POS1381 ULTRASONOGRAPHIC EVALUATION OF ENTHESOPATHY IN IDIOPATHIC DIFFUSED SKELETAL HYPEROSTOSIS. APPLICABILITY OF THE MASEI INDEX

Abstract

BackgroundIn Diffuse idiopathic Skeletal Hyperostosis (DISH) o Forestier-Rotés disease the enthesis is also the hallmark of extraspinal manifestations. Despite being a characteristic hallmark of the disease, it has been poorly investigated.ObjectivesTo assess the usefulness of the Madrid Sonographic Enthesitis Index (MASEI) to classify patients with DISH and to analyse the ultrasound findings in hyperostotic entheses.MethodsWe recruited 35 patients with DISH, according to Resnick classification criteria, who were compared with 33 healthy patients age, sex and body mass index-matched. An ultrasound was performed strictly following the MASEI protocol. The ultrasound examiners, with extensive experience in musculoskeletal ultrasound (ECOCAT group), were blinded to the diagnosis of the patients. The interobserver reliability of MASEI index measured by an ICC was 0.97 (95%, CI 89-99) [1]. Demographic, cardiovascular risk factors, clinical, radiological and MASEI-related variables were collected. We categorized into MASEI- inflammatory (MASEI-I) and MASEI-damage (MASEI-D) as previously published [2]but also into MASEI-DISH, which included the variables of thickness, structure and calcification. In the statistical analysis, patients’ data were depicted by using descriptive statistics and the comparison between groups with the Chi-square test for categorical variables and the T-Student test for numerical variables. The validity of the index was examined using the area under the ROC curve and its corresponding 95% confidence interval (CI). The optimal cut-off point was defined as the one that maximizes sensitivity (S) and specificity. (Spe). The statistical program used was R software.ResultsIn the analysis of the elemental lesions, the alterations in structure, thickness and calcification of the distal quadriceps (DQT) and Achilles tendons (AQT) stood out (p <0.05). In the total MASEI, the ultrasound score of ≥ 16.50 (S80%, Spe 85%), obtained with an AUC of 0.877 (95% CI, 0.79 to 0.96), was the best cut-off to differentiate patients from healthy subjects. In the categorized indices, MASEI-I: cut-off 5.50 (S 89%, Spe 76%) and AUC 0.835 (95% CI 0.73 to 0.94); MASEI-D: 7.50 (S 86%, Spe 76%) and AUC 0.850 (95% CI, 0.75 to 0.94) and MASEI-DISH: 16.50 (S 74%, Spe 91%) and AUC (95% CI 0.76 to 0.95). The total MASEI in the DISH group was 27.46 (SD 14.4) compared to 10.30 (SD 6.4) in healthy controls (p<0.001) as well as in those categorized as MASEI-I, MASEI-D or MASEI-DISH (p <0.001).ConclusionEntheses lesions of the AQT and the DQT mark the differences between DISH and healthy patients. The optimal cut-off point was 16.50, and we did not observe any advantages in establishing MASEI categorizations that could be useful in clinical practice. Although the MASEI is an index designed to classify patients with spondyloarthritis, our study shows that it also allows differentiating DISH patients from healthy subjects. It would also be interesting to analyse the capacity of the MASEI to distinguish DISH from spondyloarthritis.References[1]Moya Alvarado P, et al. Rheumatol Int. 2020.[2]Eder L et al. J Rheumatol. 2014; 41(3): 466-72.This study has received a grant from the Catalan Rheumatology Society (2019)AcknowledgementsInvestigation Unit Sociedad Española de ReumatologíaCatalan Rheumatology Society (Grant)Disclosure of InterestsTeresa Clavaguera Speakers bureau: 2021 Jansen, UCB, Novartis, Marta Valls Speakers bureau: 2021 Lilly, Nordic, Maria Buxó: None declared, MANEL PUJOL BUSQUETS Speakers bureau: abbvie, pfizer, lilly, UCB, Janssen, Novartis, Georgina Salvador Alarcon Speakers bureau: Lilly, Novartis, Roche, abbvie, Sanofi, Eulàlia Armengol Speakers bureau: Novartis, Jansen, Xavier González-Giménez: None declared, Mireia Moreno Speakers bureau: Many: Novartis, MSD, Marta Arévalo: None declared, Vicenç Torrente: None declared, Lourdes Mateo: None declared, Susana Holgado: None declared, Xabier Michelena: None declared, Juan José De Agustín De Oro: None declared, Meritxell Sallés Lizarzaburu Speakers bureau: Lilly, Sanofi, Sonia Mínguez: None declared, ANDRES PONCE FERNANDEZ: None declared, Rosa Morlà: None declared, Paula Estrada: None declared, D Reina-Sanz Speakers bureau: Novartis, UCB, Patricia Moya: None declared, Hector Corominas Speakers bureau: Gebro, Abbvie, Fresenius, Judith Font Urgellés: None declared, Patricia Reyner Speakers bureau: Lilly, Sanofi, Nordic