Diagnostic performance of the Normandy score for infective endocarditis in native bone and joint infections

Purpose The Normandy score was developed to estimate the risk of typical cardiac lesions of infective endocarditis (IE) among patients with native bone and joint infections (NBJI). The aim of this study was to externally validate the Normandy score for the prediction typical cardiac lesions and IE in patients with NBJI. Methods Retrospective study. Setting This study included adult patients with NBJI (2014–2025). Typical cardiac lesions included vegetations, abscess, leaflet perforation, prosthetic valve dehiscence, aneurysm, pseudoaneurysm, or fistula identified by echocardiography or cardiac CT, and abnormal metabolic activity on [ 18 F]FDG-PET/CT. IE was diagnosed according to the 2023 Duke-ISCVID criteria. The primary outcome was the negative likelihood ratio (NLR), with a threshold of < 0.10 to safely rule out IE or typical cardiac lesions. Results Among 462 NBJI episodes, typical cardiac lesions were identified in 101 (22%) and IE was diagnosed in 151 (33%). The Normandy score classified 415 (90%) episodes as high risk compared to 450 (97%) that actually had echocardiography. Against the typical cardiac lesion reference standard, the NLR was 0.08 (95% CI 0.01–0.56). Against the IE reference standard, the NLR was 0.14 (0.04–0.44). Conclusions In this highly selected population (89% bacteremic, 33% with IE), the Normandy score met the prespecified NLR threshold for typical cardiac lesions, but not for IE overall. Because it classified 90% of episodes as high risk, it would have reduced echocardiography by only 7 percentage points A more discriminatory prediction tool is needed to meaningfully optimize resource utilization in this population.