The importance of LDH/Albumin, LDH/Lymphocyte, and LDH/Platelet ratios in the evaluation of COVID-19 B.1.1.7 variant

Objectives: The aim is to investigate the usefulness of lactate dehydrogenase (LDH)/Albumin, LDH/Lymphocyte and LDH/Platelet ratios on the prognosis of coronavirus disease (COVID-19) Alpha (B.1.1.7) variant pneumonia. Methods: A total of 113 patients who were diagnosed with COVID-19 pneumonia and 60 healthy control group were included in this study. The cases were divided into 2 as classic COVID-19 group, and COVID-19 B.1.1.7 variant group. Complete blood count (CBC) and biochemical parameters of the patients were analyzed retrospectively. Patients with COVID-19 B.1.1.7 variant group were also grouped according to the length of stay in the hospital and the days of hospitalization. Results: LDH/Albumin, LDH/Platelet, and LDH/Lympho-cyte ratios were found to be higher in COVID-19 B.1.1.7 variant group when compared to the control group (p<0.001). The ferritin, neutrophils/lymphocyte (NLR) ratio, procalcitonin (PCT) and LDH/Albumin had the highest area under the curve (AUC) values in the COVID-19 B.1.1.7 variant group (0.950, 0.802, 0.759, and 0.742, respectively). Albumin, Lymphocytes and hemoglobin values were significantly higher in the COVID-19 B.1.1.7 variant group than in the classic COVID-19 group (p<0.05). Conclusions: LDH/Albumin and LDH/Lymphocyte ratios may be useful for clinicians in predicting the risk of progression to pneumonia in COVID-19 B.1.1.7 variant patients.

It was shown in many previous studies that COVID-19 and its variants cause high morbidity and mortality [7][8][9]. For this reason, it is important that healthcare services are provided regularly and adequately. In this respect, to make early clinical intervention and treatment possible, it is important to find reliable predictors for disease severity and mortality.
It has great importance to determine the predictor parameters for the infection in COVID-19 cases. The LDH, particularly high levels of LDH, were associated with worse outcomes in COVID-19 cases [7]. It was speculated that there are significant differences in LDH levels in COVID-19 cases. Low levels of albumin and lymphocyte are associated with morbidity and mortality in COVID-19 [8,10,11]. There is a need for parameters to help to understand the clinical progression of COVID-19 pneumonia and contribute to elucidating the pathophysiology of the disease. This study was planned based on the idea that LDH/Albumin, LDH/Lymphocyte, and LDH/Platelet ratios may be useful in evaluating the severity of the disease in patients with the COVID-19 B.1.1.7 variant.
The aim of this study was to make a comprehensive analysis of the clinical, laboratory and demographic characteristics of COVID-19 patients admitted to Ankara City Hospital and to compare their data with the classic COVID-19, COVID-19 B.1.1.7 variant and healthy control groups. In addition, the role of LDH/Albumin, LDH/ Lymphocyte, and LDH/Platelet ratios in the progression of patients in the COVID-19 B.1.1.7 variant group to COVID-19 pneumonia and in the pathogenesis of COVID-19 pneumonia was investigated.

Study design and participants
The present study was designed retrospectively and was approved by the Ethics Committee of Ankara City Hospital (E2-21-857). In the control group, patients who applied to Ankara City Hospital for routine control and had no known health problems were included. Between February and April 2021, patients with a diagnosis of classic COVID-19 and patients with a diagnosis of COVID-19 B.1.1.7 variant hospitalized in Ankara City Hospital's COVID-19 unit were included in the study group. The diagnostic criteria of the WHO temporary guideline were used in the study [1]. The demographic, clinical, laboratory data and radiological findings of the patients were obtained from electronic medical records and case record forms. The albumin, glucose, urea, creatinine, ferritin, ALT, AST, GGT, LDH, CRP, procalcitonin (PCT), D-dimer, troponin-I and CBC parameters of Group B.1.1.7 and the classic COVID-19 group were analyzed. CBC was analyzed using the ADVIA 2120 Hematology System (Siemens Healthcare Diagnostics, Erlangen, Germany). An Atellica Solution Immunoassay & Clinical Chemistry Analyzer (Siemens Healthcare Diagnostics, Erlangen, Germany) was used for measuring biochemical parameters. PT, APTT and D-dimer were measured using the Sysmex CS-5100 System (Siemens Healthcare Diagnostics, Erlangen, Germany). COVID-19 B.1.1.7 variant and classic COVID-19 groups were compared according to demographic data, radiological characteristics, laboratory findings, and clinical characteristics.

