Pattern of cytopenias and systemic immune-inflammation index among hospitalised patients of COVID-19

Objective: To compare the extent of cytopenias and systemic immune inflammation index of hospitalised coronavirus disease-2019 patients during the first and second/third waves of the pandemic. Method: The retrospective, cross-sectional study was conducted in October 2021 at Fatima Memorial Hospital, Lahore, Pakistan, and comprised data of hospitalised coronavirus disease-2019 patients regardless of age and gender from May 2020 to June 2021. Data was segregated into first wave that lasted from May to July 2020, second wave that lasted from early November to mid-December 2020, and third wave that ranged from mid-March to June 2021. For comparison purposes, the data of first wave was in group A, while data of second and third waves was pooled into group B. Age, gender, comorbidities, requirement of ventilator support and outcome of the patients was noted. Inflammatory markers were compared on the basis of complete blood count and systemic immune-inflammation index data. Data was analysed using SPSS 25. Results: Of the 202 patients, 90(44.5%) were in group A and 112(55.4%) were in group B. There were 108(53.5%) males and 94(46.5%) females. The median age in males was 58 years (interquartile range: 21 years) and it was 56 years (interquartile range: 21 years) in females. Neutrophilia ( p <0.001), leukocytosis ( p <0.001) and lymphocytopenia ( p <0.001) had direct association with increased systemic immune-inflammation. Raised systemic immune-inflammation also had an association with increased requirement of ventilator support (p=0.2) and increased mortality ( p =0.001). There were more females, more critical patients, more patients with anaemia, leukopenia, lymphocytopenia and thrombocytopenia in group B compared to group A ( p <0.05). Need for ventilator support and mortality were also higher in group B compared to group A ( p <0.05). Conclusion: All the indicators analysed were worse during the second and third waves of coronavirus disease-2019 compared to the first wave of the pandemic.


Introduction
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the global pandemic of coronavirus disease-2019 (COVID-19) which resulted in considerable morbidity and mortality across the world. 1 As per the World Health Organisation (WHO) data, there were over 500 million confirmed cases and over 6 million deaths reported worldwide. 2VID-19 is highly communicable and contagious disease and can lead to diversity of symptoms, including mild fever, dry cough, myalgia and headache as well as gastrointestinal symptoms, including abdominal pain, diarrhoea and vomiting, and respiratory symptoms leading to a critical stage needing expert management at intensive care units (ICUs). 3Hospitalisation of patients was seen with worsening clinical symptoms, like life-threatening respiratory failure with pulmonary decline.This usually happens when a high level of pro-inflammatory cytokines are released which lead to tissue damage. 4lationship of COVID-19 with laboratory parameters have been well-established by many studies. 5,6Respiratory system is the main system involved in COVID-19, but multisystemic involvement was also seen, like the haemopoietic system in which blood count anomalies, like neutrophilia and lymphopenia, were particularly seen in COVID-19 patients which also had a prognostic significance. 7gher values of neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR) and platelets-tolymphocytes ratio (PLR) can be useful predictive inflammatory markers for the disease course, and their increased levels were directly proportional to disease severity and poor outcome in COVID-19 patients.Systemic immune-inflammatory index (SII) has served as an expedient, affordable and noninvasive prognostic marker for patients of solid malignancy and carcinomas. 8,9attern of cytopenias & systemic immune-inflammation index among hospitalized …….
Moreover, SII also has positive prognostic value in COVID-19 patients and help in assessing the length of hospital stay (LOS) and predicts the mortality in these patients. 10kistan had its first confirmed case of COVID-19 in February 2020 and the first wave lasted till July 2020.The second wave lasted from November to December 2020 and the third wave from mid-March to June 2021.The fourth wave, which was presumed to be caused by the delta variant of SARS-CoV-2, lasted from July to September 2021.As per data till April 20, 2022, there were over 1.5 million confirmed COVID-19 cases and over 30,000 deaths reported in Pakistan. 11e current study was planned to compare the extent of cytopenias and SII of hospitalised COVID-19 patients during the first and second/third waves of the pandemic in a Pakistani setting.

