Hemogram Parameters and Hemogram-Derived Ratios in Covid-19 Severity

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Introduction
The COVID-19 pandemic, induced by the novel coronavirus SARS-CoV-2, has posed significant challenges to global healthcare systems.Understanding the hematological manifestations of the disease, as reflected in hemogram values, is of paramount importance in terms of patient management and prognosis (1).Hemogram parameters encompassing various metrics offer valuable insights into the pathophysiology and severity of COVID-19.Given that the disease primarily targets the respiratory system, it can also exert systemic effects, including hematological alterations (2).Hemogram values constitute an integral component in evaluating the clinical course and severity of COVID-19.Monitoring these parameters can assist in risk stratification, early intervention, and informed decision-making.As our comprehension of COVID-19 continues to evolve, ongoing research remains crucial for enhancing our understanding of hematological findings and their clinical significance in this pandemic (3).Lymphocyte counts notably decrease, particularly in severe cases of COVID-19.Lymphopenia is regarded as a significant marker of immune dysregulation and an indicator of disease severity.A high neutrophil-to-lymphocyte ratio is associated with an increased risk of severe illness and poor prognosis, reflecting the balance between innate and acquired immune responses (4).Thrombocytopenia (a low platelet count) has been observed in some COVID-19 patients, especially in those with severe disease.Platelet dysfunction can contribute to a prothrombotic state (5).Although not specific to COVID-19, monitoring hemoglobin and hematocrit levels is necessary to assess the overall health status of patients, especially those with comorbidities.Red cell distribution width, which is associated with a worse prognosis in COVID-19 patients, can be used as an indicator of systemic inflammation and impaired oxygenation (6).Identifying patients at risk of developing severe illness in COVID-19 cases is imperative (7).To achieve this goal, it is crucial to identify accurate, simple, and cost-effective prognostic tools for patient classification (8).Common laboratory parameters and inflammatory markers, along with their variations, have been reported in COVID-19 patients (9,10) but their relationship with disease severity is still under investigation (11).The purpose of this article is to review the fundamental hemogram parameters frequently observed in COVID-19 patients and their clinical significance.

Study Population
The study included 1000 individuals diagnosed with COVID-19 by seeking care at a tertiary healthcare center as the thirdtier of referral.Those who did not meet the criteria were excluded from the study, resulting in a study cohort comprising 950 participants.www.cmhrj.com

Exclusion Criteria
• Chronic respiratory disease, • Individuals under the age of 18, • Those who have not had their COVID-19 diagnosis confirmed by Real time-Polymerized Chain Reaction (Rt-PCR), • Those with incomplete laboratory data have been excluded from the study.

Study Design and Participants
Our study is a retrospective and, cross-sectional investigation.
The study data were obtained from hospital records.Laboratory findings of the participants within 30 days following the onset of symptoms were analyzed.Additionally, demographic characteristics, the presence of chronic diseases, and data related to molecular and radiological analyses were examined, sourced from electronic medical records.In accordance with the guidelines of the World Health Organization (WHO), the COVID-19 diagnoses of the participants were confirmed using Rt-PCR (12).Chest radiography was employed for the detection of inflammation, while radiological findings were utilized to differentiate pneumonia.Current guidelines on the severity of COVID-19 were consulted to make determinations.Participants were categorized into moderate and severe groups based on the assessment of disease severity (12).

Groups
The participants were grouped according to demographic characteristics, such as gender (female-male) and age categories (young-elderly or elderly-very elderly).Elderly status was determined in accordance with the criteria set forth by the WHO, with a threshold age of 74 years established.Two distinct groups were subsequently delineated: those aged up to 75 years and those aged 75 years and older.The severity of COVID-19 disease is divided into five groups in terms of clinical symptoms, laboratory and radiographic abnormalities, hemodynamics and organ functions.The severity of COVID-19 disease is divided into five groups in terms of clinical symptoms, laboratory and radiographic abnormalities, hemodynamics and organ functions.These are: • Asymptomatic or presymptomatic infection, • Mild, • Moderate, • Severe, • Critical illness (12).
In our study, participants in the symptomatic or presymptomatic infection, mild and moderate groups were combined to create the "moderate" group.Similarly, severe and critical groups are grouped together as "severe".

Measurements
Our research encompasses the analysis of hemogram

Ethics
The institution where the research was conducted has obtained ethical approval from the ethics committee.All procedures related to the research are in accordance with the Helsinki Declaration.

Statistical Analysis
In the analysis of our data, the software package SPSS 25.0 for Windows (SPSS Inc, Chicago, Illinois, USA) and Microsoft Excel (Microsoft Corporation, USA) were employed.The distribution of the data was assessed using the Kolmogorov-Smirnov test.Categorical variables were analyzed using the chi-squared test, and these variables were presented in both numerical and percentage formats.Parametric continuous variables were presented in terms of mean and standard deviation.Independent samples t-tests were employed to analyze these variables.