Diagnostic criteria
Oro/nasopharyngeal swab samples for RT-PCR, routine blood tests, and chest computed tomography (CT) were requested from the patients for the diagnosis of COVID-19. Those with a fever and respiratory symptoms, signs of pneumonia on CT, or clinical signs based on positive SARS-CoV-2 PCR results according to the WHO temporary guideline for the diagnosis of COVID-19 [1]. Those with positive B.1.1.7 variant analysis results for SARS-CoV-2 PCR were included in the study. Among the COVID-19 patients, the classic COVID-19 group was named Group N, and the COVID-19 B.1.1.7 variant group was named Group V.

Exclusion criteria
Patients who underwent mechanical ventilation, deceased patients, patients hospitalized in the intensive care unit (ICU), pregnant women and individuals younger than 18 years were not included in the study.

Statistical analysis
The Statistical Package for Social Sciences for Windows, Version 22 (IBM, Armonk, NY, USA) was used for the statistical analyses. The normality of variables was evaluated with the Kolmogorov-Smirnov test. Descriptive analysis was indicated using mean ± standard deviation (SD) for the parameters normally distributed, and median interquartile range, (IQR) was used for non-normally distributed variables. Normally distributed parameters were compared using one way ANOVA test. Non-normally distributed variables were compared with the Kruskal-Wallis test. Comparisons for categorical variables were performed using the Chi-square test or the Fisher's exact test. The receiver operation characteristic (ROC) curve was used to determine the efficacy of various parameters to predict the prognosis in the COVID-19 B.1.1.7 group. The optimal cut-off values of the PCT, ferritin, troponin-I, LDH, LDH/Albumin, LDH/Platelet, LDH/ Lymphocyte and NLR ratios were calculated by applying the ROC analysis. A value of p<0.05 was considered to be statistically significant.

Demographic, clinical, and treatment results
A total of 113 patients, 64 of whom were diagnosed with classic COVID-19 and 49 of whom were diagnosed with COVID-19 B.1.1.7 variant and 60 healthy subjects were included in the study. The median age of the COVID-19 B.1.1.7 group was found to be 48 (38.5-64.5), and that of the classic COVID-19 group was 73 (59-80), and 65 of the COVID-19 patients were male (p<0.001). Ground-glass opacity was found in the CT results of 44 patients in total, and ground-glass opacity was more dominant in the classic COVID-19 group (67.2%) than in the COVID-19 B.1.1.7 variant group (6.1%) (p<0.001). The median length of hospitalization was 10 days for both COVID-19 patient groups. The number of individuals who died was one and the patient who died was excluded from the study (Table 1).
The comorbidity was detected in 85 (75.2%) patients in total, and comorbidity was higher in patients in the classic COVID-19 group (p=0.015). The most common comorbidities were systemic hypertension (46, 30.9, 10.6, and 10.6%), diabetes, congestive heart disease, and ischemic heart disease, respectively. Favipiravir (n=69) was used predominantly in the treatment and steroid (n=29) was used secondarily. In B.1.1.7 group patients, steroid treatment was used in addition to the Favipiravir treatment ( Table 1).

