The rapid spread of Coronavirus Disease 2019 (COVID-19) worldwide was considered a pandemic [1, 2]. Numerous deaths occurred globally due to this disease [3]. Although the COVID-19 is fatal in all ages, it is much severe in elderly patients [4, 5].
Aging is among the critical risk factors for increased disease severity and mortality in patients with COVID-19 [6]. Comorbidity of a condition with chronic diseases in the elderly is a common health problem worldwide [7], especially in countries with higher life expectancy [8, 9].
Triage, patient prioritization, and reducing COVID-19-induced mortality are major challenges; thus, numerous studies have focused on the risk factors associated with COVID-19 outcomes in patients; however, data in elderly patients remains limited. Therefore, this study was performed to describe the demographic and clinical characteristics and to investigate the relationship between comorbidity and COVID-19 outcomes in the elderly.

This retrospective cohort study was conducted in patients aged ≥60 years s with COVID-19, hospitalized in Baharloo Hospital. All included patients were diagnosed with COVID-19 as per a positive Polymerase Chain Reaction (PCR) test, a typical view of COVID-19on Computer Tomography (CT) scan, or radiography data.
The research participants’ demographic data, including age, gender, Body Mass Index (BMI), disease severity, comorbidity with chronic diseases, and outcome variables, including the duration of hospitalization, a history of Intensive Care Unit (ICU) hospitalization, and disease outcome (death/alive) were collected from the admission records.
An Independent Samples t-test was used to compare the mean scores of the quantitative data between the dead and surviving groups. Besides, the Chi-squared test was used to investigate the relationship between qualitative variables and the death or survival of the explored patients. Analysis of Variance (ANOVA) was also used to compare the mean values of the quantitative variables in groups with one, ≥2, and without comorbidities. The logistic regression model was used to investigate the relationship between comorbidity and outcomes. The Kaplan–Meier and Logrank tests were used to report survival and compare survival in the elderly with/without underlying disease. STATA was used for data analysis; the significance level of <0.05 was bilaterally considered in all analyzes.

Overall, 522 elderly patients admitted to Baharloo Hospital were included in the present study. Approximately 77% (n=422) of the hospitalized elderly survived the disease, and 23% died. The Mean±SD age of the study participants was 72.55±8.44 years, and about 54%(281) of them were males. The age of the elderly who expired due to COVID-19 (76.31±8.66 y) was older than that in the surviving elderly (71.41±08.04 y), i.e., statistically significant (P<0.001) (Table 1).



Furthermore, a significantly higher proportion of the expired elderly patients had cardiovascular diseases, compared to the rest (P=0.011). Additionally, the mortality rate in the elderly with one or more underlying diseases was significantly higher than that in the elderly without such conditions (24.8% vs. 15.8%; P=0.032) (Table 2). 



Logistic regression analysis suggested that having cardiovascular disease increases the odds of death in the elderly by 1.07 (OR=1.07, 95%CI: 1.04-1.09); also, the odds of death in participants who had ≥2 underlying diseases was 1.69 (OR=1.69, 95%CI: 0.97-2.91, P=0.04) times higher than that in the elderly without such conditions, i.e., significant (Table 2). Moreover, the regression results for each outcome are presented in Table 2.
As shown in Figure 1, the survival rate of the patients without underlying diseases was higher than that in the patients with underlying diseases (Figure 1B). Besides, the frequencies of death and ICU hospitalization were directly related to the underlying diseases. Additionally, the elderly with a higher frequency of underlying diseases generated a higher mortality rate and ICU hospitalization (Figure 1C).

This study described the demographic and clinical characteristics and investigated the association between underlying diseases and the severity of COVID-19 in the elderly. Numerous studies suggested that the mortality rate in the elderly with COVID-19is much higher than that in the young population [4, 5, 10]. The obtained results also signified that approximately 23% of the elderly with COVID-19 expired, i.e., higher than the mortality rate in China, Korea, and Italy [4, 11].
Patients with COVID-19 usually die from various causes, including multiple organ failure, shock, respiratory failure, heart failure, arrhythmias, and renal failure [12, 13]. Previous studies indicated that a higher age can cause an inadequate response of the immune system to pathogens, the dysfunction of organs [14-17], and accelerated inflammation; eventually leading to multiple organ failure and death, and death in the ICU [18, 19].
Previous studies reported that comorbidity with other diseases may lead to a weakened immune system and the dysfunction of the body; thus, this condition presents higher adverse impacts in the elderly patient, compared to the young patients with COVID-19 [16, 17, 20, 21]. Previous studies, specified cardiovascular disease, obstructive pulmonary disease, hypertension, and diabetes as the most critical risk factors for the severity and mortality of COVID-19 [22].
    Sun et al. examined 3400 patients and reported similar results to ours [45]. Ruan et al. also explored 150 patients with COVID-19 and concluded that cardiovascular disease and hypertension were higher in patients who expired due to the disease, compared to the patients who were discharged (43% vs. 19%; P<0.001) [46]. A systematic review and meta-analysis study included 16 studies and 3994 patients; accordingly, the relevant data demonstrated that hypertension (OR=2.95), diabetes (OR=3.07), cardiovascular disease (OR=4.58), and chronic kidney disease (OR=5.32) generated a higher risk of mortality or undesirable outcomes in this group [47].
Finally, our results suggested that mortality is very high in the elderly with COVID-19. Chronic disease aggravates the prognosis in the elderly. Our results are expected to impact preventive interventions and take a more appropriate approach to prioritize older patients with risk factors, rather than adopting calendar age policies as a general indicator of risk. Furthermore, it seems that more care should be provided for the elderly with COVID-19 and underlying disease.
Ethical Considerations
Compliance with ethical guidelines
This study was approved by the Ethics Committee of the Tehran University of Medical Sciences (Code: IR.TUMS.VCR.REC.1399.148). All ethical principles are considered in this article. The participants were informed about the purpose of the research and its implementation stages. They were also assured about the confidentiality of their information and were free to leave the study whenever they wished, and if desired, the research results would be available to them.

This study was performed using the recorded data of the patients admitted to Baharloo Hospital and supported by the Tehran University of Medical Sciences.

Research of texts: Hamed Akhavizadegan and Mohammad Ghasem Roshanfekr Balalemi; Drafting of the article: Hamed Akhovizadegan, Mahmoud Aghaziarti and Zahra Boroujeni; Completion and correction of the draft article: Majid Janani and Fatemeh Taghizadeh; Data analysis: Issa Akbarzadeh Arab and Majid Janani; Editing, completion and final approval: All authors.

The authors declared no conflict of interest.

We would like to thank the staff and management of Baharloo Hospital who cooperated with us in the implementation of this project.
 

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