Patients with extensive brain infarcts are at increased risk for stroke-associated respiratory tract infections (SARTI), which cause worse outcome. The benefit of general antibiotic prophylaxis is controversial. Early diagnosis of SARTI may improve patient selection for antimicrobial therapy. Procalcitonin (PCT) is widely recognized as serum marker for bacterial infections. Its diagnostic value with respect to SARTI has not been assessed systematically.
Serum PCT levels were analyzed in ischemic stroke patients (n = 50) at day 1 (d1) and day 4 (d4) after stroke onset. PCT test performance was assessed by receiver operator characteristics (ROC) curve analysis. Multivariable logistic regression analysis was applied to identify early predictors for SARTI.
Higher d4 serum PCT levels were associated with SARTI; ROC curve analysis revealed an area under the curve (AUC) of 0.79 (95%-confidence interval (CI) 0.61–0.96). A 0.25-ng/ml cutoff resulted in a test sensitivity and specificity of 42 and 96%, respectively. Positive (LR+) and negative (LR−) likelihood ratios were 10.8 and 0.6, respectively. In predicting SARTI, multivariable logistic regression analysis controlling for infarct volume ruled out an independent explanatory effect of serum PCT. Greater infarct volume (odds ratio (OR) 1.06, 95%-CI 1.02–1.1) prevailed as independent SARTI-predictor.
In the absence of clinical signs, post-stroke screening for SARTI using serum PCT levels is not useful since test sensitivity is low. If the clinical suspicion for SARTI is strong, serum PCT-testing (>0.25 ng/ml) may improve diagnostic accuracy by improving specificity.
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Area under the curve
Central nervous system
Day 1 post-stroke
Day 4 post-stroke
Glasgow coma scale
Human leukocyte antigen-DR
Negative likelihood ratio
Positive likelihood ratio
Lower respiratory tract infection
Magnetic resonance imaging
National Institute of Health Stroke Scale Score
Receiver operator characteristics
Stroke-associated respiratory tract infection
Stroke-induced immune depression
White blood cell count
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This study was supported by a grant from the Else Kröner Fresenius Stiftung to R.V. R.V. is supported by an Else Kröner Memorial scholarship.
Authorship responsibility and contributions
Andreas Hug conceived and designed the research, enrolled patients, acquired/analyzed clinical data/blood specimens, performed statistical analysis and drafted the manuscript.
Bettina Mürle performed brain MRIs/volumetric analysis of brain infarcts and made critical revisions of the manuscript for important intellectual content.
Alexander Dalpke analyzed clinical data/blood specimens and made critical revisions of the manuscript for important intellectual content.
Markus Zorn analyzed blood specimens and made critical revisions of the manuscript for important intellectual content.
Arthur Liesz analyzed clinical data and made critical revisions of the manuscript for important intellectual content.
Roland Veltkamp designed the research, handled funding and supervision and made critical revisions of the manuscript for important intellectual content.
The study was performed at the University Hospital Heidelberg, INF 400, 69120 Heidelberg, Germany.
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Hug, A., Mürle, B., Dalpke, A. et al. Usefulness of Serum Procalcitonin Levels for the Early Diagnosis of Stroke-Associated Respiratory Tract Infections. Neurocrit Care 14, 416–422 (2011). https://doi.org/10.1007/s12028-009-9325-6
- Acute ischemic stroke
- Respiratory tract infection