|Year : 2017 | Volume
| Issue : 2 | Page : 79-83
Diagnostic accuracy of neutrophil to lymphocyte ratio in prediction of nonsevere preeclampsia and severe preeclampsia
Rekha Sachan1, Munna Lal Patel2, Vandana1, Pushplata Sachan3, Radhey Shyam4
1 Department of Obstetrics and Gynaecology, King George's Medical University, Lucknow, Uttar Pradesh, India
2 Department of Medicine, King George's Medical University, Lucknow, Uttar Pradesh, India
3 Department of Physiology, Career Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
4 Department of Anesthesiology, King George's Medical University, Lucknow, Uttar Pradesh, India
|Date of Submission||16-Jun-2017|
|Date of Acceptance||05-Sep-2017|
|Date of Web Publication||8-Jan-2018|
Prof. Rekha Sachan
Department of Obstetrics and Gynaecology, King George's Medical University, C-28, Sec-J Aliganj, Lucknow - 226 024, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
Background: Preeclampsia (PE) is a pregnancy specific syndrome characterized by hypertension and proteinuria after 20 weeks of gestation. There is inadequate placentation due to a deficiency in trophoblastic invasion which causes placental hypoxia leading to pro-inflammatory cytokine secretion, neutrophil activation, and endothelial dysfunction.
Material and Methods: This prospective case–control study was carried out over a period of 1 year after informed consent and ethical clearance. Total 543 pregnant women were recruited and 43 women were lost to follow up, so 500 pregnant women followed upto 6 weeks after delivery. Out of these 51 women developed hypertensive disorders of pregnancy. 1 subject excluded during analysis since she developed Eclampsia. Thus study comprised of total 50 cases [Group 1(nonsevere PE)-34 cases and Group 2 (severe PE)-16 cases] and 51 healthy pregnant women who were controls. 5 ml venous blood samples were obtained from all the cases and controls. Samples were collected 2 times; first during the enrollment and second sample was collected after the development of disease. Neutrophil, and lymphocyte levels were measured by Medonic M 20, automated cell counter which gives the reading of cell counts, when microlitres of blood pass through it, NL ratio was obtained after reading.
Results: Those women who developed PE during follow-up (Groups 1 and 2) had higher neutrophil to lymphocyte ratio (NLR) than that of the healthy pregnant women even at early gestation. The receiver operating curve showed significant diagnostic accuracy of NLR between controls and nonsevere PE (NSPE) cases (area under the curve [AUC] = 0.75, P = 0.01) at cutoff value of >3.35%, 52.9% sensitivity, and 74.5% specificity. It also showed significant diagnostic accuracy (AUC = 0.894, P = 0.005) between NSPE and severe PE, at a cutoff value of 3.42 with a sensitivity of 81.3% and specificity of 64.7%.
Conclusion: NLR is a promising marker for the prediction of PE and in the detection of severe PE too.
Keywords: Diagnostic accuracy, lymphocyte, neutrophil, preeclampsia, ratio
|How to cite this article:|
Sachan R, Patel ML, Vandana, Sachan P, Shyam R. Diagnostic accuracy of neutrophil to lymphocyte ratio in prediction of nonsevere preeclampsia and severe preeclampsia. J Curr Res Sci Med 2017;3:79-83
|How to cite this URL:|
Sachan R, Patel ML, Vandana, Sachan P, Shyam R. Diagnostic accuracy of neutrophil to lymphocyte ratio in prediction of nonsevere preeclampsia and severe preeclampsia. J Curr Res Sci Med [serial online] 2017 [cited 2018 Dec 17];3:79-83. Available from: http://www.jcrsmed.org/text.asp?2017/3/2/79/222411
| Introduction|| |
Preeclampsia (PE) is a pregnancy-specific syndrome characterized by hypertension and proteinuria after 20 weeks of gestation., In PE, there is inadequate placentation, due to a deficiency in trophoblastic invasion which causes placental hypoxia, pro-inflammatory cytokine secretion, angiogenic, and antiangiogenic factor release. Changes in the immune system are very important in the background of PE. In addition, pro-inflammatory cytokines, neutrophil activation, and endothelial dysfunction are also associated with the pathophysiology of this disease.
Pregnancy is a controlled inflammatory state. It is believed that an excessive systemic inflammatory response is the basis of the clinical manifestation of PE, but the cause of this inflammatory response in normal pregnancy and PE have not yet been fully clarified., Maternal circulating leukocytes are activated in pregnancy and further activated in PE. All major types of leukocyte, such as neutrophil, lymphocyte, and monocytes are activated. Lipids are secreted by the placentas which are responsible for the activation of leukocytes; they circulate through the intervillous space. Because these activated leukocytes re-enter the maternal systemic circulation, they could be responsible for the vascular dysfunction associated with PE.
