Preeclampsia is a hypertensive disorder with elevated blood pressure and proteinuria after 20 weeks of gestation, often involving an exaggerated inflammatory response. This study examined the relationship between the neutrophil-to-lymphocyte ratio (RNL) and preeclampsia. A retrospective analytic study with a cross-sectional approach analyzed medical records of 106 inpatients at Zainoel Abidin Hospital Banda Aceh from January to December 2020. Most patients were aged 20–35 years (64.2%), college-educated (38.8%), housewives (68.9%), and multiparas (62%). RNL analysis showed 8.6% normal and 91.4% abnormal in severe preeclampsia cases. The Spearman correlation test showed p=0.367 (p>0.05), indicating no significant relationship between RNL and preeclampsia. The mean RNL was 6.5267 in preeclampsia and 8.3106 in severe cases, both exceeding the normal cut-off of 4.8. There was no relationship between RNL and preeclampsia, but the mean RNL values were above normal.
Preeclampsia is a specific syndrome in pregnancy that can affect all organ systems. According to the American College of Obstetrics and Gynecology (ACOG), preeclampsia is defined by the presence of hypertension (BP > 140/90 mmHg) and proteinuria (>300 mg of protein in 24 hours of collected urine) at gestational age above 20 weeks. (Keman, 2014) The latest classification of preeclampsia no longer divides it into mild and severe preeclampsia but instead categorizes it into preeclampsia with severe features and preeclampsia without severe features. This change reflects the potential for preeclampsia to worsen suddenly. Preeclampsia without severe features is referred to simply as preeclampsia, while preeclampsia with severe symptoms is referred as severe preeclampsia (PEB) (Hidayat et al., 2018).
The World Health Organization (WHO) estimates that cases of preeclampsia in developing countries are seven times higher compared to developed countries.
The prevalence of preeclampsia in developing countries ranges from 1.8% to 18%, while in developed countries, it is between 1.3% and 6%. According to the latest WHO report, preeclampsia accounts for 70,000 maternal deaths annually worldwide, along with 500,000 infant deaths each year as a result of preeclampsia (Purwaningtyas & Prameswari 2017). Hypertension in pregnant women in Indonesia in 2010 (21.5%), in 2011 (24.7%), in 2012 (26.9%), and in 2013 (27.1%). The prevalence of hypertension in pregnant women in Indonesia increases every year, indicating an increased risk of preeclampsia. Lombo et al. (2017) factors contributing to the occurrence of preeclampsia include maternal characteristics such as age, parity, birth spacing, and educational background (Kusumati & Wijayanti 2019). Preeclampsia can cause complications in the mother, namely eclampsia, intrauterine growth restriction (IUGR), HELLP syndrome, renal failure, coagulopathy (disseminated intravascular coagulation), and liver dysfunction (Faiqoh & Hendrati, 2018).
The neutrophil-to-lymphocyte ratio (NLR) is a simple parameter for assessing a person's inflammatory status and has been proven accurate in predicting clinical outcomes in patients with heart disease, ischemic stroke, cancer, sepsis, and pathological infections (Wulandari, 2019). An elevated NLR is known to be associated with disease severity and may be considered an independent biomarker to indicate poor outcomes (Amanda, 2020). RNL can be calculated easily and can be obtained quickly through whole blood examination as part of routine laboratory work (Saputra et al., 2019). The NLR value is obtained by dividing the absolute neutrophil count by the absolute lymphocyte count (Lee et al., 2018). RNL does not require additional examinations or costs because the results are obtained directly from the hemogram. This makes the parameter cost-effective and applicable to all patients (Singgih et al., 2020). The study by Forget et al. aimed to determine the normal value of RNL used as a cut- off value in healthy subjects. RNL values are not influenced by age or gender.
The cut-off value of RNL in a healthy population ranges from 0.78-3.53 (Forget et al., 2017).
