Clinical features presented to primary care prior to diagnosis of giant cell arteritis: an electronic health records study

Abstract

Background: Giant cell arteritis (GCA) is the most common form of medium and large vessel vasculitis. This condition is associated with serious complications, such as blindness if left untreated, and is therefore considered a medical emergency. However, GCA remains difficult to diagnose, in part, due to the wide variation of presenting symptoms, resulting in some patients facing significant diagnostic delay.
Aim: To evaluate clinical features experienced by patients prior to a diagnosis of GCA.
Methods: Four studies were undertaken. Firstly, a systematic review and meta-analysis of clinical features previously associated with a diagnosis of GCA. Subsequently using the Clinical Practice Research Datalink (CPRD), the remaining three studies investigated; the trends in incidence of GCA; the association of individual clinical features on the subsequent diagnosis of GCA; and finally, combinations of presenting clinical features prior to a GCA diagnosis.
Results: The systematic review found 30 distinct clinical features, with the strongest pooled association for jaw claudication and elevated ESR. A total of 9205 GCA cases were identified from 1990-2017 in CPRD. Consultation incidence of GCA was 1.46 per 10,000 person-years in 2017. In the CPRD analysis, individual features most strongly associated with GCA prior to diagnosis were headache, hypertension, and visual impairment. Application of latent class analysis (LCA) suggested five distinct patterns of presenting features; polymyalgia rheumatica (PMR), hypertension and multiple other features, single or no feature, hypertension, and elevated ESR.
Conclusion: GCA remains a difficult condition to recognise in primary care. Clinical features, such as headache, PMR, elevated ESR, and hypertension were consistently identified as important clinical features experienced prior to GCA diagnosis. This thesis has highlighted the need to research patterns of clinical features rather than individual features that occur prior to a GCA diagnosis.