OA34 To determine the diagnostic test accuracy of different ultrasound diagnostic criteria in the diagnosis of giant cell arteritis: a secondary data analysis

Abstract

Abstract Background/Aims To determine the diagnostic test accuracy of compression ultrasound compared to combined compression and halo techniques in the diagnosis of giant cell arteritis. Methods A retrospective secondary data analysis was conducted of 111 consecutive patients referred with suspected giant cell arteritis (GCA). All patients had an ultrasound of superficial temporal arteries using halo and compression techniques. All had a temporal artery biopsy (TAB), directed by clinical suspicion. Diagnosis was confirmed at six months based on clinical diagnosis. Exclusion criteria included flare, or relapsing patients. Two by two frequency tables were used to calculate sensitivity, specificity, positive and negative predictive values, positive and negative likelihood ratios of compression and combined halo and compression in comparison to TAB results and clinical diagnosis at six months. Multiple logistic regressions were calculated adjusting for the identified confounders of gender, steroid dose at time of ultrasound and ischemic symptoms of jaw claudication, transient or permanent vision loss. Local NHS Trust Caldicott approval was given for this study. Results Of the 111 patients referred, 56 were clinically diagnosed with GCA. A positive TAB result was recorded in 33. Compression ultrasound had a high sensitivity of 90.6 % (95%CI 75.0, 98.0) but a low specificity of 32.9 % (95% CI 22.8, 44.4) when compared to TAB. Compression had a sensitivity of 83.6% (95% CI 71.2, 92.2) and specificity 34.5% (95% CI 22.2, 48.6) when compared to clinical diagnosis. This is in contrast to compression and halo combined, which had a sensitivity of 71.9% (95% CI 53.3, 86.3) when compared to TAB and 56.4 % (95% CI 42.3.69.7) when compared to clinical diagnosis. However, specificity of the combined techniques was much higher (73.4% [95% CI 62.3, 82.7] and 76.4% [95% CI 62.3, 86.38]) when compared to TAB and clinical diagnosis respectively. A summary of results can be seen in Table 1. Conclusion Compression ultrasound has a high sensitivity; this coupled with the relatively high negative predictive value suggests compression ultrasound may be useful in screening and stratification of patient management. The perceived ease of compression ultrasound suggests further evaluation of compression ultrasound in clinical practice is required. Disclosure K. Smith: Grants/research support; HEE/NIHR Pre-doctoral clinical academic fellowship. B. Sarker: None. J. Lim: None. C. Burnett: None. D. Taze: None. A. Chakrabarty: None. R.J. Wakefield: None. S.L. Mackie: Consultancies; SLM has provided consultancy on behalf of her institution for Roche/Chugai, Sanofi, AbbVie and AstraZeneca. Honoraria; SLM has given talks on behalf of her institution for Pfizer, Vifor and UCB. In all cases fees were paid to her institution and no personal fees were received. Grants/research support; SLM has been an investigator on clinical trials for Sanofi and GSK. As a research grant co-applicant, SLM has received research funding (partial salary support) from Vifor, paid to her institution.