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.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/whole-country-and-regional-incidences-of-giant-cell-arteritis-in-french-continental-and-overseas-territories-a-nationwide-database-analysis/