The RNL value describes a nonspecific inflammatory mediator as the first line of defense and a protective component in inflammation (Singhal et al., 2019). The study by Abd-Alazim et al. stated that there was an increase in RNL values in preeclampsia patients compared to normal pregnant women and increased significantly in severe preeclampsia (Abd-Alazim et al., 2018). The Indonesian Association of Fetomaternal Medicine (HKFM) stated that the cutoff value for the occurrence of preeclampsia in pregnant women, with a sensitivity of 93% and a specificity of 91%, is 4.8 (Himpunan Kedokteran Fetomaternal Indonesia, 2021). An increased NLR value in preeclampsia indicates systemic inflammation and endothelial dysfunction, which occurs through the interaction of endothelial adhesion molecules and surface receptors on neutrophils. Activated neutrophils will release granules that can mediate vascular damage. Leukotrienes will also be synthesized, and superoxide will be produced. Both of these will trigger blood vessel damage (Prasetyo et al., 2019).
Type of retrospective observational analytic research with a cross sectional approach. he research was conducted in the medical records department using inpatient data from Zainoel Abidin Regional General Hospital in Banda Aceh. Data collection took place in November 2021. The population consisted of inpatients with preeclampsia at Zainoel Abidin Regional General Hospital in Banda Aceh. The study sample included all inpatients with preeclampsia at the hospital from January to December 2020 who met the inclusion criteria: pregnant women with gestational age over 20 weeks and complete laboratory results. Exclusion criteria were patients with a history of blood transfusion before being sampled, incomplete medical records, pregnancy with a history of hypertension, diabetes mellitus, kidney disease, pathological infectious diseases, and a history of gynecological malignancies.
The sampling method used was non-probability sampling with a total sampling technique. The research data were secondary data obtained from medical records at RSUDZA. Data were collected in the form of general characteristics (age, education, occupation, parity) and the ratio of neutrophils and lymphocytes. Analysis was done univariate and bivariate.
| Characteristic | Frequency (n = 106) | Relative Frequency (%) |
|---|---|---|
| 20–35 Years | 68 | 64.2 |
| >35 Years | 38 | 35.8 |
| No Formal Education | 1 | 0.9 |
| Elementary School | 9 | 8.5 |
| Middle School | 17 | 16.0 |
| High School | 38 | 35.8 |
| Higher Education | 41 | 38.7 |
| Housewife | 73 | 68.9 |
| Farmer | 1 | 0.9 |
| Entrepreneur | 11 | 10.4 |
| Government Employees | 21 | 19.8 |
| Primiparous | 18 | 17.0 |
| Multiparous | 42 | 39.6 |
| Grand Multiparous | 46 | 43.4 |
Based on Table 1, the age range of 20–35 years is more dominant, with 68 subjects (64.2%). These results are in line with the study by Kadek et al. in 2015 at Sanglah General Hospital in Denpasar, which showed that the majority of pregnant women with preeclampsia were in the 20–35 year age range, accounting for 76 out of 108 subjects (70.3%) (Budi Juliantari & Sanjaya, 2017). Preeclampsia often occurs in women of productive age due to the high frequency of pregnancies and childbirth within this age range. The results of this study are not in line with the research of Sintia et al in 2017 at Dr. Moewardi Hospital in Surakarta, which stated that there were no significant differences related to the age characteristics of preeclampsia patients. Sintia et al.’s study also showed that the majority of preeclampsia cases were within the 20–35 year age range (Damayanti & Silistyowati, 2019). This is because age affects the increase and decline of bodily functions and human overall health status. Female reproductive organs are immature or underdeveloped at ages of <20 years. The degenerative processes that occur with age lead to the hardening of blood vessel walls, causing the blood vessels to become narrowed in women at the age of >35 years old (Setyawati et al., 2018)
Table 1. shows that the highest level of education among respondents is higher education, with 41 subjects (38.8%). This finding aligns with a study by Yudia et al. in 2015 at Dr. Mohammad Hoesin General Hospital in Palembang, which found that education level did not have a significant relationship with the incidence of preeclampsia (p-value > 0.05). Education is related to a person's opportunity to absorb information about certain matters, such as information on prevention and risk factors for preeclampsia. However, such information does not necessarily have to come from formal education; higher education does not guarantee that someone will avoid preeclampsia (Gusti et al., 2016). The result of this study contrasts with a study by I Nyoman Rake in 2016 at Dr. T.C. Hillers General Hospital in Maumere, which found that the highest number of preeclampsia cases occurred among women with elementary school education, accounting for 51 individuals (45.5%). Education is often associated with knowledge about health, but women with lower educational levels who experience preeclampsia do not necessarily have low knowledge, as they may
acquire information through counseling. Knowledge can also come from people around them or from any media, leading them to pay closer attention to their health by completing antenatal care (ANC) visits (Zam et al., 2021).
