The Applanation Tonometry in GCA Pilot (ATOM-GCA)

The Applanation Tonometry in Giant Cell Arteritis Pilot

The Applanation Tonometry in Giant Cell Arteritis (ATOM-GCA) study will answer the following questions:

1. How does PWV, measured by applanation tonometry of temporal arteries, differ between patients with and without a final diagnosis of GCA (based on pre-defined criteria 6 months after inclusion)?

2. What is the diagnostic accuracy and positivity cutoff of the PWV, measured by applanation tonometry, in detecting:

   1. A clinical diagnosis of GCA (based on pre-defined criteria 6 months after inclusion)?
   2. Inflammation of temporal arteries on high-resolution ultrasound?
3. What is the acceptability and adherence of repeat applanation tonometry during the follow-up period in patients with GCA?

Study Overview

• Status: Active, not recruiting
• Conditions: Giant Cell Arteritis
• Intervention / Treatment: Diagnostic test: Standardized GCA assessment; Diagnostic test: Repeat applanation tonometry (optional); Diagnostic test: Applanation tonometry

Detailed Description

ATOM-GCA is a single-center, cross-sectional vanguard study.

• Study Type: Observational
• Enrollment (Estimated): 146

Contacts and Locations

Study Locations

• Canada
  • Quebec
    • Montreal, Quebec, Canada, H4J1C5
      • Vasculitis Clinic, Hopital du Sacre-Coeur de Montreal

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 50 years to 95 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Consecutive patients referred for suspected new-onset GCA

Description

Inclusion criteria:

To be included in ATOM-GCA, participants must meet all the following criteria:

1. Age > 50 years.
2. Referral for suspected, new-onset GCA.
3. Ability to understand and willingness to sign an informed consent form.
4. Willingness to comply with study visits and procedures.

Exclusion criteria:

An individual who meets any of these criteria will be excluded from ATOM-GCA:

1. Referral for a suspected GCA relapse.

2. Current use of systemic glucocorticoids, with the following duration at the baseline visit:

   1. ≥ 14 consecutive days of oral glucocorticoids in the previous 30 days, or
   2. ≥ 7 consecutive days of oral glucocorticoids if intravenous glucocorticoids were administered in the previous 30 days.
3. Current use of any conventional or biologic immunosuppressive therapy.
4. Temporal artery biopsy prior to the study visit.

Study Plan

How is the study designed?

Design Details

• Observational Models: Cohort
• Time Perspectives: Prospective

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Non-GCA group; Participants who do not meet the criteria (above) for GCA at month 6.	Diagnostic test: Standardized GCA assessment; Clinical assessment, blood test review, high-resolution temporal artery ultrasound using a 24mHz probe.; Diagnostic test: Applanation tonometry; Applanation tonometry will be used to measure arterial stiffness in these segments, bilaterally: Superficial temporal artery to frontal temporal artery; Common carotid artery to superficial temporal artery
GCA group; Definite confirmation of GCA will occur 6 months after study inclusion, following the phone follow-up, and will require all the following features: 1) initial symptoms and clinical evolution consistent with GCA; 2) at least one positive test for cranial GCA (ultrasound of temporal arteries, temporal artery biopsy, cranial MRI, cranial PET); and 3) satisfies the 2022 ACR-EULAR classification criteria for GCA.	Diagnostic test: Standardized GCA assessment; Clinical assessment, blood test review, high-resolution temporal artery ultrasound using a 24mHz probe.; Diagnostic test: Repeat applanation tonometry (optional); Repeat index test at month 6 and at disease relapse.; Diagnostic test: Applanation tonometry; Applanation tonometry will be used to measure arterial stiffness in these segments, bilaterally: Superficial temporal artery to frontal temporal artery; Common carotid artery to superficial temporal artery

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
PWV in patients with and without GCA	The primary outcome of ATOM-GCA is to compare the mean PWV in patients with GCA to the mean PWV in individuals without GCA. Final confirmation of GCA will be determined 6 months after study inclusion. This analysis will establish whether the PWV differs in GCA. Additionally, we will explore the optimal PWV cutoff and evaluate its diagnostic performance to confirm a final diagnosis of GCA at 6 months.	Baseline

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Diagnostic performance of the PWV	The secondary outcome is to assess the diagnostic performance of the PWV to predict the presence of GCA-induced inflammation on high-resolution ultrasound. This analysis will identify the optimal PWV cutoff to potentially replace temporal artery ultrasound in GCA diagnosis.	Baseline

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportion of participants who accept repeat applanation tonometry	In patients with GCA, we will evaluate the acceptability of applanation tonometry by measuring the proportion of participants who, at the baseline visit, consent to undergo repeated applanation tonometry during the follow-up period.	Baseline
Proportion of participants who complete repeated applanation tonometry	The adherence of repeat applanation tonometry (proportion of patient who successfully complete applanation tonometry at month 6 and at relapse) will be assessed in those who consented to have repeat applanation tonometry.	Up to 2 years

Collaborators and Investigators

• Sponsor: Centre Integre Universitaire de Sante et Services Sociaux du Nord de l'ile de Montreal
• Investigators: Study Chair: Jean-Paul Makhzoum, CISSS du Nord-de-l'ile de Montreal

Publications and helpful links

General Publications

• Zarka F, Rheaume M, Belhocine M, Goulet M, Febrer G, Mansour AM, Troyanov Y, Starnino T, Meunier RS, Chagnon I, Routhier N, Benard V, Ducharme-Benard S, Ross C, Makhzoum JP. Colour Doppler ultrasound and the giant cell arteritis probability score for the diagnosis of giant cell arteritis: a Canadian single-centre experience. Rheumatol Adv Pract. 2021 Nov 10;5(3):rkab083. doi: 10.1093/rap/rkab083. eCollection 2021.
• Baalbaki H, Jalaledin D, Lachance C, Febrer G, Rheaume M, Makhzoum JP. Characterization of visual manifestations and identification of risk factors for permanent vision loss in patients with giant cell arteritis. Clin Rheumatol. 2021 Aug;40(8):3207-3217. doi: 10.1007/s10067-021-05643-5. Epub 2021 Feb 12.

Helpful Links

• Vasculitis Clinic - University of Montreal

Study record dates

Study Major Dates

• Study Start (Actual): July 30, 2025
• Primary Completion (Estimated): June 1, 2026
• Study Completion (Estimated): July 1, 2027

Study Registration Dates

• First Submitted: January 17, 2023
• First Submitted That Met QC Criteria: January 26, 2023
• First Posted (Actual): January 30, 2023

Study Record Updates

• Last Update Posted (Actual): August 7, 2025
• Last Update Submitted That Met QC Criteria: August 2, 2025
• Last Verified: July 1, 2025

More Information

Terms related to this study

• Keywords: diagnosis
• Additional Relevant MeSH Terms: Musculoskeletal Diseases; Cerebrovascular Disorders; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Vascular Diseases; Cardiovascular Diseases; Muscular Diseases; Rheumatic Diseases; Connective Tissue Diseases; Autoimmune Diseases; Immune System Diseases; Autoimmune Diseases of the Nervous System; Skin Diseases; Skin Diseases, Vascular; Vasculitis; Vasculitis, Central Nervous System; Polymyalgia Rheumatica; Giant Cell Arteritis; Arteritis
• Other Study ID Numbers: 2020-1890

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No