Development of Tuberculosis Spine Instability Score (TSIS)

Study Design. An expert-panel consensus-based content validation and case-based clinical validation study. Objective. To develop a novel scoring system for diagnosing instability in tuberculosis (TB) spine using an expert-panel consensus followed by clinical validation for validating the content. Summary of Background Data. Currently, diagnosis of instability is primarily experience-based which may lead to considerable variability and misdiagnosis in the hands of a relatively in-experienced spine surgeon. Considering the potential complications this entity entails, a universally accepted scoring criteria is very important for accurate and uniform diagnosis of instability in TB spine. Methods. The development of TB spine instability score (TSIS) followed a two-step process, one designing the instrument and the other obtaining judgemental evidence. For judgemental evidence a panel of experts was appointed to make appropriate modifications and content validation for finalizing the scoring instrument. This score was applied on 30 patients of TB spine and receiver operating characteristic (ROC) curves were drawn for sensitivity and specificity analysis. Results. The comprehensive scoring criteria to diagnose instability in TB spine was approved after three rounds of expert panel discussions with an index of content validation more than 0.75 after final round of panel discussion. On case-based validation after plotting ROC curves, sensitivity and specificity for diagnosing stable and potentially unstable lesions at a cut-off score of 6 was 92.9% and 86.8% respectively whereas for diagnosing potentially unstable and unstable lesions at a cut-off score of 10 was 94.3% and 81.9%, respectively. Conclusion. TSIS is a comprehensive scoring system integrating demographic, anatomical, clinical, and radiological factors aimed at diagnosing instability in TB spine. The classification determines indications for surgical stabilization in patients with TB spine, with no or little neurological deficit. Level of Evidence: 4