Validation of a Diagnostic Algorithm of Giant Cell Arteritis

Study Overview
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Brief Summary
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Giant cell arteritis (GCA or temporal arteritis or cranial arteritis) or Horton disease is a vasculitis that occurs in older adults, affecting vessels of medium and large caliber. The diagnosis of GCA is a challenge for general practitioners and specialists. Since 1970, it is based on a combination of clinical, biological and histological signs. Temporal artery biopsy (TAB) was the reference method until recently. However, TAB has many drawbacks. Therefore, researches of the past 20 years have been intended to develop alternative diagnostic methods. This was notably the case of the color Doppler ultrasound (CDU) since the description by Wolfgang Schmidt of the halo sign. Although European and British recommendations put CDU as second line method, many authors suggest the possibility to do without TAB in many cases. In addition, many practitioners believe that it is not ethical to use an invasive unprofitable procedure like TAB, and have already been using CDU in their routine practice. However, no diagnostic algorithm validating this approach in a prospective series has been published to date. Therefore, the present study aim at validating a diagnostic algorithm of giant cell arteritis using color Doppler imaging of temporal arteries and cervicocephalic axes as first screening method.

Official Title
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Validation d'un Algorithme Diagnostique de l'artérite Temporale Giganto-cellulaire basé Sur l'échographie-doppler Couleur Des artères Temporales Superficielles et Des Axes Cervico-encéphaliques

Conditions
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Giant Cell Arteritis

Intervention / Treatment
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* Other: color Doppler ultrasound and TAB in case of CDU negative


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: ≥ 50 years C reactive protein (CRP) above normal Suspected of GCA according to clinician expertise and / or aortitis arteritis or of one or more arteries from the aorta imaging (CT angiography, magnetic resonance angiography or positron emission tomography TDM18FDG) Benefiting from Social Security or receiving it via a third party have given their participation agreement by understanding and accepting the constraints of the study Exclusion Criteria: Received corticosteroid dose ≥ 20 mg of prednisone equivalent for more than 7 days in the month before inclusion Underwent temporal artery biopsy before color Doppler ultrasound History of GCA Terminal palliative phase or suffering from a disease or comorbidities such as life is involved in less than a year Patient with severe cognitive impairment Patient that can not be followed by the investigator for the duration of the study Refusal to participate in the study With enhanced protection (namely those deprived of liberty by a court or administrative order, patient staying in a health or social institution, under legal protection, and patients in emergencies) Pregnant or breastfeeding women, women of childbearing age who do not have effective contraception Participating in another clinical trial.

Ages Eligible for Study
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Minimum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: GCA suspicion<br>A first screening is performed using color Doppler ultrasound. In case of negative results, patients undergo TAB. | Other: color Doppler ultrasound and TAB in case of CDU negative<br>* Screening with color Doppler ultrasound followed by TAB in case of CDU negative<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of CDU false-positive patients | patients with an alternative diagnosis within 2 years of follow-up among patients considered with GCA on a clinico-biological suspicion + Doppler positive. | after 2 years of follow-up | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| rate of TAB positive among negative or doubtful CDU  | Number of TAB positive patients per patients with negative or doubtful CDU | within 1 month (during diagnostic algorithm) | 
| Number of patients with a persistent Halo at second CDU examination | Describe S3/S4 Halo changes, and study correlation between persistence and poorer clinical response | after 2 years of follow-up | 
| Number of correctly interpreted TAB | Reproducibility of TAB interpretation | 1 month (after second blind reading of histological specimen and doppler imaging) | 
| Number of correctly interpreted CDU | Reproducibility of CDU interpretation | 1 month (after second blind reading of histological specimen and doppler imaging) | 
| Cost-result of the algorithm | Diagnostic costs, induced costs, avoided costs | after 2 years of follow-up |