Comparative cost-effectiveness of cross-sectional imaging strategies in the diagnosis of intervertebral disc extrusion in dogs: a United Kingdom-based decision-analytic study.

Abstract

BACKGROUND: Cross-sectional imaging, with particular regard to computed tomography (CT) and magnetic resonance imaging (MRI), has been shown to be accurate in the diagnosis of intervertebral disc extrusion (IVDE) in dogs, with MRI having higher diagnostic accuracy. However, the cost-effectiveness of veterinary diagnostic imaging has not been investigated. HYPOTHESIS/OBJECTIVES: Comparative evaluation of the cost-effectiveness of 5 cross-sectional imaging strategies in the diagnosis of thoracolumbar IVDE. ANIMALS: No live animals were used. METHODS: A probabilistic decision-analytical model was developed based on a hypothetical cohort of dogs suspected to have thoracolumbar IVDE. Five imaging strategies based on a combination of noncontrast CT, CT-myelography (CTM), and MRI were tested (CT-only, noncontrast CT only; conditional-CTM, noncontrast CT followed by CT-myelography if nondiagnostic; unconditional-CTM, noncontrast CT followed by CT-myelography; conditional-MRI, noncontrast CT followed by MRI if nondiagnostic; MRI-only, MRI only). Effectiveness was defined as the probability of a correct diagnosis. RESULTS: Across probabilistic simulations, CT-only and unconditional-CTM were consistently less effective and more costly than other options and therefore were never preferred (strictly dominated). Magnetic resonance imaging-only was less cost-effective than strategies based on noncontrast CT (extendedly dominated). Conditional-CTM and conditional-MRI provided the best balance of diagnostic accuracy and cost (the non-dominated efficient set of strategies). CONCLUSIONS AND CLINICAL IMPORTANCE: Conditional imaging strategies beginning with noncontrast CT and escalating only if nondiagnostic were the most cost-effective strategies in diagnosing thoracolumbar IVDE in dogs. An MRI-only strategy was rarely cost-effective despite similar diagnostic sensitivity. From this decision-analytic modeling study, strategic use of cross-sectional imaging in the diagnosis of thoracolumbar IVDE has the potential to optimize the use of finite resources.