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Research into GCA

This page presents a round-up of current research projects on Giant Cell Arteritis (GCA).

Diagnosis

a) TABUL study on ultrasound in diagnosis.

The Temporal Artery Biopsy –v Ultrasound in diagnosis of GCA (TABUL) study is being led by Prof. Raashid Luqmani at the Nuffield Orthopaedic Centre in Oxford. This NIHR (National Institute of Health Research) portfolio adopted study has been designed to investigate the specificity and sensitivity of temporal artery biopsy compared to ultrasound for the diagnosis of (GCA). The study is funded by the NIHR Health Technology Assessment (HTA, Reference Number HTA Project 08/64/01).

GCA causes inflammation and narrowing of blood vessels, and can cause blindness in one third of patients. It is highly important that a prompt, accurate diagnosis of GCA is made and a steroids treatment is given for two or more years. Temporal Artery Biopsy (TAB) is the current ‘gold-standard’ but an imperfect test for diagnosis of GCA.

The patient will have a biopsy of a temporal artery (a minor procedure performed under local anaesthetic to remove a sample of one of the scalp arteries).  However, around 4 out of 10 patients will have a normal falsely negative result, which will provide an imprecise diagnosis.

As part of the TABUL study, an ultrasound scan of the arteries in the side of the head and under the arms is performed before the patient goes for their TAB. Ultrasound seems to be useful in the identification of GCA and does not involve surgery; the test can be performed as an outpatient. The TABUL study will compare the temporal artery ultrasound to temporal artery biopsy, and aims to discover whether ultrasound is as reliable as biopsy, whether it is as acceptable to patients, and whether it is cost effective.

Patients can only be recruited into this study when they are first suspected of having GCA, and they must not have had steroids recently for any reason apart from PMR. They will receive an initial clinical assessment, blood tests, ultrasound and biopsy within 7 days of starting high dose steroid treatment. The study includes three visits (baseline, after 2 weeks and at 6 months) and otherwise patients are seen in the normal clinic as required.

b) Please see also the section below on the Fast Track Evaluation Study.

c) GCA symptoms with negative biopsy?

A further recent study from the United States has suggested that in people with the visual symptoms of GCA, but a negative temporal artery biopsy, it may actually be varicella-zoster virus (chicken pox virus) that is causing the symptoms (Nagel and colleagues). Whilst this doesn’t mean that people with a negative biopsy definitely do not have GCA, it does present another avenue of investigation for doctors.

Sight loss in GCA

Fast track evaluation study

In 2013 a team led by Prof Dasgupta at Southend University Hospital published the results of an evaluation study of the effectiveness of a ‘fast-track’ diagnostic pathway for cases of suspected GCA.  The pathway, which involved a dedicated phone line for GPs to use, and the guarantee that the patient would be seen by a rheumatologist within 24 hours, had the effect of cutting the number of cases of full or partial sight loss from 17 a year to 1 (a referral from out of the area).  The evaluation project, which involved an economist from the Department of Health) set out to establish the cost-effectiveness of the fast-track pathway and concluded that not only did it save sight, but it also saved money, compared with the traditional pathway of referral.  PMRGCAuk is now collaborating with other organisations to see how this pathway can be ‘rolled out’ to other areas of the country.

PMRGCAuk and Fight for Sight are jointly funding two small-scale projects on the theme of sight loss in GCA.  These will take place in 2014.

BOSU study of incidence of sight loss

Previously there was no systematic capture of data regarding the number of incidents of sight loss in the UK caused by late diagnosis of GCA. The research team, led by Prof. Bhaskar Dasgupta, will collaborate with the British Ophthalmic Surveillance Unit (BOSU) to collect monthly reports of all such cases, so that in future we will be able to tackle the problem on the basis of actual national figures rather than estimates extrapolated from small local studies.

Study into what is happening in the eye

Sight loss in GCA is caused by ‘optic neuropathy’, described as a stroke involving the optic nerve. Dr Eion O’Sullivan and his team will carry out a study to identify changes in and around the optic nerve during the ‘acute’ stage of GCA.

Treatment for GCA

A paper has recently been published regarding the screening of patients with GCA for aortic structural damage (García-Martínez and colleagues). This paper from Spain describes how around a third of people with GCA will develop damage to their aorta over 10 years, but that this still does not warrant screening for this damage in the majority of people. This is because the surgery needed to correct damage to the aorta is very risky and many people with GCA are older and have multiple health conditions. The authors suggest that after further research into the outcomes of surgery and gathering more information on steroid doses, it might be sensible to screen people with GCA who are in good general health and would be fit enough for surgery if it were needed.

In terms of withdrawing steroids in GCA, a French group of researchers has suggested that long-term steroid use might result in adrenal insufficiency, with symptoms including weakness, fatigue, depression and muscle and joint pain (Jamilloux and colleagues). They found this was particularly likely when someone had received a high dose of steroids or taken them for a long time. The authors suggested that patients might be offered a test called an ACTH stimulation test before steroids are withdrawn to see if this adrenal insufficiency is likely to occur. However, this is only one study, and it seems unlikely that this will be in common use in the near future.

References

Nagel MA, Bennett JL, Khmeleva N, Choe A, Rempel A, Boyer PJ, Gilden D.Multifocal VZV vasculopathy with temporal artery infection mimics giant cell arteritis. Neurology. 2013;80(22):2017-21.

García-Martínez A, Arguis P, Prieto-González S, Espígol-Frigolé G, Alba MA, Butjosa M, Tavera-Bahillo I, Hernández-Rodríguez J, Cid MC. Prospective long term follow-up of a cohort of patients with giant cell arteritis screened for aortic structural damage (aneurysm or dilatation). Ann Rheum Dis. 2013 Jul 19. doi: 10.1136/annrheumdis-2013-203322. [Epub ahead of print]

Jamilloux Y, Liozon E, Pugnet G, Nadalon S, Heang Ly K, Dumonteil S, Gondran G, Fauchais AL, Vidal E. Recovery of adrenal function after long-term glucocorticoid therapy for giant cell arteritis: a cohort study. PLoS One. 2013;8(7):e68713.

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