key: cord-0781403-w68owgss
authors: Asghar, Muhammad Sohaib; Khan, Noman Ahmed; Haider Kazmi, Syed Jawad; Ahmed, Aftab; Hassan, Maira; Jawed, Rumael; Akram, Mohammed; Rasheed, Uzma; Memon, Gul Muhammad; Ahmed, Muhammad Umer; Tahniyat, Umme; Tirmizi, Syeda Batool
title: Hematological parameters predicting severity and mortality in COVID-19 patients of Pakistan: a retrospective comparative analysis
date: 2020-10-29
journal: Journal of community hospital internal medicine perspectives
DOI: 10.1080/20009666.2020.1816276
sha: ac9d16963850b21485099dffadd875605705a598
doc_id: 781403
cord_uid: w68owgss

Background and Objectives: COVID-19 is a global pandemic. In our study, we aimed to utilize the hematological parameters in predicting the prognosis and mortality in COVID-19 patients. Materials and methods: A retrospective, observational study was conducted to include all the admitted patients (n = 191) having COVID-19 Polymerase chain reaction (PCR) positive, and evaluated those for prognosis and disease outcome by utilizing several biochemical and hematological markers. Results: Amongst the patients admitted in the ward versus in the intensive care unit (ICU), there were significant differences in mean hemoglobin (P = 0.003), total leukocyte count (P = 0.001), absolute neutrophil and lymphocyte counts (P < 0.001), absolute monocyte count (P = 0.019), Neutrophil-to-Lymphocyte ratio (NLR) and Lymphocyte-to-Monocyte ratio (LMR) (P < 0.001), Platelet-to-Lymphocyte ratio (PLR) and Lymphocyte-to C-reactive protein ratio (LCR) (P = 0.002), and C-reactive protein (CRP) levels (P < 0.001). Amongst the deceased patients, there was significant leukocytosis (P = 0.008), neutrophilia and lymphopenia (P < 0.001), increased NLR (P = 0.001), decreased LMR (P < 0.001), increased PLR (p = 0.017), decreased LCR (p = 0.003), and elevated CRP level (P < 0.001). A receiver operating characteristic curve obtained for the above parameters showed NLR (AUC: 0.841, PPV: 83.6%) and PLR (AUC: 0.703, PPV: 81.8%) for ICU patients, while NLR (AUC: 0.860, PPV: 91.1%) and PLR (AUC: 0.677, PPV: 87.5%) for the deceased patients had significant accuracy for predicting the disease severity of COVID-19 in comparison to survivors. Conclusion: The inflammatory markers and hematological indices are a good guide for predicting the severity and disease outcome of coronavirus disease. NLR and PLR are elevated in severe disease while LMR and LCR are inversely correlating with disease severity.

COVID-19 is a global pandemic, also affecting Pakistan with 287,300 cases, and 6153 deaths as of 14 August 2020. Many hematological parameters are currently been utilized to predict outcomes and mortality in patients infected with SARS CoV-2. The neutrophil to lymphocyte ratio (NLR), is an inflammatory mediator used as predictor of systemic inflammation [1] . Numerous studies conducted around globe have reported about neutrophil to lymphocyte ratio (NLR) as a predictor of prognosis in a variety of cancers (breast, ovary, lung), cardiovascular disorders (coronary procedures and coronary artery bypass grafting), infectious disorders (community-acquired pneumonia, corona) and sepsis in general [1] [2] [3] [4] [5] .

Neutrophil to lymphocyte ratio (NLR) is promptly accessible parameter calibrated entirely through a report of complete blood count (CBC); it is economical and simple as compared to the rest of mediators making it potential diagnostic criterion [2] [3] [4] . Neutrophil to lymphocyte ratio (NLR) is a prominent predictor of severity of disease, if high levels are detected it determines poor prognosis and high mortality within patients of intensive care units [3] [4] [5] . Elevating levels of neutrophil to lymphocyte ratio (NLR) projects towards the prediction of mortality among sufferers of acute coronary syndrome, intracerebral hemorrhage, polymyositis, dermatomyositis, and cancers [6, 7] . Inflammatory states of the body triggers excessive yield of neutrophils and simultaneously bringing about apoptosis of lymphocytes thus proceeding towards immunological aberration in body and potentiating severity of disorder and chances of death [6] . Elevated levels of neutrophil to lymphocyte ratio (NLR) have genetic predilection directed towards males as compared to females in terms of severity of disease [8] . Age of sufferer also plays a vital role in outcomes of neutrophil to lymphocyte ratio (NLR) as this ratio is elevated among the elder population (50->70 years) as compared to sufferers of younger age group [4] . Racial differences are also reported to be encountered in outcomes of neutrophil to lymphocyte ratio as the values are elevated highly among western populations in comparison with the African and Asian populations [9] .

