166. PREVALENCE OF BIOPSY-PROVEN GIANT CELL ARTERITIS IN SOUTHERN SWEDEN

Abstract

Background: Few previous studies have examined the prevalence of giant cell arteritis (GCA). The main objective of this study is to investigate the prevalence of temporal artery positive GCA (TAB+GCA) in southern Sweden.Methods: The study area is the region of Skane in southern Sweden with a population of 1,3 million inhabitants (36% aged ⩾50 years). To be included in the study, patient should fulfil the following criteria: 1) diagnosed with TAB+GCA after 1997, 2) living in Skane at date of diagnosis and date of point prevalence (p.p.) on December 31st, 2014, and 3) on oral glucocorticosteroids (GCs) treatment at the date of p.p. (that redeemed at least one GC prescription during 12 months preceding the date of p.p.) The national Swedish prescribed drug register (SPDR) has been used to identify patients still on GC treatment. The SPDR include data on all the purchased prescriptions since July 2005 and data available through October 2015. Using the unique Swedish personal identification number (PIN), the GCA cohort has been linked to the SPDR. Accordingly, for the prevalence estimate, the numerator was all patients with TAB+GCA who fulfil the study criteria and the denominator was all people aged ⩾50 years living in Skane at date of p.p. The ATC-codes of Betamethasone, Dexamethasone, Prednisolone, Prednisone and Methylprednisolone were identified.Results: At the date of p.p. estimate a total of 631 patients were alive and living in the study area. Of them 359 patients were on GCs at date of p.p. according to the study definition. Accordingly, the p.p. of TAB+ GCA per 100 000 inhabitants aged ⩾50 years was 75.3 (95% CI 67.5-83.1); 40.5 (32.2-48.8) for men and 107 (94.2-119.9) for women. The median time of being on GCs (from time of diagnosis to date of p.p.) 2.23 years (IQR 0.96-4.40). The percentage of patients with positive TAB who were alive at date of p.p. without GC treatment was 43.1%.Conclusion: This is the first estimate of prevalence of TAB+GCA from Sweden. Our prevalence estimate takes into account that GCA may be cured with patients no longer regarded as prevalent cases.Disclosures: Lund University (Less)