influences clinical management is unclear.
Aim: To assess whether, in routine clinical practice, a TAB affects clinical decision-making in patients with suspected TA.
Design: Retrospective audit.
Methods: All patients who underwent a TAB in a single hospital over a 2-year period were identified. This included patients referred from different specialist departments. Individual patient records were examined to document the TAB result, and in particular, the timings of commencement and discontinuation of corticosteroid therapy.
Results: A total of 44 patients were included. TAB was positive in seven patients and negative in 37. In 31, there was no change in their clinical management despite a negative biopsy result: 18 continued with corticosteroids for >6 months with a clinical diagnosis of TA, and in 13 patients a decision to stop steroids, or an alternative diagnosis, was made before the biopsy result was known.
Discussion: In this retrospective study, only a small number of TABs provided positive histological confirmation of TA, and in most patients undergoing TAB, there was little evidence that clinical decision-making with respect to corticosteroid therapy was influenced by the TAB result.
Temporal arteritis (TA), also known as giant-cell arteritis, is the most common primary vasculitis, and involves large-to-medium-sized vessels, especially the cranial branches of arteries arising from the aortic arch. TA is particularly common among individuals (mainly women) over 50 years of age, in whom the prevalence is reported to be 200 cases per 100 000 population.1,2 The presenting symptoms of TA vary widely, which makes clinical diagnosis (and exclusion) of TA difficult. Catastrophic visual loss tends to occur early in the course of the disease, and although seldom reversible, is largely preventable with high-dose corticosteroid therapy.3,4
Temporal artery biopsy (TAB) is the ‘gold standard’ test for making a diagnosis of TA.5,6 A positive biopsy is diagnostic (100% specificity),7 and the histopathological changes often correlate with clinical features of severity,8 but the sensitivity of TAB is relatively low, at 15–40%.9–12 The likelihood of a false-negative TAB may be influenced to some extent by the length of the specimen,13, the presence of skip lesions,14 pathological sectioning techniques and the duration of steroid therapy before biopsy.7,15 Thus, a normal TAB does not exclude the disease, and many patients are diagnosed with TA despite a normal TAB.
Arranging an urgent TAB is often not straight-forward. Requests to vascular surgeons typically originate from physicians, rheumatologists, ophthalmologists and maxillo-facial surgeons, and any surgical procedure is not without risk, discomfort and inconvenience to the patient. The purpose of this study was to review a consecutive series of patients undergoing TAB in a single hospital over a 2-year period, and to evaluate the extent to which the TAB result influenced the clinical management.
Details of all patients undergoing TAB during a 2-year period (2001–3) were obtained from the histology department of the Derby Hospitals NHS Foundation trust. Forty-four patients were identified. These patients all had suspected TA, and were referred to the vascular surgery unit by a range of consultant-led teams in the same hospital, e.g. rheumatology, care of the elderly, general medicine and ophthalmology. In all cases TAB was performed within 5 days of referral. A detailed retrospective analysis of individual patient notes documented clinical and demographic information, and the histology result, and reviewed the clinical decision-making process before and after TAB. In particular, the timing and dose of steroid therapy was carefully recorded in relation to symptoms, TAB and the histology result.
The results are summarized in Figure 1. A total of 44 consecutive patients had TAB performed over a 2-year period, and were included in this analysis. Mean age was 74 years (range 46–91 years). There were seven positive TABs and 37 negative TABs.
Clinical management of biopsy-positive patients
Six of the seven biopsy-positive patients were commenced on corticosteroid therapy prior to the biopsy, and in one patient, steroids were started post-operatively but before the histology result was available. All seven were treated with corticosteroids for a minimum of 6 months.
Clinical management of biopsy-negative patients
Of the 37 patients with negative biopsy results, 26 were commenced on corticosteroid therapy prior to the TAB. Five of these discontinued steroid therapy before the biopsy result was available, and another five had steroid treatment stopped in the light of the biopsy result. Sixteen patients continued corticosteroid therapy for a minimum of 6 months, with a clinical diagnosis of TA.