Based on Table 1, the majority of respondents were housewives, accounting for 73 subjects (68.9%). This finding aligns with research by Giovanna et al. in 2015 at Prof. Dr. R. D. Kandou General Hospital, Manado, which showed that preeclampsia cases were dominated by mothers working as housewives. A study by Rien et al. in 2013 at the same hospital indicated that mild preeclampsia cases were dominated by housewives, with 67 individuals (84.8%), while severe preeclampsia cases were also dominated by housewives, with 44 individuals (78.5%) (Hutabarat et al., 2016). Research by Yanita et al. in 2018 at Muhammadiyah Bantul Hospital found that preeclampsia cases were prevalent among housewives because women who do not work and have low incomes tend to have poor nutritional quality (Trisetiyaningsih & Smaradika, 2019). Housewives are predominant in preeclampsia cases because this occupation is associated with heavy physical activities that can cause fatigue. Pregnancy also makes women tire more easily, increasing the risk of preeclampsia. This is supported by the theory that occupation is linked to physical activity, which influences muscle function and blood circulation. Changes in blood circulation and blood pressure occur due to the pressure from the growing uterus during pregnancy. The heart's workload increases with gestational age to meet the body's needs during pregnancy (Elsanti, 2020).
Table 1. shows that the majority of respondents were multiparous, accounting for 46 subjects (43.3%). This finding is consistent with a study by Rien et al. in 2013 at Prof. Dr. R. D. Kandou General Hospital, Manado, which reported that the majority of the parity group was multiparous, with 49 individuals (62%).(24) A study by Dewi Hermawati in 2020 at a hospital in Banda Aceh found no significant relationship between parity and the incidence of preeclampsia (p- value > 0.05), with 63 multiparous individuals (71.6%) and 25 primiparous individuals (29.4%) (Hermawati, 2020). However, the results of this study differ from the findings of Dini et al. in 2019 at Dr. Abdoer Rahem General Hospital, where the majority of parity cases were primiparous, with 241 subjects (54.6%) (Kurniawati et al., 2019). According to theory, nulliparous women are at higher risk for developing preeclampsia, as preeclampsia often occurs in women who are exposed to chorionic villi for the first time. Immunologically, this can arise due to incomplete formation of blocking antibodies, specifically HLA-G, against placental antigens during a first pregnancy. This leads to impaired trophoblast implantation in the maternal decidual tissue. Consequently, endothelial cells in the placenta produce less prostacyclin, a vasodilator, while releasing more thromboxane, resulting in vasoconstriction (Kusumawati & Wijayanti, 2019).
RNL in preeclampsia patients can be seen in Table 2. below.
Distribution of Neutrophil and Lymphocyte Ratio Values and Preeclampsia Features
| Frequency (n = 106) | Relative Frequency (%) | |
|---|---|---|
| RNL | ||
| Normal | 35 | 33.0 |
| Abnormal | 71 | 67.0 |
| Features of Preeclampsia | ||
| Preeclampsia | 6 | 5.7 |
| Severe Preeclampsia | 100 | 94.3 |
The results of table 2 shows that 6 subjects (5.7%) had preeclampsia, while 100 subjects (94.3%) had severe preeclampsia. This indicates that cases of severe preeclampsia are more prevalent than cases of preeclampsia. These results show that patients who experience severe preeclampsia are more than preeclampsia. These results are in line with the research of Hernalia et al in 2012 at RSUD Dr. Soetomo Surabaya which states that preeclampsia cases are dominated by severe preeclampsia. This can occur because many pregnant women do not realize they have preeclampsia and do not routinely check their health. Pregnant women tend to come to the doctor when they are already in severe preeclampsia or even have complications of preeclampsia, such as eclampsia (Putri et al., 2015). The results of the study found more cases of severe preeclampsia compared to preeclampsia because the researchers included only inpatient cases and excluded outpatient cases.
