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FRI0447 The Incidence Rate of GIANT Cell Arteritis in Southern Norway is Lower than Previous Reported: A Result of Temporal Variations or A Sign of A True Shift in Incidence Rates?
  1. A. Diamantopoulos,
  2. G. Myklebust,
  3. E. Wigaard,
  4. L. Amundsen,
  5. D.M. Soldal,
  6. G. Haugeberg
  1. Rheumatology, Hospital of Southern Norway Trust, Kristiansand S, Norway

Abstract

Background Giant cell arteritis (GCA) is the most common form of systemic vasculitis. The highest incidence rates of GCA worldwide have been reported from Southern Norway [32.8/100 000 aged>50 years (biopsy proven GCA 29/100 000 aged>50 years)]1,2. However, these data are from the end of 80's to the early 90's and no reports exist from the recent years. A latest report from Sweden indicates that the incidence rate of biopsy-proven GCA may have decreased over time3.

Objectives The aim of the present study was to examine the incidence rate of GCA in Southern Norway during the past 7 years.

Methods The patients were identified in the hospital electronic medical records by using the ICD-10 codes for GCA (M31.5- 6) and by searching in the electronic biopsy archives of the Department of Pathology during the years 2006-2012. Identified patients with a verified GCA diagnosis after reviewing the medical and the biopsy records were included. Incidence rates were calculated by using the mean population of Southern Norway aged ≥50 years during the period 2006 to 2012.

Results One-hundred and thirty-five GCA patients (mean age 73.6 years, 95% CI 72.0-75.1) were identified during the study period. Among them, 40 were males (30%) (mean age 72.6, 95% CI 69.3-75.9) and 95 females (70%) (mean age 74.0, 95% CI 72.3-75.7). The incidence rates for GCA was 21 per 100 000 aged>50 years (males 13.1 and females 27.9). Ninety-six patients (72.7%) had a positive biopsy of the temporal artery, 30 patients (22.2%) a negative and in 8 patients (6.6%) biopsy was not performed. All the patients with a negative or not performed biopsy satisfied the ACR classification criteria for GCA. Among patients with biopsy proven GCA the incident rate was 14.8 per 100 000 aged>50 years.

Conclusions The incidence rate of GCA in Southern Norway during the years 2006-2012 is approx. 30% lower than reported in previous studies. Particularly for patients with biopsy-proven GCA, the incidence rate was reduced 50% than earlier reported from the same region. Temporal variations could be an explanation for the lower incidence rates reported in this study. However, the lower rates could also be a sign of a true shift in GCA incidence rates in Scandinavia.

References

  1. Haugeberg G, Paulsen PQ, Bie RB. Temporal arteritis in Vest Agder County in southern Norway: incidence and clinical findings. J Rheumatol 2000;27:2624-7.

  2. Gran JT, Myklebust G. The incidence of polymyalgia rheumatica and temporal arteritis in the county of Aust Agder, south Norway: a prospective study 1987-94. J Rheumatol 1997;24:1739-43.

  3. Mohammad AJ, Nilsson JA, Jacobsson LT, Merkel PA, Turesson C. Incidence and mortality rates of biopsy-proven giant cell arteritis in southern Sweden. Ann Rheum Dis 2014.

Disclosure of Interest None declared

DOI 10.1136/annrheumdis-2014-eular.3850

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