Hospitalization of elderly people due to COVID-19 in the State of Paraná, Brazil: analysis of associated factors

Objective: To analyze the prevalence and factors associated with hospitalization of elderly people with COVID-19 in the State of Paraná, PR, Brazil. Methods: A cross-sectional study linked to the cohort “Longitudinal Monitoring of adults and elderly people who were discharged from hospital admission due to COVID-19”, was carried out using information contained in the compulsory notification forms of the Notifiable Diseases Information System. Analyzes were carried out using relative and absolute frequencies, applying the chi-square test adopted in


Introduction
In December 2019, a set of types of pneumonia caused by a virus known as the new coronavirus, which came to be called SARS-CoV-2, was reported in China.In March 2020, it reached pandemic proportions due to the large number of cases in several countries. (1)Until October 2022, Brazil recorded more than 4.6 million cases and 687,144 deaths from the disease. (2)he acute respiratory syndrome caused by COVID-19 spread rapidly, mainly affecting the respiratory tract, leading infected individuals to develop symptoms such as fever, dyspnea, cough, and loss of smell and taste.In some cases, involvement of the gastrointestinal system occurred. (1)ny individual can be infected by SARS-CoV-2 regardless of age group and other factors, but elderly people present greater complications.The presence of underlying diseases and deficits in the physical, sensory, and cognitive functions of the elderly, implies restrictions in their daily activities, making them dependent in their respective areas, resulting in the need for caregivers and implying classifying them as a group of higher risk. (3)n the elderly population, who already have some underlying chronic condition, such as hypertension, diabetes mellitus, chronic obstructive pulmonary disease, and other cardiovascular diseases, serious health complications were observed and many of these individuals died.In these cases, the disease manifests more aggressively: the symptoms presented, such as dyspnea, dry cough, and runny nose, are generally focused on the upper airways, and headache and fever may also occur.In general, its onset requires hospitalization, which can lead to death due to complications. (4,5)n addition to underlying diseases being a greater risk factor for worsening COVID-19, studies have shown that sociodemographic factors such as male sex (in addition to advanced age) also contribute to possible complications.Survival in countries with low development, where the majority of the population is elderly, people already have some comorbidity. (6)he studies that identified the causes involved in the development of the severe form of COVID-19 allowed for filling the knowledge gaps that still exist and implementing specific health actions to reduce and control the disease, directly impacting the severity of cases and hospital admission and mortality rates.
Thus, the present study intended to contribute to the advancement of knowledge based on evidence and prevent the development of the severe form of the disease, which would make it possible to reduce the number of hospitalizations and deaths and thus the costs to the health system.Therefore, the objective of this study was to analyze the prevalence and factors associated with the hospitalization of elderly people with COVID-19 in the State of Paraná, PR, Brazil.

