P9. Giant cell arteritis--over diagnosed?

Abstract

Background: GCA is the most common vasculitis in the western world. It typically affects individuals >55 years of age and has significant morbidity from its pathology and its treatment. There are no recent (after 2001) estimates of the occurrence in the UK. The aim of this study was to estimate the occurrence of GCA in the UK. Methods: All temporal artery biopsies performed at the Norfolk and Norwich University hospital between 2003 and 2012 were reviewed. Cases of GCA were included only after careful case notes review with all cases fulfilling 1990 ACR criteria. The general practice (GP) location was noted for each of the included cases. The GP location was grouped into standard local authority boundaries. In cases where the individual practice population lay on a local authority boundary, the practice was classified into the local authority area which held the majority of the registered patients. The population denominator was calculated from national census data. Results: There were 601 temporal biopsies performed at the NNUH between the years 2003 and 2012. Subsequently 267 individuals were diagnosed with GCA (44%); 206 were biopsy positive cases (77.2%). The mean age at diagnosis was 75.4 years; 187 were women (70%). Patients with biopsy positive GCA were significantly older (mean difference 2.4 years CI 0.1, 4.7, P 50 years. Conclusion: The results reveal and estimate of 13.9 per 100 000 people aged >50 years. This is much lower than the estimate from the GPRD study carried out in 2001. Within the GPRD study only three out of a selection of 45 cases that were reviewed had a positive temporal artery biopsy (6.7%) and 10 cases (22.2%) were diagnosed and managed in primary care alone. Assuming an incidence for our study is similar to that of the GPRD then in Norfolk perhaps as many as 50% of cases of GCA are managed in the community without undergoing biopsy before embarking on toxic corticosteroid treatment.