Dynamic monitoring of the neutrophil/lymphocyte ratio could predict the prognosis of patients with bloodstream infection

Abstract

To explore the value of dynamic monitoring of the neutrophils/lymphocyte ratio (NLR) in peripheral blood for the prognosis of patients with bloodstream infection (BSI). A retrospective study was conducted. 205 patients who were ≥18 years old, their length of hospital stay>24 hours, and they were treated in the China-Japanese Friendship Hospital from January 2013 to October 2014 were enrolled. According to the 28-day survival, the patients were divided into survival group (n=160) and death group (n=45). The white blood cell (WBC), neutrophils count (NEU), neutrophils ratio (Neut%), lymphocyte count (LYM), lymphocyte ratio (Lym%), and NLR in peripheral blood were recorded at 1, 3, 7 days after admission. Receiver-operating characteristic curve (ROC) was plotted for evaluating the value of these factors on the 28-day prognosis, and logistic regression analysis was used to evaluate the risk factors for predicting the outcome. (1) On the 1st day, WBC, NEU, Neut%, NLR, and procalcitonin (PCT) in the death group were significantly higher than those in the survival group [WBC (×10(9)/L): 15.28±8.23 vs. 11.58±6.55, NEU (×10(9)/L): 13.34±7.53 vs. 10.03±5.31, Neut%: 0.886±0.076 vs. 0.845±0.102, NLR: 21.20 ( 13.10, 28.80) vs. 12.08 (6.81, 20.47), PCT (μg/L): 3.13 (0.85, 10.12) vs. 1.34 (0.36, 5.81), P<0.05 or P<0.01], while hemoglobin (Hb), platelet count (PLT), albumin (ALB) content were significantly lower than those of the survival group [Hb (g/L): 86.09±19.83 vs. 107.89±22.82, PLT (×10(9)/L): 157.51±117.81 vs. 195.44±97.28, ALB (g/L): 24.11±6.94 vs. 31.99±6.89, P<0.05 or P<0.01]. On the 3rd day and 7th day, WBC, NEU and NLR in the death group were significantly higher than those of the survival group [WBC (×10(9)/L): 16.61±10.25 vs. 8.91±4.93, 16.05±9.46 vs. 8.79±4.45; NEU (×10(9)/L): 14.15±9.98 vs. 6.97±4.64, 14.36±9.03 vs. 6.59±4.07; NLR: 24.13 (8.49, 38.26) vs. 5.52 (3.58, 8.87), 17.74 (10.74, 32.85) vs. 4.35 (2.78, 7.27), all P<0.01 ], and the LYM and Lym% were significantly lower than those in the survival group [LYM (×10(9)/L): 0.61 (0.38, 1.04) vs. 1.05 (0.78, 1.43), 0.69 (0.35, 0.92) vs. 1.37 (0.93, 1.76); Lym%: 0.039 (0.024, 0.101) vs. 0.135 (0.094, 0.186), 0.056 (0.033, 0.082) vs. 0.170 (0.108, 0.237), all P<0.01]. (2) It was shown by ROC curve that the maximum area under the ROC curve (AUC) of WBC, NEU, Neut%, LYM, Lym%, and NLR about prognosis of BSI were observed on 7 days (0.777, 0.819, 0.905, 0.755, 0.880, 0.887). Based on Neut%>0.855 on the 7th day as a predictor of cut-off value of death in 28 days, the sensitivity was 78.8%, specificity 89.1%, respectively. When Lym%<0.088 on the 7th day as a predictor of cut-off value of death on 28 days, the sensitivity was 89.5%, and specificity was 83.9%. When NLR>10.34 on the 7th day as a predictor of cut-off value of death in 28 days, the sensitivity was 81.8%, and specificity was 91.0%. (3) Survival analysis showed that the 28-day survival rate in the patients with 7-day NLR<10.34 was significantly higher than that in those with 7-day NLR>10.34 (95.0% vs. 34.1%, χ2=82.650, P=0.000). (4) It was shown by multi-factor logistic regression analysis that the levels of 1-day Hb and 7-day NLR were the independent prognostic predictors of 28-day mortality [Hb: odds ratio (OR)=0.946, 95% confidence interval (95%CI)=0.913-0.981, P=0.003; 7-day NLR: OR=34.941, 95%CI=8.728-139.884, P=0.000]. The trend of changes in NEU, LYM and NLR as shown by repeated routine blood examinations contributes to prediction of the outcome of patients with BSI. The levels of 1-day Hb and 7-day NLR are the independent prognostic predictors for 28-day mortality.