Methods
This population-based cross-sectional study, nested to the cohort "Longitudinal Follow-up of adults and elderly who were discharged from hospitalization due to COVID-19", was carried out in cooperation between the Universidade Estadual de Maringá (UEM) and the Health Secretariat of the State of Paraná with financial support from the National Council for Scientific and Technological Development (CNPQ).
The study was conducted in the State of Paraná (southern region of Brazil), with a total area of 199,298,981 km 2 .It has 399 municipalities, divided into four health macro-regions, which are subdivided into 22 Regional Health Sections. (7)he State of Paraná has a population of 11,675,661 inhabitants (2022 estimate), maintaining the ranking as the most populous state in the southern region of Brazil.The different age groups were estimated to reach around 1.9 million (over 60 years old), 1.1 million (60-69 years old; prevalent), just over 0.5 million (70-79 years old), and around 265 thousand inhabitants (80 years or more). (8)he study population included people aged 60 years or older living in Paraná, who were hospitalized for COVID-19 in the period from March 2020 to September 2021.
As eligibility criteria, people residing in Paraná with an age equal to or older than 60 years, such as confirmed cases of Severe Acute Respiratory Syndrome (SARS) associated with Coronavirus and people hospitalized in the ward or ICU who were discharged in the period from March 2020 to September 2021 were included according to the SARS notification forms.Case notifications of elderly people hospitalized in Paraná, but living in other states, were excluded from the analysis.
The population sampling was composed based on the compulsory notification forms of SARS associated with Coronavirus that are part of the Influenza Epidemiological Surveillance Information System (SIVEP/IESIS-Influenza), in databases made available by the Ministry of Health (MH) (8) and updated on November 8, 2021.
The dependent variables used in this study consist of the effect, illness, or injury observed by individuals during the study, who underwent hospitalization in the ward and/or ICU due to the worsening of COVID-19.
The independent or predictive variables were subdivided into Sociodemographic Data: age (≥60 years), sex (male or female), race or skin color (white, black, yellow, brown, or indigenous), education [no education or illiterate, primary (1 st Cycle), primary (2 nd cycle), secondary, higher education, and not applicable], zone (urban, rural, or peri-urban), regional health department corresponding to the location of residence (according to the MH definitions), and resides in the municipality of hospitalization (yes or no).
Vaccination History of the Elderly: Referring to elderly data on the use of antiviral medication against influenza (yes or no), and whether he/she received flu vaccine in the last campaign (yes or no).Clinical Data consisted of the following: Do you have a risk factor or comorbidity (yes or no)?Among the risk factors cited are as follows: Diabetes mellitus, immunodeficiency or immunosuppression, asthma, and obesity, including chronic diseases (cardiovascular, hepatic, neurological, renal, hematological, and pneumopathy).In addition, the existence of signs and symptoms (yes or no) such as fever, cough, sore throat, dyspnea, respiratory discomfort, O 2 saturation <95%, diarrhea, vomiting, etc. was investigated; duration time (days) was quantified from the onset of symptoms to the date of notification.
The data was compiled into spreadsheets using the Microsoft Office Excel program.For analysis, the R statistical (R Core Team, 2020; v. 4.0.0)program was used.Logistic regression models were employed to determine factors associated with elderly ICU admissions; by definition of the method, and values one (1) and zero (0) were indicative of admission to the ICU and ward, respectively.
The logistic regression models applied in the univariate analysis (p<0.20) determined the choice of variables for constructing the multiple models resulting in the final model after applying the Stepwise method.Associations were estimated by calculating the odds ratio (OR), adopting the 95% confidence interval as a measure of precision. (9)he study linked to this research was approved by the Ethics Committee on Research with Human Beings (Opinion 4,214,589).The ethical precepts on research with human beings presented in Resolutions (466/2012 and 510/16) of the National Health Council were ensured in documentary-based studies using secondary data, thus ruling out the need for Free and Informed Consent Form (TCLE) (Certificate of Presentation of Ethical Assessment: 34787020.0.3001.5225).

Results
During the period evaluated, 46,099 elderly people with a positive diagnosis for COVID-19 were admitted in Paraná: 25,986 of them in the ward (56.4%) and 20,113 in the ICU (43.6%).Among patient characteristics (types of hospitalization), a significant difference was highlighted between gender distributions, with prevalent male admissions to the ward (50.9%) and ICU (56.0).The prevalence of elderly females showed a reduction in admissions to the ward (49.1%) and ICU (44.0%) (Table 1).Likewise, the race or self-declared skin color variable showed statistical significance.
Table 1 indicates that white race or skin color was the most admitted to the ward (84.9%) and ICU (83.0%).In both forms of treatment, indigenous people had a hospitalization prevalence of less than 1.0%, whereas those with yellow skin had a prevalence of less than 2.0% in general hospitalizations and between the two levels of treatment.
In table 1, greater hospitalization of elderly people with education equal to or greater than eight years of study can be noted.The use of antiviral drugs was low in admissions to the ward (8.6%) and ICU (8.1%), as well as having received at least one dose of flu vaccine (ward: 32.9%; ICU: 27.5%).In hospitalization, the vaccine against COVID-19 showed statistically significant differences, with higher percentages in non-vaccinated than in vaccinated people/patients.The municipality of residence was the same as that of hospitalization in the ward (68.7%)Upon admission to the ICU, not having taken an antiviral drug against influenza showed a 52.0%increase when compared to elderly people who took the medicine.Concerning clinical data, cardiovascular diseases increased the prevalence of the severe form by 35.0%, whereas lung diseases increased ICU admission by 64.0%.Obesity was associated with a 45.0% increase in ICU referrals.Dyspnea presented a 55.0% greater probability of developing the severe form of the disease.Cough showed a 36.0%reduction in ICU admissions, similar to loss of smell, with a 29.0%decrease in the need for ICU for treatment.Not living in the same municipality as hospitalization increased the chance of developing the severe form of COVID-19 by 34.0%.Likewise, a reduction in ICU referrals was observed in the north (35.0%), northwest (24.0%), and west (32.0%) macro-regions when compared to the east macroregion.