Discussion
The COVID-19 pandemic still continues to affect the whole world with its variants and might cause an extensive clinical spectrum from subclinical disease to respiratory failure. LDH is an intracellular enzyme in cells of almost all organ systems. LDH values may increase due to decreased oxygenation as a result of multiple organ damage and upregulation of the glycolytic pathway [12]. In this study, when the COVID-19 B.1.1.7 variant group was compared with the healthy control group, it was shown that especially the LDH/Albumin, LDH/Lymphocyte and LDH/Platelet ratios were very useful in predicting the disease. These evaluated rates, as well as the age, presence of comorbidity, and symptoms at presentation may contribute to elucidating the pathogenesis of the disease in the COVID-19 B.1.1.7 variant group.
Due to the increase in lactate as a result of infection and tissue damage, the extracellular pH becomes acidic,  triggering the activation of metalloproteases and increasing macrophage-mediated angiogenesis [13]. Severe infections might cause cytokine-mediated tissue damage and LDH release. Elevated LDH can be expected in patients with severe COVID-19 infection because LDH is present in lung tissue [7]. In this study, when the COVID-19 B.1.1.7 variant group and the healthy control group were compared, it was found that the LDH, LDH/Albumin, LDH/Lymphocytes, and LDH/Platelet parameters were significant and higher than the control group (p<0.001).
The predictive value of LDH for severe COVID-19 patients was emphasized in some previous studies [14,15]. In this study, the optimal cut-off was found to be 293 U/L for LDH (sensitivity and specificity 78.1 and 57.1%, respectively), which is consistent with the study by Poggialia et al. [15]. Moreover, our study found that LDH/Albumin and LDH/Lymphocyte, parameters can be used as predictive diagnostic tools to identify subjects with the COVID-19   Since there is no definitive cure for COVID-19 yet and the importance of early isolation is indisputable, these rates can help clinicians with their ease of application and early diagnosis and mortality estimation.
We think that the high LDH/Albumin and LDH/ Lymphocyte ratios in the COVID-19 B.1.1.7 variant provide important information about the clinical course of the disease, as well as showing that there is recovery after treatment. These rates can give an idea for clinicians about the prognosis of the disease.
It was reported in various studies in the literature that serum albumin, lymphocytes, and platelet values were found to be low in COVID-19 patients [7,12,16,17]. Lymphopenia, elevated ferritin, procalcitonin and NLR were reported to be predictors of severe prognosis [18]. In our study, lymphopenia, high NLR, ferritin, procalcitonin levels were detected in both COVID-19 groups, which is consistent with the results of these studies [18,19]. Moreover, our study found that ferritin, NLR, and procalcitonin parameters can be used as predictive diagnostic tools to identify subjects with the COVID-19 B.  [12,19]. Although the NEU and CRP values were higher in the classic COVID-19 group in line with the meta-analysis when compared to the control group, they were found to be lower in the COVID-19 B.1.1.7 variant group [12]. In their meta-analysis, Ji et al. reported that inflammatory markers increased according to the severity of COVID-19. In this study, inflammatory markers WBC, CRP and PCT were found to be lower in the COVID-19 B.1.1.7 variant group compared to the classical COVID-19 group. Therefore, this study suggests that the prognosis of the COVID-19 B.1.1.7 variant is milder than that of the classic COVID-19 group, similar to the results of the meta-analysis by Ji et al. [20].
In the present study, the most commonly used drug was found to be Favipiravir in the treatment of COVID-19 patients. Hydroxychloroquine was used in limited cases. Although their use was controversial at the beginning of the pandemic, these drugs were used widely for treatment as the experience was gained in time, and were added to the treatment with steroids in some patients within the indication.
When the comorbid disease states of COVID-19 cases were examined in this study, the most common comorbid diseases were found to be systemic hypertension, Diabetes mellitus, congestive heart disease, ischemic heart disease, chronic renal disease, cancer, cerebrovascular events, and chronic obstructive pulmonary disease [1,[21][22][23][24][25]. Fever, cough, shortness of breath, and fatigue were the most common symptoms in the symptomatology. One of the hospitalized cases died of all these additional diseases and symptoms. One case that was recorded was an intubated patient who had bilateral lung involvement and died as a result of cardiac ischemia and respiratory failure with ischemic heart disease comorbidity. The limitation of this study was the small sampling size. We included all COVID-19 patients who met the diagnostic criteria and were hospitalized due to the variant. Could the COVID-19 B.1.1.7 variant group accompany by undiagnosed diseases cause the deterioration of pneumonia? Does it play a role in the pathogenesis of the disease? Comprehensive studies may be necessary in this regard.