Neutrophils are usually thought to be the first line of defense against infection at the site of wound. Recent studies reported that neutrophils also infiltrate systemic vascular tissue in women with PE, thus causing vascular inflammation., Maternal neutrophil to lymphocyte ratio (NLR) can be used to predict PE, but there has been small number of researches on the use of the maternal NLR to predict PE as well as the severity of PE., Therefore, the aim of this study was to evaluate the diagnostic accuracy of NLR in prediction of nonsevere PE and severe PE.
| Material and Methods|| |
This was a prospective cohort study, carried out over a period of 1 year in Department of Obstetrics and Gynaecology at King George's Medical University, Lucknow, Uttar Pradesh, India, after informed consent, and ethical clearance from the Institutional Ethics Committee.
Totally 543 pregnant women were recruited for this study at gestation age of 13–20 weeks, who attended the antenatal care unit. All pregnant women were followed till 6 weeks postpartum. 43 pregnant women were lost to follow-up. Of all the 500 patients followed, 51 patients developed hypertensive disorder of pregnancy so finally the study comprised of 50 cases, 34 cases who developed mild PE (Group 1) 16 cases with severe PE (Group 2) and only one case developed eclampsia so this was excluded from the analysis and 51 healthy normotensive controls (Group 3) were selected after proper systematic randomization from those who did not developed PE during follow up period.
Women with multifetal pregnancy, chronic hypertension, diabetes, chronic liver disease, chronic kidney disease, collagen vascular diseases, with major congenital fetal anomalies, cardiovascular diseases, history of smoking and alcohol were excluded from the study. Patients with history of membrane rupture or any infection which could cause alterations in the maternal NLR were also excluded from the study. The diagnosis of nonsevere PE and severe PE was made according to definition of the American College of Obstetrics and Gynaecology 2013 guidelines.
5 ml venous blood samples were obtained from all the cases and controls. Samples were collected twice, first during the enrollment and second sample was collected after the development of disease. Neutrophil, and lymphocyte levels were measured by Medonic M 20, automated cell counter which gives the reading of cell counts, when microlitres of blood pass through it, NL ratio was obtained after reading.
All statistical analysis was done by Statistical Program for Social Sciences (SPSS, version 17, Statistics for Windows, Version 17.0. Chicago: SPSS Inc) software. Statistical comparison was made of the control group and all the PE patients in respect of NLR. The variables were stated as mean ± standard deviation. For comparison of data between the patient and control group, ANOVA test was used. Moreover, for comparing intergroup difference, Tukey test was used. Receiver operating curve analysis (ROC) was plotted to evaluate the diagnostic accuracy for prediction of PE. P < 0.05 was considered as statistically significant.
| Results|| |
Demographic data of all three groups were statistically similar except body mass index (BMI). The mean BMI of severe PE was significantly (P < 0.024) different and higher (25.13 ± 0.96) as compared to controls (22.10 ± 0.52) [Table 1].
|Table 1: Demographic characteristics (mean±standard deviation) of three groups|
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The maternal NLR were measured and compared between 3 groups (recruitment) at 13–20 weeks of gestation. The difference between three groups were statistically significant. Those women who developed PE during follow up (Groups 1 and 2) had higher NLR than that of the healthy pregnant women even at early gestation (P < 0.01) [Table 2]. There was significant intergroup difference between different groups. The difference between group 3 and 1 was <0.006, the difference between group 1 and 2 was <0.001 and difference between group 3 and 2 was <0.001 [Table 3].
|Table 2: Neutrophil to lymphocyte ratio (mean±standard error) of three groups at recruitment (13-20 weeks of gestation)|
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|Table 3: Comparison (P) of mean neutrophil to lymphocyte ratio between groups at 13-20 weeks by Tukey's test|
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The maternal NLR was remeasured in Group 1 and 2 after the development of PE. It was found that NLR further increased significantly after the development of PE, P < 0.001 [Table 4]. Thus, NLR not only can be used to estimate the severity of PE but also can predict the development of preeclampsia since its values are statistically significantly higher even at 13–20 weeks in women who developed PE during follow-up period as compared to controls.
|Table 4: Neutrophil to lymphocyte ratio comparison before and after development of preeclampsia|
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The ROC curve analysis showed significant diagnostic accuracy of NLR (area under the curve [AUC] = 0.75, P = 0.01) at cutoff value of <3.35, it discriminated the controls (Group 3) and nonsevere PE (NSPE) (Group 1) cases with 52.9% sensitivity and 74.5% specificity [Figure 1].
|Figure 1: ROC curve analysis. Diagnostic accuracy of NL Ratio at cut off value of <3.35, to discriminate between controls (Group3) and nonsevere preeclampsia (Group 1)|
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Further, it also showed significant diagnostic accuracy (AUC = 0.894, P = 0.005) when evaluated between Group 1 (NSPE) and Group 2 (severe PE, at a cutoff value of 3.42 it discriminated the two groups with a sensitivity of 81.3% and specificity of 64.7% [Figure 2].