Discussion
Throughout the COVID-19 pandemic, hundreds of elderly people became infected.A significant part of this age group required hospital assistance due to the severity with which the disease manifested itself in the body.Some factors, including the sociodemographic, presence of comorbidity, and immunization factors, were associated with this need.
The results above show that the largest number of hospitalizations in the ward and ICU were male, with a small drop in female hospitalizations in the ward (49.1%) and ICU (44.0%).
The predominance of hospitalizations for COVID-19 in elderly men confirms the study that analyzed the epidemiological profile of cases reported in the southern region of the country (10) and the one that described the clinical-epidemiological profile of cases of hospital admission in the State of Paraíba. (11)In this state, the determinants responsible for the divergence in clinical outcomes of elderly people infected with SARS-CoV-2 according to sex have not yet been exactly established, despite the data presented and publications.and ICU (60.3%) hospitalizations.Table 2 shows the raw and adjusted Odd Ratios (OR).The variables sex, area of residence and use of antiviral drug for influenza were associated with the outcome, as well as having cardiovascular disease, kidney disease, lung disease, obesity, having had cough, dyspnea, loss of smell, living in the same municipality as that of hospitalization, and the health macro-region corresponding to the residence.Males had a 36.0%higher chance of admission to the ICU when compared to the chances of females, whereas rural areas of residence reduced the prevalence of ICU admission by 38.0%.The final outcome of hospitalizations due to COVID-19 was less distant; hospitalizations resulted in death (55.0%) and the disease was cured (44.6%), highlighting the high rate of deaths in elderly people admitted to the ICU (72.8%).We believe that the greater predisposition to worsening clinical conditions and deaths among men may be correlated with a set of hormonal, genetic, and lifestyle characteristics and the presence of comorbidities. (10)A netnographic study conducted in Brazil also detected that men are also more likely to present prolonged symptoms of COVID-19 in addition to this greater susceptibility, with a systemic impact on the body. (12)n addition to these factors, correlating the worsening of the clinical picture with the fact that women have twice as many genes that act in the immune system is also possible (the X chromosome has a greater quantity of these genes in the genome). (1)hen considering the self-declaration of race or skin color, the predominance in the worsening of the clinical condition in the elderly in the State of Paraná is among those who declared themselves white (ward: 84.9%; ICU: 83.0%), followed by brown or black people (ward: 13.8%; ICU: 15.5%), yellow (ward: 1.2%; ICU: 1.4%), and indigenous people (ward: 0.01%).
These data may be directly related to the numerical distribution of the sociodemographic surveys of the Brazilian Institute of Geography and Statistics (IBGE).Based on the National Household Sample Survey (PNAD; 2019), the Brazilian population is made up of white (42.7%), brown (46.8%), black (9.4%), and yellow or indigenous (1.1%) people. (13)he relationship between the proportion and number of people in Brazilian society and the number of people hospitalized due to the worsening of COVID-19 is only justified among those who declare themselves white, yellow, and indigenous people, as the difference between the number of self-declared brown or black people and the number of self-declared elderly people of this color is significant.The socioeconomic conditions of this population and the social inequalities that prevent or hinder access to healthcare may be one of the explanations, just as they prevent or hinder access to education, culture, employment, and leisure. (11)ifferently, a longitudinal study identified that the risk of mortality was similar for different ethnicities in the USA, which can be explained by the economic and social development of this country. (14)garding education, we found that the predominance of hospitalization due to COVID-19 in the elderly occurred in those who had less than 8 years of education (ward: 24.9%; ICU: 21.3%).A study carried out in Brazil stated that the transmission rates of respiratory diseases and infections are directly related to social inequality, contributing to understanding our epidemiological observation. (15)he incidence of hospitalizations in elderly people who used antiviral drugs against influenza is another important data; the vast majority of those who did not use antiviral drugs required medical treatment in a ward or ICU.The difference between elderly people who used antiviral drugs