Validation of the AO Spine Osteoporotic Fracture Classification—effect of geographical region on reliability and reproducibility

Regional differences affect the reliability of the AO Spine-DGOU Osteoporotic Fracture Classification. European participants showed the highest agreement. This study underscores the need for addressing regional factors to improve the system’s global clinical utility. To evaluate the influence of geographic region on the reliability and reproducibility of the AO Spine-DGOU Osteoporotic Fracture Classification System. This study included 320 participants from various global regions who classified 27 cases of osteoporotic vertebral fractures using the AO Spine-DGOU system which categorizes the fractures to 5 subtypes (OF 1–OF 5). Participants underwent training via an online webinar. Interobserver reliability and intraobserver reproducibility were assessed using Fleiss’ kappa coefficient, and agreement with a gold standard committee was evaluated. The classification system showed moderate to substantial agreement with the gold standard globally (initial kappa 0.58, improving to 0.61). European participants had the highest agreement (kappa 0.64 and 0.66). OF4 fractures were most accurately classified, while OF3 fractures showed the least agreement. Intraobserver reliability was highest among European participants. Post hoc analysis indicated significantly better reliability among German-speaking participants compared to other Europeans (kappa 0.79 vs. 0.70, p = 0.0026). The AO Spine-DGOU Osteoporotic Fracture Classification System demonstrates moderate to substantial reliability and reproducibility, with regional differences influenced by factors such as training and clinical experience. This underlines the necessity of proper education adapted to the regional particularities.