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Observational Study
. 2022 Nov 7;12(1):18918.
doi: 10.1038/s41598-022-23312-8.

Mortality among hospitalized COVID-19 patients during surges of SARS-CoV-2 alpha (B.1.1.7) and delta (B.1.617.2) variants

Alireza Zali  1 , Mahmood Khodadoost  2 , Saeid Gholamzadeh  3   4 , Shahriar Janbazi  5 , Hassan Piri  6 , Nazanin Taraghikhah  7 , Khatereh Hannani  8 , Mehdi Azizmohammad Looha  9 , Gohar Mohammadi  10
Affiliations
Observational Study

Mortality among hospitalized COVID-19 patients during surges of SARS-CoV-2 alpha (B.1.1.7) and delta (B.1.617.2) variants

Alireza Zali et al. Sci Rep. .

Abstract

The aim of this study was to evaluate the death proportion and death risk of COVID-19 hospitalized patients over time and in different surges of COVID-19. This multi-center observational study was conducted from March 21, 2021 to October 3, 2021 which included the alpha and delta SARS-CoV-2 surges occurred in April and August in Tehran, respectively. The risk of COVID-19 death was compared in different months of admission. A total of 270,624 patients with COVID-19, of whom 6.9% died, were admitted to hospitals in Tehran province. Compared to patients admitted in March, a higher risk of COVID-19 death was observed among patients admitted to the hospital in July (HR 1.28; 95% CI 1.17, 1.40), August (HR 1.40; 95% CI 1.28, 1.52), September (HR 1.37; 95% CI 1.25, 1.50) and October (HR 4.63; 95% CI 2.77, 7.74). The ICU death proportion was 36.8% (95% CI: 35.5, 38.1) in alpha surge and increased significantly to 39.8 (95% CI 38.6, 41.1) in delta surge. The risk of COVID-19 death was significantly higher in delta surge compared to alpha surge (HR 1.22; 95% CI 1.17, 1.27). Delta surge was associated with a higher risk of death compared to alpha surge. High number of hospitalizations, a shortage of hospital beds, ICU spaces and medical supplies, poor nutritional status of hospitalized patients, and lack of the intensivist physicians or specialized nurses in the ICU were factors that contributed to the high mortality rate in the delta surge in Iran.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
Density plot of patients’ frequency per Month during the study period. (A) Hospital admissions per month, (B) by death status, (C) by age group, and (D) by wards of hospital.
Figure 2
Figure 2
The forest plot of death hazard ratio among hospitalized patients of COVID-19. The Cox proportional model was adjusted for month of admission, sex, age, no. of comorbidities and nationality.
Figure 3
Figure 3
The trend of unadjusted death proportion due to COVID-19 among hospitalized patients per month. Error bars are the 95% confidence interval for death proportions.
Figure 4
Figure 4
The adjusted HR and 95% CI of death among hospitalized COVID-19 patients by wards. The Cox proportional model was adjusted by variables including sex, age, No. of comorbidities and nationality.
Figure 5
Figure 5
The death proportion and 95% confidence interval due to COVID-19 among hospitalized patients by sex, age, no. of comorbidities, and nationality.
Figure 6
Figure 6
The overall death proportion (%) due to COVID-19 by Tehran County (upper panel). The monthly death proportion due to COVID-19 with 95% confidence interval by Tehran County (lower panel).
Figure 7
Figure 7
The subgroup HR and 95% CI of death among hospitalized COVID-19 patients by different group of age, sex, No. of comorbidities and nationality.
Figure 7
Figure 7
The subgroup HR and 95% CI of death among hospitalized COVID-19 patients by different group of age, sex, No. of comorbidities and nationality.
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Supplementary concepts