Every year, up to 44% of patients who undergo a scalp artery biopsy for suspected giant cell arteritis (GCA) receive a normal result that cannot rule out the disease. This matters because GCA inflames and narrows blood vessels, causing blindness in one in three patients if untreated. Doctors must start high-dose steroids immediately on suspicion, but the only confirmatory test—a surgical biopsy—often fails. Withdrawing steroids in a patient who actually has GCA risks blindness; continuing them in a patient without GCA invites serious side effects like osteoporosis, diabetes, and infection. The investigators will study 402 patients with suspected GCA, giving each both an ultrasound and a biopsy within a week of starting steroids. After six months, they will reassess each diagnosis to compare the accuracy of ultrasound against biopsy, and determine whether combining both tests improves diagnostic certainty. They will also model how each test—alone or together—would change treatment decisions and costs relative to patient quality of life. If ultrasound proves as accurate as or better than biopsy, it could replace an invasive surgical procedure with a simple outpatient scan, reducing unnecessary steroid use and the harms that come with it.
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Giant Cell Arteritis (GCA) causes inflammation and narrowing of blood vessels and can cause blindness in one third of patients. It is important that a prompt, accurate diagnosis of GCA is made and treatment given as steroids for two or more years. Currently there is no 100% accurate test for GCA. Patients usually have new headache and scalp tenderness, typically with an abnormal blood test. However, it can be difficult to distinguish non-serious forms of headache from GCA; infection produces similar abnormal blood results. If there is a suspicion of GCA, treatment with steroids is started straight away. To confirm a diagnosis, the patient will need a biopsy of a temporal artery (a minor procedure performed under local anaesthetic to remove a sample of one of the scalp arteries). However, up to 44% of patients will have a normal biopsy. Therefore it is difficult to know if a patient with a normal biopsy does or does not have GCA. Withdrawing steroid treatment may increase the risk of blindness. Continuing treatment in a patient without GCA increases the risk of side effects (e.g., weight gain, infection risk, osteoporosis and fracture risk, high blood pressure, diabetes, cataracts). It is important to improve diagnostic tests for GCA. Another test to help in diagnosing GCA is an ultrasound scan of the arteries in the side of the head and under the arms. Ultrasound does not involve surgery; it is a simple test which can be performed as an out patient. Gel is applied to both sides of the head and under each arm. A sound probe is placed over the artery at each site to produce the scan. The investigators' study will examine the role of ultrasound in diagnosis of 402 patients with suspected GCA. All patients will have an ultrasound examination in addition to biopsy within a week of starting steroids. Patients will be treated according to usual practice. After six months, the investigators will reassess the diagnosis. The investigators will look at the accuracy of ultrasound compared with or combined with biopsy. The investigators will look at how a doctor's knowledge of ultrasound results or biopsy results alone would affect the diagnosis and recommendation to continue or stop steroid treatment. The investigators will assess whether knowledge of both results together would alter the diagnosis and treatment. The investigators will collect information to estimate the costs of different ways of diagnosing GCA in relation to the impact on quality of life.
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