Role of the leukocyte antisedimentation rate in prediction of early recognition of post-stroke infection

Introduction

Patients with stroke are more susceptible to bacterial infections that indicate early immune responses, especially those by leukocytes. The leukocyte antisedimentation rate (LAR), a simple test to detect activation of leukocytes, was therefore serially examined and correlated with high-sensitivity C-reactive protein (hsCRP), S100b, procalcitonin (PCT) and outcome in patients with acute ischemic events.

Methods

Venous blood samples were taken serially for measuring the LAR, S100b, hsCRP and PCT within 6 hours after the onset of first symptoms (T0), at 24 hours (T24) and at 72 hours (T72). After 24 hours, enrolled patients were categorized into acute ischemic stroke (AIS) and transient ischemic attack (TIA) groups, based on clinical and imaging data. The LAR and hsCRP were also obtained in 61 healthy volunteers. For statistical analysis, the Wilcoxon test, Spearman correlation, ROC analysis and Mann–Whitney U test were used.

Results

The LAR measured on admission (T0) was significantly higher in patients with acute ischemic events (AIS, n = 38 and TIA, n = 11) compared with healthy controls (median, IQR: 0.329, 0.212 vs 0.159, 0.218 vs 0.060, 0.069, respectively; P < 0.001, P = 0.002). In addition, the LAR was significantly higher at T0 in AIS patients compared with patients with TIA (median, IQR: 0.338, 0.204 vs 0.149, 0.168, P < 0.05). When the LAR was serially analyzed in the AIS group, a significant decrease in the LAR at T24 was found in 10 patients complicated by post-stroke infections (P = 0.028). The cutoff value of the LAR at T24 differentiating patients with high risk of post-stroke infections was found to be 25.6% with a sensitivity of 81.5% and a specificity of 60% (AUC: 0.728, P = 0.035). The cutoff value of LAR24 for predicting poor outcome (defined by Glasgow Outcome Scale ≤ 3) was found to be 26.4% with a sensitivity of 84.2% and a specificity of 53% (AUC: 0.728, P = 0.020). We also observed a positive correlation between S100b and the LAR, hsCRP at 72 hours (P < 0.05).

Conclusion

The simple LAR test was capable of separating individuals with definitive ischemic stroke from those with TIA within 6 hours after onset of symptoms and to select patients with AIS at T24 who are at high risk for post-stroke infection. Our results indicate a very early and rapid activation of innate immune responses in stroke correlating with the size of infarct, and suggest that lack of elevation in the LAR could be related to an increased risk of infection due to a dysregulated activation of leukocytes.