Background/Purpose: Multiple epidemiological studies ascertained that GCA is one of the most common systemic vasculitis in western countries. But, there is only one study based on 2 patients in Tennessee to assess the low incidence of GCA in African descent (AD) populations. Moreover, very few series are devoted to these patients in the literature. Our objective was to describe the characteristics of GCA and study the incidence in the Afro-Caribbean (AC) population of Martinique, a French region of the West Indies where inhabitants are more than 90% of AD and have free access to health care including a regional competence center for systemic vasculitis.

Methods: Population based retrospective study in Martinique. Computed files of the 2 pathology units of the island (public and private) were analyzed to find all patients with a positive temporal arteritis biopsy. All medical files were reviewed to assess the incidence, but only AC patients (self-declared) were included to describe the disease in an African descent cohort.

Results: 40 patients had a biopsy proven GCA between 1991 and 2016. Mean age at GCA diagnosis was 75.7 years (SD±7.4; range: 63-91). Main manifestations at diagnosis of the 38 patients of AC origin (30 women, 8 men) were: fever 9.1% (3/33), asthenia 64.5% (20/31), weight loss 75.7% (25/33), headache 69.4% (25/36), jaw claudication 36.3% (12/33), scalp tenderness 35.2% (12/34), anterior ischemic optic neuropathy 31.4% (11/35), stroke 2.9% (1/34), and polymyalgia rheumatica 35.2% (12/34). C-reactive protein was over normal value for 96.8% (n=31; mean value 106.5, range: 7-283). ESR was positive in 86.3% (19/22). Available for 15 patients, CT scan of the aorta and its branches revealed one aortitis and one arteriopathy of lower limbs. All patients were treated by steroids. Twenty three patients (60.5%) were followed >18 months and mean follow up duration was 43.7 months. Eleven patients relapsed. Six patients died (15.8%). Kaplan Meier analysis found 93.9%, 84.6%, 75% survival rates at respectively 6, 12 and 24 months. Crude mean annual incidence of GCA in Martinique was 3.12 cases for 10⁶ inhabitants from 1991 to 2016. Mean number of GCA gradually increased from 0.5 patient/year between 1991 and 2000, 1.6 between 2001 and 2010 to 3.8 between 2011 and 2016, parallel to the increasing proportion of elderly in the martinican population (13% was over 60 years old in 1990, 23% in 2016 and official estimation is 39.6% in 2032).

Conclusion: This is the first population based description of GCA in an AD population. The features in Martinique are similar to the literature, except for the ischemic complications that seem less frequent in our population. Our data confirm the low frequency of GCA in AD populations compared to Caucasians. The retrospective nature of the study and the absence of negative biopsy GCA could weaken conclusion. We note a progressive increase of annual number of cases during the 25 years of survey, parallel to the accelerated ageing of the martinican population. We could hypothesize that low incidence of GCA in AD populations is at least partially related to the low rate of elderly in most of these populations around the world, and could also increase in the future.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/biopsy-proven-giant-cell-arteritis-in-african-descent-populations-incidence-and-characteristics-in-martinique-french-west-indies/