The platelet to lymphocyte ratio (PLR) is also an effective inflammatory mediator utilized in predicting the prognosis of many disorders and mortality among patients [4, 10, 11] . Platelet to lymphocyte ratio (PLR) is an indicator of prognosis in cardiovascular diseases, rheumatic disorders, infectious diseases, and organ injuring disorders such as systemic erythematous lupus (SLE) and malignancies [10, 12] Platelets have dual properties involving both hemostasis and immunity [13, 14] . This ratio is easily accessible and is calibrated by a complete blood count (CBC) test [15] . The platelet to lymphocyte ratio is also dependent upon age and gender, with women detected with elevated PLR at the age of 30-59 and decreased levels at the age of 50 as compared to males [15] . Elevated levels of platelet to lymphocyte ratio (PLR) are associated with increased severity and high mortality [15] .

The monocyte to lymphocyte ratio (LMR), is also an immune mediator in line with NLR and PLR [16] . The high count of monocytes and low count of lymphocytes are suggestive of increased incidence of mortality and decline of prognosis among patients with severe disease [17] . The monocyte to lymphocyte ratio is an indicator of the prognosis of cardiovascular diseases, a variety of malignancies, autoimmune diseases, and chronic infections like tuberculosis [18] .

The lymphocyte to the C-reactive protein ratio (LCR) is another marker linked with severity of the disease [7] . LCR is utilized as a systemic inflammatory mediator predicting the mortality and prognosis in patients with malignancies like colorectal and gastric carcinoma [19] . Sufferers of malignancies with low pre-operative LCR reported to have declined in prognosis as compared to patients with high pre-operative LCR [19] . In our study, we aimed to utilize all these hematological and biochemical parameters in predicting the prognosis and mortality in patients of COVID-19. The study focused on all the hospital admissions, severity of disease with length of hospital stay, and the correlation amongst them.

The study was conducted as a single centered, retrospective, observational study, started from 27 February till 30 June 2020, and including all patients who were diagnosed as COVID-19 positive via Polymerase Chain Reaction (PCR). The outcomes of the disease were followed along with the hospital course at the time of analysis. Out of the total 191 patients admitted, 106 were recovered and discharged with negative PCR for COVID-19, 41 patients who remain asymptomatic were discharged for home isolation without PCR being negative. A total of 44 deaths occurred due to COVID-19, out of whom 19 patients were admitted to ICU for critical care management and ventilators.

The following hematological parameters were used to determine the severity of the disease and predicting the outcomes:

It was first created and used by Sato, et al. in the chemotherapeutic response of esophageal carcinoma in 2012 [20] . We calculated NLR by dividing the relative percentage of neutrophils by lymphocytes. Normally, it should be below 3, but a ratio of above 3 signifies acute stress, and a ratio of more than 9 signifies sepsis. But variability occurs in populations regarding the cut-off value of NLR with some studies suggesting a cut-off value of 4 [1].

It was calculated by dividing absolute lymphocyte count (x10 3 cells/uL) with absolute monocyte count (x10 3 cells/uL) [17] . The normal range is 3-9 with variability amongst populations [4] .

It was calculated by dividing absolute platelet counts (x10 3 cells/uL) with absolute lymphocyte count (x10 3 cells/uL), which usually lies in between 50 and 150 but subjected to variability amongst populations [4] .

This marker was calculated by dividing the absolute lymphocyte count (number/uL) with CRP levels (mg/ dl) [19] . The usual values of CRP were calculated in our laboratory as g/dL; hence, it was converted into mg/dl and lymphocytes (x10 3 cells/uL) were also converted into absolute counts (number/uL) before calculating this ratio.

The statistical analysis was conducted by the Statistical Package for the Social Sciences (SPSS version 25.0). All continuous variables were described as both mean & standard deviation as well as median & interquartile range. The means were then compared using both independent sample t-test and Mann-Whitney U-test, and amongst them, the p-value was considered more significant according to Levene statistics. The comparison of categorical data was done either using the Chi-square test or Fisher's exact test according to the limitation of data. In a paired sample t-test, each subject or entity was measured twice, resulting in pairs of observations (such as the progress of labs before and after treatment). A p-value of <0.05 was considered statistically significant. All the highly significant values were rounded off as <0.001.

The mean age of the study population was 52.65 ± 16.13 with females slightly younger than males (P = 0.232). The most common age group has been 50-75 years with two-thirds of them being males (P = 0.469). The majority of the patients were having mild to moderate symptoms hence admitted in isolation ward (68.07%), while rest 31.93% having a severe disease were admitted in the Intensive care unit (ICU). The length of the hospital was significantly more in ICU patients (P = 0.001) as shown in Table 1 . The descriptive statistics of admitting laboratory investigations are given in Table 2 .

Amongst the patients admitted in the ward vs in ICU, there were significant differences in mean hemoglobin (P = 0.003), total leukocyte count (P = 0.001), absolute neutrophil and lymphocyte counts (P < 0.001), absolute monocyte count (P = 0.019), NLR and LMR (P < 0.001), PLR and LCR (P = 0.002), as shown in Table 3 . Amongst the deceased patients, there was significant leukocytosis (P < 0.008), neutrophilia and lymphopenia (P < 0.001), increased NLR (P = 0.001), decreased LMR (P < 0.001), increased PLR (P = 0.017), and decreased LCR (P = 0.003), as shown in Table 4 .

