Evaluation of the factors predicting the need for intensive care of patients with COVID-19 aged above 65 years: data from an emergency department in Turkey

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INTRODUCTION
Coronavirus-19 (COVID- 19) disease is an infectious disease caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) 1,2 .Studies show that individuals aged ≥65 years are more susceptible to COVID-19 disease and have higher rates of hospital, intensive care, intubation, postintubation complications, and death [3][4][5][6] .Regarding the comorbid diseases, weak immune system also plays a role in increasing the sensitivity 7,8 .COVID-19, which develops with atypical symptoms, progresses to multiorgan failure within this age group 9 .It is noteworthy that admissions to the intensive care unit (ICU) are often the patients aged above 65 years 10 .A number of scoring systems have been developed to rapidly evaluate the patients with COVID-19 admitted to the emergency department.It has been stated that the National Early Warning Score (NEWS) in patients who are admitted to emergency department can reveal accurate results in both mortality within the hospital and hospitalization of patients from the emergency department to the ICU 11 .Quick Sequential Organ Failure Assessment (q-SOFA) is recommended as it provides a rapid prognosis to emergency department and critical care doctors and helps predict mortality 12 .The shock index (SI) can be used to predict mortality and the need for intensive care 13 .This study aims to determine the factors that predict the hospitalization of patients who aged above 65 years and diagnosed with COVID-19 in the emergency department and to evaluate those factors using the abovementioned scoring and indices.

Study design
The study was planned retrospectively and was started after the approval of the ethics committee (dated: February 5, 2021, No. 2021-01).The patients with a diagnosis of COVID-19 who were hospitalized to the emergency department of the university hospital between June 2020 and February 2021 were included in this study.Demographic findings, vital signs, serum biochemistry, hemogram, and blood gas values of the patients were analyzed.The NEWS, q-SOFA score, and SI were used to assess the severity of patient with COVID-19.The patients were divided into two groups, namely, patients who need intensive care and those who do not, according to the outcome of the emergency department.

Patients
The patients with positive polymerase chain reaction, aged above 65 years, and diagnosed with COVID-19 were included in this study.The patients aged above 65 years, trauma patients, the patients who were not diagnosed with COVID-19, and whose information could not be obtained from the system were excluded from the study.

Laboratory analysis
Serum biochemistry analyses were performed using colorimetric method in the 501 module of the Roche Cobas 6000 device, the hemogram analyses with the electrical impedance method in the Beckman Coulter DXH 800 device, and the blood gas values were examined using ISE (ion-selective electrode) potentiometric method in the radiometer ABL 800 device.

Statistical analysis
Mann-Whitney U test was used for numerical variables and chi-square test for comparison of categorical variables.
Logistic regression analysis was applied to predict ICU admission.A base model was created using the data with statistical significance in the multivariable analysis.The DeLong test was used for a pairwise comparison of the area under the curves 14 .SPSS version 26.0 was used for statistical analysis.

RESULTS
A total of 400 patients aged above 65 years and diagnosed with COVID-19 were included in the study.The mean age was 73 (interquartile range [IQR]: 68.0-80.75),and 229 (57.3%) patients were males.Demographic, laboratory parameters, and other characteristics of the patients are indicated in Table 1.
Comparing the groups with and without ICU hospitalization in terms of gender and the emergency department outcome, the NEWS was not significantly different between the two groups (p=0.630), while q-SOFA and SI were found to be significantly higher in the ICU group than the non-ICU groups (p<0.001), as given in Table 2.
The relationship between risk factors and mortality in patients with COVID-19 is given in Table 3.

