Pos0692 can the assessment of diagnostic confidence be used as a parameter for image reader’s performance in axial spondyloarthritis? first results of the damact study

Background Early and accurate diagnosis is essential for the further outcome of patients with axial spondyloarthritis (axSpA). The confident interpretation of image data sets plays a special role in the clinical practice is crucial for diagnosing axSpA. Therefore, the own assessment of the diagnostic confidence (DC) in the evaluation of images plays an increasingly important role. For this reason, the current guidelines from the ASAS working group recommend reporting the diagnostic confidence in the radiological report. Objectives The aim of this study was to investigate the validity of self-reported DC on the performance of readers in the diagnosis of axSpA using sacroiliac joint (SIJ) images in X-ray, computed tomography (CT) and magnetic resonance imaging (MRI). Methods In total, 163 subjects were included in this retrospective study. In all subjects, X-ray, CT and MRI of the SIJ were available. In total, 9 readers scored the images for the presence or absence of axSpA. The readers were divided into three equal groups according to their experience in musculoskeletal imaging: inexperienced (0 to 1 year of experience), semi-experienced (3 to 8 years of experience) and experienced group (over 8 years of experience). All readers were blinded to clinical data. The DC was collected during the evaluation of the images on a scale from 0 (not sure) to 10 (very sure). Contingency table analysis was performed to assess the reader’s performance using the clinical diagnosis (axSpA or non-axSpA) as standard of reference. The mean DC’s and standard deviation (SD) were calculated for the correct and incorrect axSpA diagnosis for each readers group separately for X-ray, CT and MRI and their differences were assessed using the unpaired t-tests. Results Overall, 89 patients were diagnosed with axSpA and 56 patients with degenerative SIJ disease previously to the scoring. We included 18 healthy subjects in the scoring. The cumulative correct (right-positive) and incorrect (false-positive) axSpA diagnoses were evaluated separately for the different reader groups with the mean DC values, see also Table 1. We showed that the DC differs significantly for the correct and incorrect diagnosis of axSpA in the semi-experienced and in the experienced group in all modalities. However, in the inexperienced group, no significant difference was obtained between the DC’s in X-ray and CT. Conclusion In this study, we were able to show for the first time that diagnostic confidence is a predictive measurement of the diagnostic performance respective reader in the evaluation of patients with axSpA. This is especially true for the interpretation of MRIs, which showed significant differences in all reader groups. Based on these findings, we hypothesize that the addition of diagnostic confidence in radiological findings is a reliable tool to predict diagnostic performance. Table 1. Results. DC = diagnostic confidence. SD = standard deviation. n = cumulative number of correct or incorrect axSpA diagnosis. Correct axSpA diagnosis Incorrect axSpA diagnosis P value X-ray n n Unexperienced (mean DC ± SD) 109 (6.29 ± 1.89) 60 (6.20 ± 1.71) 0.75 Semi experienced (mean DC ± SD) 164 (6.65 ± 2.65) 64 (5.81 ± 2.10) 0.007 Experienced (mean DC ± SD) 173 (7.94 ± 1.82) 61 (6.79 ± 2.24) <0.0001 CT n n Unexperienced (mean DC ± SD) 166 (7.15 ± 1.74) 21 (6.78 ± 1.72) 0.10 Semi experienced (mean DC ± SD) 206 (8.38 ± 1.53) 22 (6.77 ± 2.22) <0.0001 Experienced (mean DC ± SD) 202 (9.16 ± 1.43) 11 (7.18 ± 2.10) <0.0001 MRI n n Unexperienced (mean DC ± SD) 184 (6.97 ± 1.85) 55 (5.80 ± 1.95) <0.0001 Semi experienced (mean DC ± SD) 210 (8.18 ± 1.48) 54 (6.30 ± 1.68) <0.0001 Experienced (mean DC ± SD) 208 (9.14 ± 1.67) 25 (6.72 ± 2.32) <0.0001 REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests Sevtap Tugce Ulas Grant/research support from: STU reports funding from the Berlin Institute of Health (BIH) during the conduct of this study (Junior Digital Clinician Scientist Programme)., Felix Radny: None declared, Katharina Ziegeler Grant/research support from: KZ reports funding (research grant) from the Assessment of Spondyloarthritis international Society (ASAS) during the conduct of this study., Iris Eshed: None declared, Juliane Greese: None declared, Dominik Deppe: None declared, Carsten Stelbrink: None declared, Denis Poddubnyy: None declared, Torsten Diekhoff Speakers bureau: RD reports personal fees from MSD, Novartis and Eli Lilly., Grant/research support from: TD reports funding from the Berlin Institute of Health (BIH) during the conduct of this study.