AB0378 UTILITY AND ACCURACY OF SOUTHEND PRETEST PROBABILITY SCORE IN GCA FAST-TRACK CLINIC: ANALYSIS IN 261 CONSECUTIVE PATIENTS
Authors: J. Ortega, I. Monjo, E. Fernández-Fernández, E. De Miguel
Journal: Annals of the Rheumatic Diseases (2021)

Background: Strategies for early diagnosis of Giant Cell Arteritis (GCA) have been implemented in the last decade in order to reduce the occurrence of blindness, ischemic events and other manifestations of the disease. The Southend pretest probability score (SPTPS) 1 seem to be useful in stratifying and select the referral patients sent to the GCA fast-track clinics. Objectives: The aim of this study was to test the validity and utility of this score in our patients. Methods: Retrospective available data records of all the patients referred to our GCA fast-track clinic in the last three years were collected. The clinical and laboratory features at referral were evaluated, and the SPTPS was generated. All patients had ultrasound of cranial and large vessel examination (axillary, subclavian and carotid arteries). GCA diagnosis was confirmed by the doctor after at least six months of follow-up. Quartile frequencies, ROC curves and accuracy of the SPTPS was calculated. Results: 261 patients (180 females) with suspicions of GCA were evaluated in our fast-track clinic. Mean age (±SD) was 76±9.2 years, and C-reactive protein 75.7±68.6 mg/l. The time since the first symptoms was less of 6, 6-12, 12-24 or &gt;24 weeks in 37.5%, 19.9, 12.3 and 15.7 respectively. Mean SPTPS was 11.4±4.4, with values of 9.1±3.2 and 12.9±4.4. The area under the ROC curve was 0.761 (95% confidence interval: 0.703-0.819). PTPS overall showed a 50 th percentile score of 11 and a 75th percentile score of 14. We, therefore, classified “Low Risk” (LR) as SPTPS &lt;11, “Intermediate Risk” (IR) 11–14 and “High Risk” (HR) &gt;14. Of 261 referrals, 156 had GCA with cases categorised as LR (119), IR (91) and HR (51). HR score showed a specificity of 96.2% and in IR the specificity ranged between 86.7 and 94.3% (Table 1). Score below 7 appears in 29 cases with only 8 cases of GCA with a probability of GCA &lt; 5%, more of these cases was associated a large vessel vasculitis: 3 cranial arteritis (CA), 4 large vessel vasculitis (LVV) and 1 mixed pattern (MP). LR score included 72 of the 105 (68.6%) non-GCA cases but 47 of 156 (30.1%) GCA patients (20 CA, 11 LVV and 16 MP). IR risk score included 26 (24.8%) of the non-GCA cases and 65 (41.7%) of GCA patients (31 CA, 13 LVV and 21 MP). Finally HR score had only 7 non-GCA cases and 44 (28.2%) patients with GCA (20 CA, 11 LVV and 13 MP). Mean score in cranial forms was 13.1±4.5 and in large vessel vasculitis 12.8±5.0 (p=0.807). Table 1. Sensitivity and Specificity of SPTPS at different cut-off points Cut-off point Sensitivity 1-Specificity 2 1.000 1.000 3.5 0.994 0.971 4.5 0.987 0.943 5.5 0.987 0.876 6.5 0.949 0.790 7.5 0.897 0.676 8.5 0.846 0.476 9.5 0.750 0.362 10.5 0.679 0.248 11.5 0.538 0.133 12.5 0.449 0.086 13.5 0.353 0.057 14.5 0.218 0.038 15.5 0.147 0.019 16.5 0.128 0.019 17.5 0.077 0.010 19 0.038 0,000 20.5 0.032 0,000 21.5 0.019 0,000 22.5 0.013 0,000 24 0.000 0,000 Conclusion: The SPTPS is helpful to stratified patients sent to the fast-track clinic. Scores below of 7 points has a very low probability to have GCA. The diagnostic probability increases directly with the score. There were minor differences without statistical significance between cranial or large vessel vasculitis patterns in the score. References: [1]Sebastian A, Tomelleri A, Kayani A, Prieto-Pena D, Ranasinghe C, Dasgupta B. Probability-based algorithm using ultrasound and additional tests for suspected GCA in a fast-track clinic. RMD Open. 2020 Sep;6(3):e001297. doi: 10.1136/rmdopen-2020-001297. PMID: 32994361; PMCID: PMC7547539. Disclosure of Interests: Javier Ortega: None declared, Irene Monjo Speakers bureau: Roche, Novartis, UCB, Gedeon Richter, Consultant of: Roche, Elisa Fernández-Fernández: None declared, Eugenio de Miguel Speakers bureau: AbbVie, Novartis, Pfizer, MSD, BMS, UCB, Roche, Grunental, Janssen, Sanofi., Paid instructor for: Janssen, Novartis, Roche, Consultant of: AbbVie, Novartis, Pfizer, Galapagos, Grant/research support from: Abbvie, Novartis, Pfizer