DISCUSSION
In a study by Lee et al. 15 in patients aged above 65 years with a diagnosis of COVID-19, the median age was 72 and the majority were females 15 .Jin et al. 16 and Jansen et al. 17 showed that elderly males are more affected by COVID-19 infection than females.Elderly male gender is more prone to COVID-19 disease 18 .The mean age (73 years) and the predominance of male gender in our study correlate with the literature.The most common comorbid diseases in the elderly are hypertension (HT), cardiovascular diseases, diabetes mellitus (DM), chronic obstructive pulmonary disease, and hyperlipidemia 19 .In our study, HT and DM were found to be underlying comorbid diseases.Most common drugs related to these diseases used by the patients are antiplatelet and angiotensin-converting enzyme (ACE) inhibitors.HT is the most common comorbid disease diagnosed among the elderly patients.It was found that the use of drugs affecting the renin-angiotensinaldosterone (RAS) system, due to the ability of COVID-19 disease to enter the host cell by binding to ACE-2, increases the sensitivity to COVID-19 and causes viral replication 20,21 .In our study, the hospitalization rate of the patients aged above 65 years and diagnosed with COVID-19 was high.This finding is in line with many other studies in the literature [3][4][5][6] .Only 3.5% of the patients were discharged from the emergency department.It was found that the more severe the COVID-19, the higher is the mortality and the need for intensive care in the elderly patients 4 .In China and Italy, most mortality cases are with the patients aged above 60 years.Age plays a key role in the estimation of mortality 15,22 .It is suggested that old age is a risk factor for in-hospital deaths, is more sensitive to COVID-19 disease, and can have severe courses 9 .Comparing the 14-and 30-day mortality rates, this study found that mortality increases with an increase in the length of stay in the ICU.Studies also reveal that staying in the ICU with respiratory support for a long time increases mortality 20 .Ji et al. 23 stated that the number of ICU admissions were higher in the males aged above 65 years with an underlying comorbid disease 23 .In our study, there was no difference in terms of gender and the presence and number of comorbid diseases between patients who were admitted to the ICU and those who were not.
Vital signs play a key role in the early evaluation of patients diagnosed with COVID-19 and determination of whether the patients are at risk and require ICU admission 24 .In a study conducted on 2566 patients with an average age of 63, Hao et al. 25 found that there was no difference in respiratory rate, heart rate, and mean arterial pressure between the patients hospitalized in the ICU and those who were not 25 .In our study, systolic blood pressure, low oxygen saturation, and increased heart rate were found to be significant in terms of hospitalization in the ICU.Huang et al. 10 and Wang et al. 26 reported that dyspnea symptoms were more common in the patients admitted to ICU than in nonadmitted patients; the finding that is in line with our results.Liu et al. stated that in the patients aged above 60 years with COVID-19, the lymphocyte ratio was low and the C-reactive protein (CRP) level was high.Laboratory findings of elderly patients with COVID-19 also showed lymphopenia and high levels of CRP, lactate dehydrogenase (LDH),   and d-dimer 4,27,28 .In our study, unlike lymphopenia, base deficit and bicarbonate were found to be low.CRP, d-dimer, urea, and LDH levels were high, whereas lactate levels were high.These results were statistically significant, which are in line with the findings of the studies in the literature.
In the patients aged above 65 years with a diagnosis of COVID-19, the NEWS gave the most accurate score for both ICU admission and mortality estimation 29 .In our study, the NEWS was not significant for both groups.Due to the additional diseases of patients aged above 65 years and the reflection of these diseases on vital signs, it has been observed that it is as high in patients who are followed up in the service without the need for intensive care as in the patients in the ICU.In a retrospective study with patients with COVID-19, q-SOFA is recommended for the prediction of respiratory failure and mortality 30 .Doğanay et al. 13 stated that the SI is a useful parameter for mortality prevention, early intervention, and hospitalization of elderly patients and patients with COVID-19 with low oxygen saturation 13 .In our study, the use of q-SOFA in patients aged above 65 years with SI was found to be more effective in the prediction of admission to the ICU.

CONCLUSION
In age group of ³65 years, q-SOFA, SI, dyspnea, and urea elevation are effective in predicting the need for intensive care.

Table 3 .
Association between risk factors and mortality in the patients with COVID-19 and pairwise comparisons of receiver operating characteristic curves.