A receiver operating characteristic (ROC) curve obtained for the above parameters showed NLR (AUC: 0.841, PPV: 83.6%) and PLR (AUC: 0.703, PPV: 81.8%) for ICU patients, while NLR (AUC: 0.860, PPV: 91.1%) and PLR (AUC: 0.677, PPV: 87.5%) for the deceased patients had significant accuracy in predicting the disease severity of COVID-19 as shown in Table 2 as well as Figures 1 and 2 . LMR and LCR were found inversely related to the severity of the disease.

In this study majority of individuals included in our study population reported ages above 50 years with a study population of 54 individuals comprising a majority of males. In our study, we detected elevated counts of neutrophils (neutrophilia) but in contrast, low lymphocyte counts (lymphopenia) thus resulting in an elevated ratio of neutrophil-tolymphocyte ratio in critically ill suffering for coronavirus disease 19 (COVID-19) coinciding with outcomes of several studies [6] [7] [8] 11, [21] [22] [23] [24] [25] . In our study, we also detected significantly high counts of neutrophils and lowest counts of lymphocytes along with prominent elevation of neutrophil-tolymphocyte ratios among patients with refractory disease admitted to intensive care units and deceased patients when compared with patients in isolation wards and at initial phases of disease synchronizing with detections of numerous studies [6] [7] [8] [21] [22] [23] [24] [25] . Total leukocyte count (TLC) was significantly elevated in patients who are critically infected or deceased in comparison with patients in isolation wards or recovered correlating with findings of countable studies [6] [7] [8] [21] [22] [23] [24] [25] . Prominently elevated levels of neutrophil-to-lymphocyte ratio in deceased patients were detected in our study rendering NLR as a predictor of mortality thus independent parameter for prognosis among sufferers of coronavirus disease (COVID-19) this outcome detected in our study coincides with results and findings of several studies [6] [7] [8] [21] [22] [23] [24] [25] . In our study median of patients residing within isolation wards and median of patients under critical condition is in similar accord in comparison with a study conducted in similar patterns thus coinciding with our findings [6, 7, 11, [21] [22] [23] [24] [25] .

In our study, elevated count of platelets (thrombocytosis) was detected in patients of coronavirus disease (COVID-19) at time of initial phase of infection (admission) and critical phase of infection (intensive care unit) and death as compared with patients in isolation wards or recovered synchronizing with outcomes of countable studies [11] . In contrast, a decline in counts of lymphocytes (lymphocytopenia) was detected in patients of critical phase thus resulting in predominant high levels of platelet-to-lymphocyte ratio among sufferers under treatment in intensive care units or deceased as compared with sufferers in their initial phase of infection (admission) or residing in isolation wards thus proving platelet-tolymphocyte ratio as one of independent mediator predicting prognosis and mortality in critically ill sufferers correlating with the outcome of another study [11] . The means of platelet-to-lymphocyte ratio detected among patients under treatment in the isolation ward and intensive care units coincide with the means of the study mentioned above [11] .

In our study, elevated counts of monocytes and decreased counts of lymphocyte (lymphocytopenia) were detected among patients under treatment in intensive care units or deceased as compared with patients admitted at recent intervals or in isolation wards coinciding with findings of negligible study [26] . Increased monocytes and decreased lymphocytes result in decreased lymphocyte-to-monocyte ratio among patients of ICU or deceased thus rendering declined ratio of lymphocyte-to-monocyte as an indicator of poor prognosis and increased chances of mortality among patients suffering from coronavirus disease correlating with few studies [26] . The mean value of the lymphocyte-to-monocyte ratio coincides with the mean of another study calculating LMR in coronavirus disease patients [26] .

Elevated levels of C-reactive protein and decrease in lymphocyte count (lymphocytopenia) were observed within outcomes of study resulting in declined lymphocyte-to-C reactive protein ratio (LCR) within patients critically ill or deceased as compared to outcomes of patients in isolation wards or recovered coinciding with results of a countable study [7] . A decrease in the lymphocyte-to-C reactive protein ratio is suggestive of poor prognosis and potential mortality among sufferers of coronavirus disease (COVID-19) [7] .

The inflammatory markers and hematological parameters are a good guide for predicting the severity and disease outcome, but the in-hospital management causing changes to these parameters are not predictory to overall mortality or therapeutic benefits, hence these parameters are limited for initial survey only till further extensive studies take place on follow-up laboratory investigations. The hematological markers known to be elevated in the current pandemic were NLR and PLR, but LMR and LCR were considered to be of a lesser concern, however, they are directly correlating with disease severity in our study. NLR and PLR are more likely to be elevated in severe disease as well as LMR and LCR are inversely correlating with disease severity and mortalities.

The authors declare no conflicts of interest with this article's content.

This work is not supported by any sponsors. No funding required in this study. 

Ethical approval was taken in this study from the institutional review board and consent to participate has been taken from all the patient's guardians with informed written consent. 

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