Global Spine Journal - 2026-05-08 - Journal Article
Postoperative C-Reactive Protein Trajectories in Spine Surgery - Influence of Vancomycin Powder: A Secondary Analysis of a Prospective Randomized Controlled Trial.
Panzenböck LF, Abdel Nour G, Dürrschnabel DL, Krepler P
Topics
Key Takeaway
Day 7 CRP ≥79 mg/L predicted SSI after posterior lumbar interbody fusion with AUC 0.813 and NPV 95.2%, while intrawound vancomycin powder did not alter CRP kinetics at any postoperative time point.
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Summary
This secondary analysis of a prospective RCT (NCT02631408) characterized postoperative CRP trajectories in 292 patients undergoing posterior lumbar interbody fusion to identify SSI-predictive thresholds and determine whether intrawound vancomycin powder (1 g) altered CRP kinetics. SSI occurred in 22 patients (7.5%: 9 overt, 13 subclinical); SSI patients showed persistently elevated CRP through day 7 while uncomplicated patients declined after day 3. Day 7 CRP ≥79 mg/L was the strongest predictor (AUC 0.813, NPV 95.2%), with day 3 CRP ≥92 mg/L offering earlier warning (AUC 0.761); vancomycin did not affect CRP at any time point (all P >0.08).
Key Limitation
The secondary-analysis design means the trial was powered for the vancomycin SSI-reduction endpoint, not for CRP threshold discrimination, raising the possibility that the cohort is underpowered to detect subgroup differences in CRP kinetics by fusion level, instrumentation extent, or comorbidity burden.
Original Abstract
Study DesignRandomized controlled trial.ObjectivesTo characterize postoperative C-reactive protein (CRP) trajectories as predictors of surgical site infection (SSI) following lumbar spine surgery, to determine optimal CRP thresholds, and to assess whether intrawound vancomycin powder affects postoperative CRP kinetics.MethodsData were drawn from a prospective randomized controlled trial enrolling 292 patients undergoing posterior lumbar interbody fusion. Patients received intrawound vancomycin powder (1 g) plus standard prophylaxis or standard prophylaxis alone. CRP was measured preoperatively and on days 1, 2, 3, 5, and 7. SSI was classified as overt (CDC criteria) or subclinical. ROC analysis evaluated prediction of any SSI at each time point.Results22 patients (7.5%) developed any
SSI
9 overt (3.1%) and 13 subclinical (4.5%). CRP peaked at day 5 in the overall cohort. SSI patients showed persistently elevated CRP through day 7, while uncomplicated patients declined after day 3. Day 7 CRP showed the highest discriminatory ability (AUC = 0.813; cutoff ≥79 mg/L; sensitivity 61.1%; specificity 91.4%; NPV 95.2%). Vancomycin did not alter CRP kinetics at any time point (all P > 0.08).ConclusionsIn 292 spine surgery patients, day 7 CRP (AUC = 0.813) was the strongest predictor of any SSI. A cutoff of 79 mg/L on day 7 provided NPV of 95.2%, supporting CRP as a rule-out biomarker. Day 3 CRP ≥92 mg/L (AUC = 0.761) offers early warning capability. CRP trajectories did not differ significantly between the vancomycin and control groups. ClinicalTrials.gov: NCT02631408; EudraCT: 2014-002096-29.