Eleven biopsy-negative patients were not taking corticosteroids at the time of the TAB. Three of these patients were started on steroids immediately after the TAB: two continued long-term corticosteroid therapy for a clinical diagnosis of TA or polymyalgia rheumatica, and one discontinued steroids when the negative biopsy result was known. Eight patients were never treated with corticosteroids, and were given other diagnoses and management plans prior to the TAB result being known.
This study highlights a number of important issues. Firstly, only seven patients undergoing TAB had a positive histological result to confirm the diagnosis of TA. This low rate of detection is similar to that reported in other series;16 even with bilateral TAB, there is very little (1–5%) extra diagnostic yield.17 A clinical diagnosis of TA does not require a positive biopsy. According to the American College of Rheumatology (ARC) the presence of any three out of the following five criteria yields 91–95% sensitivity and specificity for TA:18 (i) age >50 years; (ii) new-onset localized headache; (iii) tenderness or decreased pulse of the temporal artery; (iv) Westergren erythrocyte sedimentation rate (ESR) >50 mm/h; (v) TAB consistent with arteritis. Thus, a negative TAB is still consistent with a clinical diagnosis of TA. Histological confirmation of TA may have some prognostic implications,6,19 but in general, the low pick-up rate by TAB reinforces the overwhelming importance of the patient history in deciding upon the diagnosis and clinical management.
Several studies have highlighted variability in practice and physician uncertainty concerning the indications for TAB, and proposed new algorithms for clinical decision-making.20,21 The sensitivity of TAB is dependent upon the patient population in which it is applied. In this study, unlike other series, we included all patients referred to a surgeon for TAB. These patients were referred from several different sources within the hospital, not just from expert rheumatologists, which may have a bearing on the relatively low pick-up rate and variability in practice.
Although it is desirable to perform TAB before any treatment is commenced, in practice there is often a delay of several days in arranging surgery, and the consensus is to start high-dose corticosteroids immediately if TA is suspected.7 Resolution of the inflammatory infiltrate takes several weeks or months, so TAB can be undertaken up to 2 weeks after starting steroid therapy without compromising the likelihood of securing positive histological confirmation.22
This was a retrospective study of all patients undergoing TAB in a single hospital serving a catchment population of 600 000. The analysis requires cautious interpretation, but our report was undertaken from a surgical perspective, and was designed to collect information on all patients with suspected TA who were referred for TAB. The results indicate that in over two-thirds of patients the TAB result appeared to have little, if any, effect on clinical decision-making. Eighteen patients continued on corticosteroid therapy despite negative biopsies, and a further 13 either had their steroids stopped after surgery or were given alternative diagnoses before the biopsy result was known. It was not possible to identify any major clinical differences between these two groups, but in this study, a much higher proportion of biopsy-negative patients continued with steroid therapy than in previous large series.23 Only six patients with negative biopsies had their corticosteroids discontinued in the light of the TAB result.
In obtaining patient consent for TAB, and when physicians refer patients to surgeons to perform the procedure, it is often suggested that a positive TAB result will lead to long-term steroid therapy, whereas a negative TAB result will trigger discontinuation of steroids. This study emphasizes that clinical decision-making is more complex, and that decisions about steroid therapy are more influenced by factors such as the consistency and nature of the history, physical signs, and the clinical response to a short-term trial of corticosteroid therapy. In only a few cases was there clear evidence that a negative TAB result had influenced patient management.
Although TAB is a straight-forward procedure, it is not without risk. Well-recognized complications include bleeding, haematoma formation, damage to branches of the facial nerve, failure to identify the artery (especially if non-pulsatile), and scalp necrosis. Unnecessary procedures should be avoided, and the purpose of a TAB needs to be carefully explained to patients. In addition, non-invasive imaging modalities such as ultrasound, MRI and PET scanning are being evaluated with some success in patients with suspected TA.24–27
In conclusion, from this retrospective study which included all patients referred to surgery in a single centre, only a small number of TABs were positive. For the majority of patients, there appeared to be very little evidence that the TAB result had prompted any real change in their clinical management. The patient history, however imprecise, is still by far the most influential factor in clinical decision-making. With cautious interpretation, these results suggest that many patients may be referred inappropriately for TAB, and that the role of this procedure in the assessment and management of patients with suspected TA merits further discussion and clearer guidelines.