The results showed that the ratio of neutrophils and lymphocytes with normal ratios was 35 subjects (33.0%) and abnormal ratio were 71 subjects (67.0%). This indicates that the ratio of neutrophils and lymphocytes is more prevalent in the abnormal ratio. Increased neutrophil and lymphocyte ratios are characterized as a response to inflammatory disorders. The inflammatory process affects the number of leukocytes, neutrophils, and lymphocytes. Initially depicted as an increase in neutrophil values due to stress response, excessive response will induce lymphocyte apoptosis so that lymphocyte values tend to decrease when inflammatory disorders occur (Riandy et al., 2019). These results are in line with the results of a meta-analysis by Kang et al. in 2020 in China which stated that RNL has a higher value in preeclampsia patients, especially in cases of severe preeclampsia (Kang et al., 2020). A study conducted in India by Gogoi et al. in 2019 also showed that women with preeclampsia had higher NLR values, even during the early weeks of pregnancy (Gogoi et al., 2019). However, a different result was reported in a study by Yavuzan et al. in 2014 in Turkey, which indicated that NLR values did not significantly increase in severe preeclampsia cases (Yavuzcan et al., 2018).
Relationship between Neutrophil and Lymphocyte Ratio in Preeclampsia Patients
| Neutrophil and Lymphocyte Ratio | Preeclampsia | Severe Preeclampsia | Total | P Value | |||
|---|---|---|---|---|---|---|---|
| (n) | (%) | (n) | (%) | (n) | (%) | ||
| Normal | 3 | 8.6 | 32 | 91.4 | 35 | 100 | 0.367 |
| Abnormal | 3 | 4.2 | 68 | 95.8 | 71 | 100 | |
Based on Table 3, the Spearman correlation test results showed a p-value of 0.367, indicating that there is no statistically significant relationship between the ratio of neutrophil and lymphocyte (NLR) in preeclampsia patients. The result of this study is consistent with the study by Sweed et al. in 2021 in Egypt, which also found no association between the neutrophil-to-lymphocyte ratio in preeclampsia patients (p-value = 0.17) (3Sweed et al., 20214). However, the study by Panwar et al. in 2019 in India showed different results, demonstrating a significant relationship between the neutrophil-to-lymphocyte ratio and preeclampsia (p-value < 0.001) (Panwar et al., 2019).
Average Neutrophil and Lymphocyte Ratio Values in Preeclamptic Patients
| Mean | n | Std. Deviation | P value | |
|---|---|---|---|---|
| Preeclampsia | 6.5267 | 6 | 3.97556 | |
| Severe Preeclampsia | 8.3106 | 100 | 3.85500 | 0.367 |
The results in Table 4. show that the average the ratio of neutrophils and lymphocytes in preeclampsia patients is 6.5267 and severe preeclampsia is 8.3106. These findings indicate that the NLR values exceed the normal cutoff value of 4.8. This suggests that NLR increases in preeclampsia patients, consistent with the theory that preeclampsia involves an excessive inflammatory response. The study results did not show a significant relationship between preeclampsia without severe features and severe preeclampsia. This finding aligns with the study by Mehmet Toptas et al. in 2016 in Turkey, which reported that NLR values were significantly higher in preeclampsia patients compared to women with normal pregnancies. However, NLR values did not show a significant difference between patients with preeclampsia and those with severe preeclampsia (Toptas et al., 2016).
Preeclampsia is a multisystem organ disorder that leads to organ damage. The etiology of preeclampsia is not clearly understood, but it is hypothesized that the initial pathogenic process involves abnormal placentation, which triggers inflammation in the microvasculature. This microvascular inflammation results in the release of anti-angiogenic factors into the maternal circulation. While the activation of physiological inflammatory pathways occurs in normal
pregnancies, excessive inflammatory activation is observed in preeclampsia. Neutrophil activation, inflammatory cytokine production, and vascular endothelial dysfunction occur in preeclampsia. Increased neutrophil activation results from a response to inflammatory disturbances, while lymphocytes tend to decrease due to lymphocyte apoptosis caused by excessive inflammatory responses (Toptas et al., 2016). Based on this study, the findings contradict the theoretical expectations regarding the NLR values in relation to the development and/or severity of preeclampsia. This study found no significant relationship, with a p-value of 0.367, due to the imbalance between research subjects experiencing preeclampsia and severe preeclampsia. This is supported by the study by Kholief et al. in 2019 in Egypt, which showed no significant relationship between severe preeclampsia and the control group (p-value = 0.169) (Kholief et al., 2019). The study by Oylumlu et al. in 2014 in Turkey indicated that NLR values were significantly higher in preeclampsia patients compared to the control group (p-value < 0.001). However, the Oylumlu study found no significant relationship between NLR values in severe preeclampsia patients compared to those with preeclampsia (p-value > 0.05). This indicates that NLR values cannot determine the severity of preeclampsia in patients but can be useful in identifying preeclampsia in high-risk pregnancies (Oylumlu et al., 2014).