Materials and Methods
The retrospective, cross-sectional study was conducted in October 2021 at the Department of Pathology in collaboration with the Department of Medicine, Fatima Memorial Hospital, Lahore, Pakistan, and comprised data of hospitalised COVID-19 patients regardless of age and gender from May 2020 to June 2021.Data was segregated into first wave that lasted from May to July 2020, second wave that lasted from early November to mid-December 2020, and third wave that ranged from mid-March to June 2021.For comparison purposes, the data of first wave was in group A, while data of second and third waves was pooled together into group B. The data was retrieved using consecutive nonprobability sampling technique after approval from Fatima Memorial college of medicine and dentistry institutional ethics review board (FMH-08-2021-IRB934-M).The study was in line with the Strengthening the Reporting of Cohort Studies in Surgery (STROCSS) criteria. 12ing a country with low socioeconomic status with resource limitations, gene sequencing was notperformed to detect the type of different variants of the virus.Diagnosis of COVID-19 had been confirmed on the basis of positive polymerase chain reaction (PCR) finding on nasal swab.Data of patients with chronic liver disease (CLD) and known haematological disorders was excluded.
Data retrieved included age, gender, comorbidities, requirement of ventilator support and outcome of the patients.Inflammatory markers were calculated from complete blood count (CBC) values.SII, which is an indicator related to inflammation that can mirror the immune and inflammation state of a patient 10, was calculated on the basis of absolute platelet count(APC), absolute neutrophil count (ANC) and absolute lymphocyte count (ALC) (APC x ANC / ALC), and SII >600 was labelled as raised and a bad prognostic marker. 13For the purpose of the current study, patients with SII <600 were placed in group I, and patients with SII >600 in group II.CBC was performed on Sysmex XN-10 USA, (Five part haematology analyzer).Reference cut-off values to label cytopenia were taken from WHO and literaure. 14,15NLR was calculated, and value >3 was considered raised.PLR was calculated as APC / ALC, and raised PLR was taken as >149 for males and >172 for females. 16MLR was also calculated as absolute monocyte count (AMC) / ALC, and 0.23 was considered the cut-off level. 17Patients with oxygen saturation (SaO2) <94% and >50% lung involvement were considered to have severe disease, and patients requiring either invasive or non-invasive ventilator support with other complications were labelled as critical disease. 18ta was analysed using SPSS 25.Data was stratified according to age, gender, SII and different waves of COVID-19.Categorical variables were expressed as frequencies and percentages, while quantitative variables were expressed as median with interquartile range (IQR).Continuous variables were analysed using Mann-Whitney U test, while categorical variables were analysed using Chisquare and Fischer exact tests.NLR, PLR, MLR and SII were derived from the same CBC parameters, so no statistical comparison was done between SII and these inflammatory markers.P<0.05 was considered significant.