|Figure 2: ROC curve analysis. Diagnostic accuracy of NL Ratio at cut off value of, to 3.42 discriminate between [Non severe preclampsia Group 1 and severe preeclampsia Group 2]|
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| Discussion|| |
In the present study, women with PE had higher NLR as compared to healthy pregnant women even at early gestational age and also after the development of disease. NLR had good diagnostic accuracy to discriminate between healthy controls and nonsevere PE. It also had good discriminatory power between nonsevere PE and severe PE. One study reported AUC for NLR was not significant for prediction of severe PE from mild PE on the other hand. Another study reported NLR value higher in severe PE as compared to healthy nonpregnant controls, but no significance difference between severe PE and healthy pregnant controls and sensitivity for severe PE is 76.7% and specificity is 69%. One author reported postdelivery preeclamptic women had higher NLR. Another author reported higher NLR with PE as compared to healthy pregnant controls. NLR did not influence the onset of early and late onset PE. NLR is important marker with sensitivity 80.1% and specificity 87.3% and NLR can be a marker of PE.
In women with PE neutrophils are activated as they circulate through the intervillous space and are exposed to oxidized lipids secreted by the placenta. Neutrophils obtained from preeclamptic women express significantly more cyclooxygenase-2 than neutrophils obtained from healthy pregnant females or healthy nonpregnant females. However, the background behind biochemical mechanisms responsible for these immune-modulation has not been yet clearly described.
Neutrophils are usually thought to be the first line of defense against infection at the site of a wound. Recent studies reported that neutrophils infiltrate systemic vascular tissue in women with PE, thus causing vascular inflammation., Oylumlu et al. reported a significantly higher NLR in the PE compared to the controls (7.3 ± 3.5 versus 3.1 ± 1.1; P < 0.001). In another study, all classes of leukocytes were activated in maternal circulation of PE, but only neutrophils were found to significantly infiltrate the systemic vasculature. Staining for neutrophils was observed in 70% of vessels in preeclamptic women compared with only 33% of vessels for lymphocytes. There were three times more neutrophils per vessel than lymphocytes. It has been reported that number of neutrophils increase 2.5-fold by 30 weeks of gestation in a normal pregnancy and increase further in patients with PE. This increase in neutrophils during pregnancy might be due to increased levels of colony-stimulating factors. Canzoneri et al. found that the total leukocyte count was significantly increased in women with severe PE compared to women with mild PE and normal pregnant controls. Lurie et al. claimed that the absolute neutrophil count was significantly elevated in PE. The elevation in neutrophils was more prominent in patients with severe PE as compared to mild PE. In our study, women who developed PE during follow-up had higher NLR than that of the healthy pregnant women even at early gestation (P < 0.01), this indicate its usefulness in the prediction of PE. A study done by Yavuzcan et al. reported NLR was significantly higher in the patients with PE than healthy controls. In our study, a significantly high neutrophil/lymphocyte ratio was observed in patients with PE compared to those with healthy pregnancies, even values were higher at recruitment also, means these women can be discriminated at early gestation age by the estimation of NLR. In our study, in addition, NLR was found to be significantly higher in the severe PE compared to the mild PE which suggests that NLR could predict the severity of PE. In another study, NLR was not found to be sufficient in the determination of the severity of PE. Our study is compatible to Salih et al. study where NLR was significantly higher in the severe PE than in the mild preeclampsia (P = 0.032). However, it was emphasized that NLR could be useful in the determination of PE in high-risk pregnancies.
In the present study, diagnostic accuracy for the prediction of PE was determined by ROC analysis. Nearly 52.9% sensitivity and 74.5% specificity were found at cutoff value 3.
35 to discriminate non severe PE from healthy controls and to discriminate nonsevere from severe PE. Sensitivity of 81.3% and specificity of 64.7% was observed at cutoff value of 3.42. Another study reported 79.1% sensitivity and 38.75% specificity at area under curve of 0.568 at cutoff value of 4.01 to discriminate PE from healthy controls. Study done by C. Gezer et al. showed at the cutoff values of NLR ≥3.08; the area under the ROC was 0.716 for NLR predicted PE with the sensitivity of 74.6% and specificity of 70.1%. In another study done by Oylumlu et al., the receiver operating characteristic analysis, NLR ≥4.1 predicted the presence of PE with 83.3% sensitivity and 81.5% specificity.
Thus, NLR might be useful in the prediction of PE as well as it can be used as emerging marker for estimating severity of PE. NLR also had good sensitivity to discriminate between non severe and severe PE. Its predictive value could be used for early diagnosis, timely referral, and intervention to avoid life-threatening complication of PE.
The findings of the current study taken together with those of the previous studies have added value to the use of maternal NLR levels in the determination of the severity of PE.
Limitation of study
Sample size of our study is small. Financialsupport and large study is required for implementation of these result in clinical practice.
| Conclusion|| |
Maternal NLR could be considered as a predictor of PE and alternative marker in the evaluation of the severity of PE. In conclusion, NLR is a promising marker for the prediction of PE and in detection of severe PE too but further supporting trials are needed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]