Comparison of Vertebral Osteomyelitis Discitis outcomes in Staphylococcal vs. Non-staphylococcal infections

Introduction: Vertebral osteomyelitis-discitis (VOD) is an insidious infection accounting for 3-5% of osteomyelitis cases annually. Staphylococcus Aureus alone contributes 32-67% of VOD cases and is notoriously associated with adverse clinical outcomes. Our preceding research identifies S. aureus infection as the 3rd most predictive variable out of 50 in an XGBoost model to predict the likelihood of spine surgery in VOD patients.

Methods: We aim to evaluate the differential impact of Staphylococcal versus non-Staphylococcal infections on clinical outcomes like in-hospital mortality, duration of hospitalization, and discharge disposition – to hospice and acute care, using a retrospective cohort design and yield valuable insights to inform prognostication efforts and contribute to personalized patient care strategies.
A retrospective dataset of 514 adult patients (≥18 years) with culture-positive VOD (ICD-10 diagnosis codes M46.2,3,4,5) treated at a single institution between 01/01/2015 and 12/31/2019 was studied. A total of 74 causative organisms were identified, including 7 staphylococcus species. The statistical analysis was carried out in R, two-sided hypothesis testing was performed using R proportion test, and odds ratios and risk ratios were calculated using an epiR package comparing outcomes of staphylococcal (n=110) and non-staphylococcal (n=404) VOD infections.

Results: Staphylococcal infection was associated with a higher risk for discharge to hospice facility (RR 1.02(0.99,1.05), OR 2.08(0.47,9.25)) and discharge to Acute Care Facilities (RR 1.01(0.99,1.05), OR 1.19(0.33,4.24)); and conversely reduced risk of in-hospital mortality (RR 0.92(0.88,0.99), p = 0.015). There was no significant association between infecting species and decision for surgical intervention, length of stay, 30-day readmission, or patient disposition, including hospice discharge or discharge to acute care facilities.

Conclusion : Our study observed an increased association with discharge to hospice or acute rehab. However, there was a correlation between staphylococcus species and reduced in-hospital mortality. Similar prospective analysis can yield valuable insights to guide prompt clinical decision-making and resource allocation based on infecting pathogen.