Introduction:

To assess the association of neutrophil-to-lymphocyte ratio (NLR) with post-stroke pneumonia (PSP) incidence, stroke subtype, severity, and prognosis.

Material and Methods:

Prospective observational study over a 42-month period in a Stroke Unit of a tertiary University Hospital. All patients with acute ischaemic stroke (AIS) were sequentially included. NLR was obtained at admission. Pa-tient characteristics such as stroke subtype, severity and PSP diagnosis were ascertained. Score A2DS2 was used as clinical predictor of PSP.

Results:

521 patients with AIS were identified. The mean age was 76.17 ± 10.16 years years, 46.9% were men. Association was found between NLR and type and severity of stroke (p < 0.01), persisting in stratified analysis after excluding concomitant infection. Patients with higher ratio presented severer neurological deficits at admission, higher mortality, and dependency on discharge (p < 0.01). A logistic regression was performed to ascertain the predictive capacity of NLR (≥3) and A2DS2 (≥6) on the likelihood of developing PSP (p < 0.005). The model explained 17.1% (Nagelkerke R2) of the variance in pneumonia diagnoses, correctly classifying 77.0% of patients with 96.3% specificity. Patients with A2DS2 ≥6 were likelier to develop pneumonia (OR 8.36, p < 0.01). Moreover, patients with NLR ≥3 had higher odds of developing pneumonia (OR 2.35, p < 0.01).

Conclusion:

NLR appears to be related to severity in AIS, possibly as surrogate of neuroimmune mediation. Advances in the understanding of the immunobiological effects of ischemia in the brain may lead to future therapeutic developments. Presently, as a relatively inexpensive biomarker, there may be a potential role for NLR in improving PSP prediction scores.

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