Results
In our study, there were 544 female and 406 male participants.Among the participants, 508 were aged 75 and above, while 442 participants were below 75 years of age, falling into the youngelderly category.Pneumonia was detected in 617 participants, with 254 of them classified as severe cases.Among the participants, 532 had chronic illnesses, and out of these, 231 were categorized as severe cases.The demographic characteristics of the participants, along with the presence of pneumonia and chronic illnesses, were compared in terms of the severity of COVID-19.Accordingly, statistically significant differences were found among groups in terms of gender, age, the presence of pneumonia, and the presence of chronic www.cmhrj.comillnesses (Table 1).Statistically, there is a significant difference between the groups in terms of neutrophil count.Other values are within normal limits in both groups, and there is no statistically significant difference between the groups in these parameters.Inflammatory markers are used to predict the severity of inflammatory events.Serious clinical manifestations occur through the production of proinflammatory cytokines, which contribute to the development of lymphopenia, neutrophilia and thrombocytopenia, as well as inflammatory markers such as CRP.High CRP levels are associated with the severity of COVID-19.In our study, ESR and CRP values were found to be statistically significantly higher in the severe group compared to the moderate group.Our results are consistent with previous work (23)(24)(25).
In previous studies, some hemogram-derived ratios such as neutrophil-to-lymphocyte ratio (18), lymphocyte-monocyte ratio (19) and platelet-to-lymphocyte ratio (20) were found to be significant in evaluating the severity of COVID-19.The hemogram-derived ratios included in the analysis in our study are LYM%, MON%, NEUT%, EOS%, and BAS%.Of these, the only one found to be significant is NEUT%.Studies on subject support the idea that neutrophils provide insight into the severity of CODID-19 (26,27).

Conclusion
The results obtained from our study showed that the percentages of "neutrophils among all WBC" parameter can be used as a potential marker in assessing the severity of COVID-19.In this way, a quick decision can be made about the severity of COVID-19.Hemogram-derived ratios are inexpensive parameters that can be easily calculated.Therefore, it would be beneficial to include them in common laboratory practices.

Table 1 . Comparison of Moderate and Severe COVID-19 Cases in Terms of Various Variables.
Moderate and severe cases of COVID-19 have been compared in terms of hemogram values.According to this comparison, the MCHC value is within normal limits in moderate cases, while in severe COVID-19 cases, it is lower than the normal range.aPTT values are found to be within normal limits in moderate cases, whereas in severe cases, they are elevated beyond the normal range.Both ESR and CRP are considerably elevated in both groups, with higher levels observed in the severe group compared to the moderate group.The differences between the groups are statistically significant in these parameters.A similar pattern is observed in the neutrophil count, where levels are above normal in both groups, with the severe group exhibiting higher levels than the moderate group.

Table 3 . Comparison of Moderate and Severe COVID-19 Cases in Terms of Hemogram-Derived Ratios.
(22)ived ratios were compared in moderate and severe Covid-19 cases.According to this analysis, the NEUT% value is above normal in both groups.It is higher in the severe group than in the moderate group.The statistical difference between the groups is significant.Other parameters are within detection of severe cases, and monitoring disease progression(3).Neutrophil-to-Lymphocyte Ratio, calculated as the ratio of absolute neutrophil count to absolute lymphocyte count, has emerged as a robust prognostic marker in COVID-19.This ratio is associated with an exaggerated inflammatory response and is indicative of poor outcomes.It can serve as an early warning sign for severe disease and guide therapeutic interventions(18).However, there are no proven data regarding the timing and selection of lung imaging.Bilateral multifocal alveolar opacities and pleural effusions are usually detected on chest x-ray.Radiological imaging is not a sensitive method for detecting this disease.Chest computed tomography is more sensitive than radiography but is not specific.No findings on radiographic imaging can completely rule out or rule out COVID-19 disease.The incidence of pneumonia increases with increasing disease severity(22).This explains why pneumonia is more common in severe cases.Likewise, age and chronic disease are also effective in making COVID-19 more severe.
Moderate and severe Covid-19 cases were compared in terms of hemogram values.ESR and CRP values are significantly higher in both groups.The differences between groups are statistically significant.The neutrophil count is above normal in both groups and there is a statistically significant difference between the groups.Other values are within normal limits in both groups.www.cmhrj.comHemogramparameters derived from complete blood count analysis, have emerged as valuable tools in the evaluation of COVID-19 patients.Hemogram-derived ratios, such as the neutrophil-tolymphocyte ratio, lymphocyte-to-monocyte ratio, platelet-tolymphocyte ratio, and others, serve as readily available, costeffective, and non-invasive markers that can aid in risk stratification, early COVID-19 is often detected as pneumonia.Chest x-ray, lung ultrasound and chest computed tomography are frequently used in diagnosis.