against influenza and those who did not is significant: 35,934 elderly people who did not use antiviral drugs required hospital medical treatment due to COVID-19.Treatment of COVID-19 patients requires exclusivity; developing pharmacological treatment is necessary to act on the target proteins of the virus.The World Health Organization (WHO) warned that we could live with the virus for decades; therefore, developing specific and safe treatments for the population is essential for the weapon against COVID-19 to be effective. (16)mong the signs and symptoms of the sample of elderly people hospitalized for COVID-19, the presence of dyspnea (70.8%), O 2 saturation <95% (66.3%), cough (61.7%), respiratory discomfort (52.5%), and fever (42.5%) stood out as the highest percentages in elderly people admitted to the ICU, indicating that the population in this age group is more susceptible to worsening of the disease.Despite the different clinical manifestations of COVID-19, around 80% of those infected may not have any symptoms.This requires constant monitoring of suspected cases so that the cases, in which the diagnosis of the disease is not certain, are not abandoned.Considering the diversity of clinical presentation that each elderly person may present, health services must establish criteria to better guide care, defining a set of actions based on the characteristics and symptoms that each elderly person is presenting. (17)he flu vaccine is also a factor in reducing cases of hospitalization of the elderly due to worsen-ing of the clinical condition of COVID-19, as the probability of admission of unvaccinated people (69.4%) to the ICU was greater than that of those vaccinated (30.6%).Regarding vaccination against COVID-19, the percentage of hospitalization of unvaccinated elderly people (55.3%) in the ICU was higher than that of vaccinated people, indicating that immunization can minimize the risks of hospitalization and the need for ICU.
After contamination by the virus, elderly people who did not receive any antiviral drug or had a vaccine against flu or COVID-19 were admitted to the ward and ICU.This points to an unfavorable prognostic outcome for elderly people who have not received any vaccine.We also emphasize that the spread of unreliable rumors and information has caused distrust and insecurity in a large part of the population. (18)A study carried out in Qatar (2022) showed that the propensity to develop severe COVID-19 in individuals vaccinated against influenza was about 90% lower than in those who were not vaccinated. (19) study on factors associated with an increase in the risk of death from COVID-19 (2020), showed that male individuals with a mean age equal to or greater/older than 66 years had a higher risk of death from the disease. (20)This correlates with the outcome of hospitalizations due to COVID-19 in the present study, in which patients who died (55.0%) and those who were cured of the disease (44.6%) obtained similar rates, highlighting the high death rate of people admitted to the ICU (72.8%).
The present study presented strengths and limitations that should be highlighted.Identification of the prevalence and factors associated with hospitalization of elderly people who acquired COVID-19 was the main advance in knowledge.Our findings can be used as a reference to evaluate and compare the health risk factors of the elderly population group in the current context and future pandemic contexts; they may also contribute to the analysis of factors associated with hospitalization of elderly people due to the disease in future studies.
The potential limitations found in the present study were as follows: data generated and inserted incorrectly into the system, missing data in the no-tification forms, and incorrect completion of the forms.

Conclusion
Education and non-adherence to vaccination against COVID-19 can increase the risk of hospitalization for the disease.The chance of ICU hospitalization for elderly men is greater than for elderly women.The non-use of antivirals can contribute to the worsening of the health of elderly people.Pre-existing cardiovascular and lung diseases and obesity contribute to worsening the disease with consequent admission to the ICU.Sociodemographic factors and underlying diseases influence the clinical outcome of the disease in this age group, contributing to hospitalization and possible referral to ICU.After suspected or confirmed COVID-19 in the elderly, health professionals must identify the factors that could lead to hospitalization, plan actions that prevent injuries, and monitor those infected, thus mitigating hospital effects and avoiding both overloads on the service and lack of beds for hospitalization.

Table 1 .
Characterization of the sample of elderly patients hospitalized for COVID-19