Study design: Retrospective Cohort Study.
Objective: To assess the predictive value of early C-reactive protein (CRP) trends following diagnosis of spinal epidural abscess (SEA). Non-operative management with intravenous antibiotics has not demonstrated equivalent outcomes with regard to mortality and morbidity. Knowledge of specific patient and disease factors associated with worse outcomes may predict treatment failure.
Methods: All patients treated for spontaneous SEA in a tertiary centre in New Zealand over a 10-year period were followed for at least 2 years. CRP at diagnosis and day 4-5 following treatment initiation was analyzed to determine predictors of CRP reduction of at least 50%. Proportional Cox hazards regression investigated mortality over 2 years.
Results: 94 patients met inclusion criteria and with CRP values available for analysis. Median age was 62 years (+/- 17.7) and 59 (63%) were treated operatively. Kaplan-Meier analysis estimate of 2-year survival was .81 (95% CI .72-.88). CRP reduction by 50% was seen in 34 patients. Patients who did not experience a 50% reduction were more likely to have thoracic infection (27 vs 8, P = .02) or multifocal sepsis (41 vs 13, P = .002). Failure to achieve a 50% reduction by day 4-5 was associated with worse post-treatment Karnofsky scores (70 vs 90, P = .03) and longer hospital stay (25 days vs 17.5 days, P = .04). Cox regression model showed mortality predicted by Charlson Comorbidity Index, thoracic location of infection, pre-treatment Karnofsky score, and failure to achieve a 50% CRP reduction by day 4-5.
Conclusions: Patients who fail to reduce CRP values by 50% at day 4-5 following treatment initiation are more likely to experience prolonged hospital stay, have poorer functional outcome and have greater mortality risk at 2 years. This group has severe illness regardless of treatment type. Failure to achieve a biochemical response to treatment should prompt reassessment.
Keywords: conservative management; epidural abscess; pyogenic spinal column infection; treatment failure.