Discussion
The clinical spectrum of coronavirus ranges from asymptomatic or mild disease to fatal and life-threatening illness.Laboratory findings responsible for worst outcome include lymphopenia, thrombocytopenia, elevated liver enzyme, lactate dehydrogenase (LDH), inflammatory markers, D-Dimers, prothrombin time, troponin, creatinine phosphokinase and acute kidney injury.Due to high infectivity and mortality rates of COVID-19, early diagnosis of the disease is essential. 19Results of the current study showed that co-morbidities and deranged haematological parameters had direct impact on the severity and outcome of the disease in COVID-19 patients.The study reported higher percentage of infectivity in males during the first wave, while during the second/third wave phase, infectivity was more prevalent in females.A study also showed higher prevalence of female hospitalisation than males during the second wave. 20Among co-morbidities, Hypertension was the most prevalent, followed by DM, IHD, CKD, asthma, COPD and malignancy.A study also concluded that HTN, DM and cardiovascular diseases (CVDs) were the most frequent co-morbidities among COVID-19 patients. 21It was observed in the current study that mortality was higher in patients who had comorbidities.Higher number of mortalities in patients with co-morbidities was also reported earlier. 22A meta-analysis illustrated that higher mortality was seen in patients with co-morbidities, like HTB, DM and respiratory diseases. 23I is used for risk stratification of patients and has an important role in prognosticating the outcomes related to COVID-19. 24In the current study, patients with high SII (≥600) showed higher mortality and required increased ventilator support.Hong Li et al. reported the same findings. 25Infectious diseases cause inflammation which has a significant role in the progression of viral pneumonia, including COVID-19.There is an immune response imbalance due to weak adaptive immune response seen in severe inflammation.Circulating biomarkers, like NLR, PLR and MLR, in COVID-19 represented inflammation and immune status as predictors of prognosis.Elevated NLR was associated with poor prognosis and severe disease in COVID-19.NLR was seen elevated in patients with raised SII.Yang AP et al. found a positive association of elevated NLR with severity of disease and poor prognosis.Similarly, elevated PLR value suggested an overactive inflammatory response and was associated with severe disease and poor prognosis. 26In the current study, PLR was found elevated in patients with high SII and had statistical significance.Simadibrata et al. suggested that elevated PLR in COVID-19 patients could reflect cytokine storm. 27In the current study, raised SII showed a direct association with increased mortality.Fois AG et al. also reported significantly higher value, among other markers, of SII in non-survivors compared to survivors. 28High SII was also directly associated with the requirement of invasive and noninvasive ventilator support in the current study, and the same was concluded by a study that had 326 COVID-19 patients. 25ta of comparative studies on haematological parameters between first and subsequent waves is limited.The current  study concluded that lymphocytopenia and thrombocytopenia were more prevalent during the phase of second/third waves.The findings of the current study concurred with the study conducted on Romanian patients which found prevalence of lymphopenia and thrombocytopenia during the second wave. 29Rahim S et al. also found lymphopenia as a prominent finding during the second wave. 30Anaemia was found to be more prevalent during the second/third waves in the current study, but it was not significant statistically and was corrected by blood transfusion.
In the current study, leukopenia was also observed during the second/third waves of COVID-19.Li YX et al. concluded that leukopenia, lymphocytopenia and eosinophil cytopenia were more prominent findings in COVID-19 patients than non-COVID-19 patients. 31ility of other inflammatory markers, like NLR, PLR, MLR and SII, have established a positive role in predicting the severity and course of disease along with directing the management plans for the COVID-19 patients as well as prognosis. 32These inflammatory markers showed a strong association with disease course, severity and outcome of COVID-19 disease, but no significant difference was found between the different waves of COVID-19 in the current study.Increased invasive and non-invasive ventilatory support requirement and an increased number of critical patients were observed during the second/third wave of COVID-19 in comparison with the first wave.
More mortalities were noted in the current study during the second/third waves of COVID-19.The same results were concluded by Kumar G et al. in India, where mortality increased by 3.1% during the second wave of COVID-19. 33ncreased in-hospital deaths were also observed by Jassat W et al. during the second wave in South Africa. 34However, the findings differed from a study which concluded that fewer deaths occurred during the second wave compared to the first wave of COVID-19. 35e current study has limitations.It was unable to detect the different variants and mutations of coronavirus that were detected worldwide.As such, it was impossible to categorise the haematological parameters according to specific variants of COVID-19.
Although this was a single-centre study, the results can be applicable to COVID-19 patients of other ethnic origins.

Conclusion
SII was found to be a good, expedient and non-invasive predicting tool in COVID -19 prognosis.It was directly associated with cytopenias, severity of disease, ICU admissions, ventilator support as well as outcome of the disease.SII can be used as a useful inflammatory marker for COVID-19 prognosis.
27.8%), but it was not statistically significant (p=0.09).Raised ANC, NLR, MLR, PLR and SII values were directly associated with severity of COVID-19 infection and these inflammatory markers showed no significant intergroup variations (Table).High-resolution computed tomography (HRCT) score was only available for group B, which was 15 (IQR: 8).No patient with HRCT <8 or between 8-15 needed ventilator support.There were 58(51.7%)patients with HRCT >15, and 22(37.9%) of them required ventilator support.Ventilator support was needed in 7(7.8%) group A patients and 22(19.6%) group B patients (p=0.002).Prevalence of mortalities was significantly high in group B compared to group A (p<0.001).

Table :
Median (IQR) values of haematological parameters and their comparison between the first and second/third waves of COVID-19.