Long-term functional outcome in pyogenic spinal infection

Abstract

Study design: Retrospective.

Objective: To assess long-term adverse functional outcome following pyogenic spinal infection using standardized outcome measures, Oswestry disability index (ODI), and medical outcomes study short form-36 (SF-36).

Summary of background data: There is minimal published data regarding the long-term functional outcome in pyogenic spinal infection. Previous studies have used heterogeneous, unreliable, and nonvalidated measure instruments yielding data that is difficult to interpret.

Methods: All cases of pyogenic spinal infection presenting to a single institution managed operatively and nonoperatively from 1994 to 2004 were retrospectively identified. Follow-up was by clinical review and standardized questionnaires. Inclusion in each case was on the basis of consistent clinical, imaging, and microbiology criteria.

Results: Twenty-nine cases of pyogenic spinal infection were identified. Twenty-eight percent were managed operatively and 72% with antibiotic therapy alone. Nineteen patients (66%) had an adverse outcome at a median follow-up of 61 months, despite only 5 patients (17%) having persistent neurologic deficit. A significant difference in SF-36 physical function scores was observed between patients with adverse outcome and patients who recovered (P = 0.003). SF-36 scores of all patients, regardless of management or outcome, failed to reach those of a normative population. A strong correlation was observed between ODI and SF-36 physical function scores (rho = 0.61, P < 0.05). Seventeen percent (n = 5) of admissions resulted in acute sepsis-related death. Delay in diagnosis of spinal infection (P = 0.025) and neurologic impairment at diagnosis (P < 0.001) were significant predictors of neurologic deficit at follow-up. Previous spinal surgery was associated with adverse outcome in patients requiring readmission within 1 year of hospital discharge following first spinal infection (P = 0.018). No independent predictors of adverse outcome, persistent neurologic impairment, readmission within 1 year, or acute death were identified by logistical regression analysis.

Conclusion: High rates of adverse outcome detected using SF-36 and ODI suggest under-reporting of poor outcome when American Spinal Injury Association score alone is used to qualify outcome.