0475: Whole-country and Regional Incidences of Giant Cell Arteritis in French Continental and Overseas Territories: A Nationwide Database Analysis

Hubert De Boysson¹, Lydia GUITTET², Damiano CERASUOLO², Rémy MORELLO², Samuel DESHAYES² and Achille Aouba¹, ¹Department of Internal Medicine, UR4650 PSIR, Normandie Univ, UNICAEN, CHU de Caen Normandie, Caen, France, ²Caen University Hospital, Caen, France

Background/Purpose: The incidence rate of giant cell arteritis (GCA) is poorly studied in France. Therefore, we conducted a national hospital database study to assess the overall and regional incidence rates of GCA in France, including overseas territories.

Methods: Through the national hospitalization database of all patients hospitalized in France, new incidental GCA was identified using ICD-10 medical codes (M31.5 = GCA; M31.6 = GCA and polymyalgia rheumatica [PMR]) during 2013-2019. The regional incidences were analysed by graphical methods and Poisson regression.

Results: From 2013 to 2019, 16,540 patients were newly diagnosed with GCA+/- PMR through hospital recruitment in French territory, of which 16,436 were detected in continental France and 104 in overseas areas.

A mean of 2363 (range: 2170-2722) new GCA diagnoses were made each year in France. Sixty-five percent of cases were females. The age repartition was as follows: 5.2% of GCA patients were between 50 and 59 years old, 22.1% were between 60 and 69, 37.3% were between 70-79 and 35.5% were over 80.

Incidence rates did not significantly vary each year during the study period; however, the use of a temporal artery biopsy to diagnose GCA significantly decreased, from 61% in 2013 to 38% in 2019 (p< 0.0001).

The crude incidence rates of GCA+/-PMR per 100,000 persons aged ≥50 years were 9.64 [9.50—9.79] in continental France and 2.91 [2.35—3.47] in overseas areas. The crude incidence rate was 11.43 [11.21—11.65]) in females and 7.50 [7.31—7.70] in males (p< 0.0001). The incidence rate of GCA+/- PMR increased with age, from 50-54 to 80-85 years old in women and from 50-54 to 85-89 in men. It decreased in both sexes thereafter.

The detailed standard incident rates (SIRs) of GCA +/- PMR in the recently reformed 13 and 22 old continental French regions are shown in Table 1, Figure 1A and B. In overseas areas, the SIR of GCA+/- PMR was 3.45 [2.77–4.12].

At a departmental level (97 continental departments, Figure 1C), a gradient was noted with increasing SIRs from east to west (β= -0,016 [-0,023 – -0,009], p< 10^-3). No significant north–south gradient was observed.

Conclusion: This French nationwide study provides new and dynamic insights regarding GCA +/- PMR incident rates at the country and regional levels. Important rate differences were observed between continental France and the overseas areas.
Table 1. Standardized incidence rates of GCA in the 13 main (in bold) and 22 historical (in italic) regions in continental France.

Figure 1. Standardized incident rates of GCA +/- PMR in the 13 new main regions (A), in the 22 former regions (B) and in the 97 continental (including Corsica) departments (C). Numbers on the Figure 1B refer to the French historical regions described in Table 1.
Disclosures: H. De Boysson, None; L. GUITTET, None; D. CERASUOLO, None; R. MORELLO, None; S. DESHAYES, None; A. Aouba, Roche.