To investigate the value and influence of high sensitivity C-reactive protein (hs-CRP) and neutrophil/lymphocyte ratio (NLR) on diagnosis and prognosis of acute ischemic stroke (AIS) related infection.

The clinical data (including follow-up) of 120 patients with AIS diagnosed and treated in the Central Hospital of Enshi Autonomous Prefecture from January 2017 to June 2019 were analyzed, retrospectively, the 120 patients were divided into infection group (34 cases) and non-infection group (86 cases) based on whether had infection within one week of onset (lung infection and urinary tract infection were dominated). The changes of plasma hs-CRP and NLR between infection group and non-infection group were compared, and the diagnostic value of hs-CRP and NLR in AIS-related infections were analyzed by receiver operator characteristic curve (ROC). The effects of hs-CRP and NLR on AIS-related infections were analyzed by Logistic regression analysis. According to the modified Rankin Scale (mRS), 34 patients with infection were divided into good prognosis group (10 cases, mRS ≤ 2) and poor prognosis group (24 cases, mRS > 2). The differences between CRP and NLR were plotted as ROC to explore the predictive value in the prognosis of AIS-related infections. The impact of hs-CRP and NLR on the poor prognosis of AIS-related infections were analyzed by Cox regression analysis.

There was no significant difference in plasma hs-CRP [(7.28 ± 2.35) mg/L vs. (7.16 ± 2.11) mg/L] and NLR [ (4.06 ± 0.91) vs. (3.81 ± 0.85)] between patients of infection group and non-infection group on the second day after enrolled (t = 0.272, P = 0.786; t = 1.423, P = 0.157), but on the fifth day and the seventh day, the plasma hs-CRP [ (15.63 ± 3.88) mg/L and (24.37 ± 4.95) mg/L] and NLR[ (6.22 ± 1.73) and (7.82 ± 2.64)] of patients in infection group were significantly higher than those of non-infection group [hs-CRP: (7.89 ± 2.42) mg/L and (8.45 ± 2.61) mg/L, NLR: (4.16 ± 0.92) and (4.43±1.07)], with significant differences (hs-CRP: t = 13.160, P < 0.001, t = 22.916, P < 0.001; NLR: t = 8.454, P < 0.001; t = 10.047, P < 0.001). The levels of hs-CRP (F = 165.200, P < 0.001) and NLR (F = 33.660, P < 0.001) of patients in infection group on the second, fifth and seventh day after enrolled were significantly different. The levels of hs-CRP (F = 6.306, P = 0.002) and NLR (F = 9.187, P < 0.001) of patients in non-infection group on the second, fifth and seventh day after enrolled were significantly different. ROC analysis showed that both hs-CRP (AUC: 0.634, 95%CI: 0.593-0.688) and NLR on the 2nd day of admission could diagnose AIS-related infections (AUC: 0.685, 95%CI: 0.641-0.734), but the value of the two indexes combination was higher (AUC_hs-CRP+NLR vs. AUC_hs-CRP: Z = 9.645, P < 0.001; AUC_hs-CRP+NLR vs. AUC_NLR: Z = 8.211, P < 0.001; AUC_hs-CRP vs. AUC_NLR: Z = 1.536, P = 0.629), while the sensitivity (64.2% and 63.8%) and specificity (60.7% and 65.1%) increased to 85.7% and 81.4%, respectively. According to Logistic regression analysis, for every 5 mg/L increase of hsCRP and 2.00 increase of NLR on the 2nd day of admission, the risk of AIS related infection increased 1.295 and 1.903 times (P = 0.027, P = 0.001). The plasma hs-CRP of patients in good prognosis group and poor prognosis group were (22.45 ± 3.15) mg/L and (26.23 ± 4.47) mg/L, respectively (t = 2.425, P = 0.021); NLR were (6.51 ± 1.74) and (8.39 ± 2.05), respectively (t = 2.538, P = 0.016), with significant differences. ROC analysis showed that both hs-CRP (AUC: 0.572, 95%CI: 0.544-0.621) and NLR (AUC: 0.641, 95%CI: 0.612-0.684) on the 7th day of admission could predict the prognosis of AIS-related infections, but the value of the two indexes combination was higher (AUC_hs-CRP+NLR vs. AUC_hs-CRP: Z = 9.645, P < 0.001; AUC_hs-CRP+NLR vs. AUC_NLR: Z = 8.211, P < 0.001), the sensitivity (65.4% and 60.2%) and specificity (64.9% and 67.4%) increased to 84.3% and 80.1%, respectively. Cox regression analysis showed that for every 2 mg/L increase of hs-CRP and 1.50 increase of NLR on the 7th day, the risk of poor prognosis of AIS related infection increased by 1.423 and 1.784 times, respectively (P = 0.022, P = 0.009).

hs-CRP and NLR had a certain value in the diagnosis of AIS related infection and prediction of prognosis. To a certain extent, the increase of the above indicators could increase the risk of AIS related infection and poor prognosis, which had a certain clinical value.