The results of this study differ from the research by Abd-Alazim et al. in 2018 in Egypt, which stated that NLR values were significantly higher in the severe preeclampsia group compared to the preeclampsia group, with a P- value of 0.042. Their findings showed that neutrophil levels in severe preeclampsia were higher than in preeclampsia, while lymphocyte levels were lower in severe preeclampsia compared to preeclampsia. According to receiver operating characteristic (ROC) analysis, the RNL value obtained as a comparison between preeclampsia and severe preeclampsia was 4.77. The RNL value obtained is a value that combines the predictive risk of two leukocyte subtypes, namely “neutrophils and lymphocytes” into a single risk factor. The study conducted by Abd-Alazim et al. concluded that the RNL value can be a marker of the inflammatory status of preeclampsia patients and is useful for determining the severity of preeclampsia (Abd-Alazim et al., 2018).
The study by Kurtoglu et al. in 2015 in Turkey showed that NLR values were significant in the preeclampsia group compared to the control group, with a P-value of 0.023. However, NLR values did not show significant differences when comparing severity, proteinuria levels, subjective symptoms, and the onset of preeclampsia (Kurtoglu et al., 2015). The results of research by Serin et al. in 2016 in Turkey found that the RNL value was higher in the severe preeclampsia group compared to the preeclampsia group, namely p value = 0.032 and a positive correlation between the RNL value and proteinuria (Serin et al., 2016). The research by Widyastiti et al. in 2019 at dr. Kariadi General Hospital compared NLR values between severe preeclampsia and preeclampsia patients, revealing a significant difference with a P-value of 0.000 (Widyastiti & Setianingrum, 2019). The study by Gezer et al. in 2016 in Turkey, based on multivariate regression analysis, showed that NLR values increased in preeclampsia patients (Gezer et al., 2016).
Leukocytes are an important component of the immune system, and play an important role in the pathophysiology of pregnancy-related disorders involving the decidua and placenta. Leukocytes infiltrate the systemic vascular network in women with preeclampsia, causing vascular inflammation. Women with preeclampsia will experience neutrophil activation when neutrophils circulate through the intervillous space circulation and will be exposed to oxidized lipids secreted by the placenta. Oxidized lipids are potent activators of neutrophils leading to the expression of COX-2 which regulates thromboxane release. Women with preeclampsia express significantly more COX-2 than healthy pregnant women. Another theory states that neutrophil activation that occurs in the placental circulation due to hypoxic conditions contributes to increased vascular resistance in women with preeclampsia. This is consistent with more adhesion and endothelial infiltration of neutrophils into the intima of the systemic vascular space while lymphocyte infiltration was found to be insignificant (Singhal et al., 2019).
Based on research conducted in the Medical Records Installation Room at Zainoel Abidin Regional General Hospital in Banda Aceh, it can be concluded that there is no correlation between the ratio of neutrophils and lymphocytes in preeclampsia patients. However, there is an increase in the average NLR value in preeclampsia patients more than the cut-off value of the normal NLR.
It is recommended to routinely evaluate and monitor the NLR value in preeclampsia patients for early detection of abnormal increases, even though there is no direct correlation between the neutrophil-to-lymphocyte ratio.
Future research is recommended to explore the potential role of the neutrophil-to-lymphocyte ratio (NLR) as a predictive or prognostic biomarker in preeclampsia, involving a larger sample size, longitudinal study design, and consideration of confounding factors such as infection, inflammation, and comorbidities that may influence NLR values.