Distinguishing laboratory characteristics in giant cell arteritis: a real-world retrospective cohort study

BACKGROUND: Untreated Giant Cell Arteritis (GCA) has the potential to cause serious complications such as vision loss. Appropriate initial assessment by General Practitioners, early treatment and specialist referral are therefore essential in reducing morbidity. However, lack of awareness around the range of presentations can lead to a delay in diagnosis. OBJECTIVE: We aim to evaluate the discriminative diagnostic performance of laboratory characteristics associated with GCA in our population over a period of 18 months. DISCUSSION: This is a real-world retrospective review of patients referred to ophthalmology services with concern for GCA. The pre-test probability of a patient referred with suspected GCA was 13.9% to have GCA, highlighting the need for specialist referrals to continue. White Cell Count (p = 0.01), Platelet Count (p = 0.02), Erythrocyte sedimentation rate (p = 0.004) and C-reactive protein (p = 0.002) were significantly different between GCA and non-GCA cases. Moreover, this study demonstrates that absolute neutrophil count (p = 0.02) can be a useful parameter in initial investigations for GCA.