Combination of CRP, PCT, N%, Bell stage and add milk the day before onset of NEC for predicting surgical necrotizing enterocolitis and their clinical significance


 Objects Necrotizing enterocolitis (NEC) is a severe neonatal disease. The present study aimed to identify risk factors of NEC and predict surgical NEC.Methods According to the modified Bell’s staging criteria, 235 neonates with NEC admitted between Jan 1, 2015 and Sep 30, 2019 were divided into surgical group (n=47) and conservative group (n=188). Data concerning clinical characteristics and therapeutic management were collected. Infection values of WBC, N%, PLT, CRP, PCT were measured before treatment (T0), on the next day after treatment (T1).Results 1. Surgical group were associated with gestational age, small for gestational age, add milk before onset of NEC, hospitalization expense compared to conservative group (p=0.040, 0.048, 0.045, 0.011), in addition to N%0, N%1, PLT1, CRP1 and PCT1 (p=0.049, 0.003, 0.018, <0.001, 0.003). There was significant difference in NEC among Bell stage I, II and III between surgical group and conservative group (χ2=49.358, p<0.001). 2. Regression analysis showed that Bell stage I, II and III NEC (OR 12.331, 6.315, p=0.038, 0.025), N%1 (OR 0.959, p=0.032), CRP1 (OR 0.978, p=0.039) and PCT1 (OR 0.983, p=0.036), add milk before onset of NEC (OR 7.117, p=0.021) were all independent risk factors to predict surgical NEC. 3. The AUC of combined Bell stage I, II and III NEC, N%1, CRP1, PCT1, add milk the day before onset of NEC (P) in predicting surgical NEC was 0.924 (95%CI 0.865~0.983, p<0.001). The ideal cutoff value of P was 0.729, with a sensitivity of 85.7% and specificity of 87.5%.Conclusion Increased Levels of CRP1, PCT1, N%1, Bell stage I, II and III, and add milk the day before onset of NEC are all independent risk factors of NEC, and combined of them can be used to predict the development of surgical NEC.

3 combined of them can be used to predict the development of surgical NEC.

Background
Necrotizing enterocolitis (NEC) is a common critical disease of the gastrointestinal system in neonates. Some severe cases can occur respiratory circulation failure, shock, DIC, perforation of the digestive tract, and some important organs involved,, and even a threat to life. 1 Niemarkt et al and Houben et al. reported that the mortality rate of NEC can even rise to 15% 30%.1-2 Up to 20% to 40% of infants with NEC will need surgical intervention at some point.1 However, early diagnosis and accurately estimating the day that NEC cases will deteriorate and need surgical intervention are still challenging all over the world.1 Besides, a study by Ahle et al. in Sweden with 320 NEC and 3567 controls, found independent negative associations with NEC for maternal weight, preeclampsia, maternal urinary infection, premature rupture of the membranes, and birthweight, which suggested that NEC is a multifactorial disease. 3 Gordon et al4 in American studied a total of 4059 survivors and 1107 infants who died with a diagnosis of medical or surgical NEC, and found that mortality were associated with low gestational age, low platelet count, low hematocrit, high band/segmented neutrophil ratio, earlier day of diagnosis, high birth weight z-score, non-white race, no antenatal steroids in gestations above 24 weeks, absolute lymphocyte count adjusted for gestational age, and absolute monocyte count high and low values. Thus, studying clinical predictive maternal and neonatal factors can contribute to early diagnosis of NEC, and its course and prognosis.
The occurrence of NEC is affected by many factors, such as premature intestinal immature, severe bacterial infection, ischemia and hypoxia, intestinal dysbacteriosis, and even the separation with mother. With continuous improvement of nutrition and feeding strategies for premature infants, severe late onset infection of neonates is significantly more than early infection, and bacterial infection has become the focus of NEC.5-6 Therefore, it is of great clinical significance to discuss and their clinical data and infection indexes were collected and analyzed, respectively. Logistic regression was used to investigate clinical predictors for surgical NEC, and then receiver operating characteristic (ROC) curve was used to further analysis the predictive value for surgery and the best cut-off.

Definition of Parameters
Peripheral venous blood (2 mL procoagulant tube and 2 mL EDTA anticoagulant) was extracted from each group before treatment (T 0 ), the next day after treatment (T 1 ), respectively. XE-2100 fully automatic hematology analyzer and reagent was used to detect blood leukocytes. Vitros-5600 fully automatic biochemical immune analyzer was used to detect CRP, reagent provided by Johnson Company of USA. Mini-VIDAS-1210 fully automatic immunofluorescence analyzer and reagent from BioMerieuxc company in America was used to detect PCT. Statistical Analyses 6 SPSS 25.0 was used to analyze all data. The measurement data of normal distribution was presented as mean and standard deviation (`x ± s). Comparison between two groups was done with independent sample t-test. The non-normal distribution data presented as [P 50 ( P 25 , P 75 )]. Mann-Whitney U test was used to compare the two groups. Categorical variable can be described by rate. The χ 2 test was used for comparison between two groups.
Logistic regression was performed to estimate the independent risk factors of surgical NEC. The regression equation was expressed as ln(P/(1-P) = Constant + B1CRP + B2PCT, in which P represented the predicted probability of surgical intervention, B1, B2 represented the logistic regression coefficients of CRP, PCT, respectively. The ROC curve analyses were used to determine the diagnostic utilities of biomarkers. p value 0.05 was considered statistically significant.
Surgical group were associated with gestational age, small for gestational age, add milk before onset of NEC, hospitalization expense compared to conservative group (p = 0.040, 0.048, 0.045, 0.011) ( Table 1). There was significant difference in NEC among Bell stage Ⅰ, Ⅱ and Ⅲ between surgical group and conservative group (χ 2 = 49.358, p 0.001) ( Table 1). Laboratory values during the acute phase of NEC were described in the table (Table 2). Before treatment, on the next day after treatment, surgical group had a higher level of N% and N% (p = 0.049, 0.003) than conservative group. On the next day after treatment, surgical group had higher PLT, CRP and PCT than conservative group (p = 0.018, 0.001, 0.003). Gestational age, small for gestational age, add milk before onset of NEC, Bell stage Ⅰ, Ⅱ and Ⅲ NEC, N% 0 , N% 1 , PLT 1 , CRP 1 and PCT 1 were enrolled in the logistic regression and the result showed that gestational age, small for gestational age, N% 0 , PLT 1 were not statistically significant (p = 0.563, 0.116, 0.054, 0.171).

Ethics approval and consent to participate
The study protocol was approval by the Research Ethics Commission of the First Affiliated Hospital of Anhui Medical University. The permission letter that allowed access to the medical records for this study was obtained from the hospital management office.

Consent for publication
The patients' guardians have consented to submission of their case reports to the journal, and we have obtained written informed consent.

Availability of data and material
The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Competing interests
The authors report no conflict of interest.

Funding
No specific funding was provided for this study.

Author's contributions
LW contributed to conception of the manuscript and drafted the manuscript. JWH contributed to the obtaining and interpreting of the clinical information. LLW contributed the conception of the manuscript, and made substantial contribution to manuscript revision. All the authors have read and approved the manuscript for publication and agreed to be accountable for all aspects of the work.