key: cord-315397-cm3mc7we
authors: Park, H. C.; Kim, D. H.; Cho, A.; Kim, J.; Yun, K.-s.; Lee, Y.-K.
title: Clinical Outcome of Asymptomatic COVID-19 Infection Among a Large Nationwide Cohort of 5,621 Hospitalized Patients in Korea
date: 2020-10-27
journal: nan
DOI: 10.1101/2020.10.25.20218982
sha: 
doc_id: 315397
cord_uid: cm3mc7we

We investigated clinical outcome of asymptomatic coronavirus disease 2019 (COVID-19) and identified risk factors associated with high patient mortality using Korean nationwide public database of 5,621 hospitalized patients. The mortality rate and admission rate to intensive care unit were compared between asymptomatic and symptomatic patients. The prediction model for patient mortality was developed through risk factor analysis among asymptomatic patients. The prevalence of asymptomatic COVID-19 infection was 25.8%. The mortality rates were not different between groups (3.3% vs. 4.5%, p=0.17). However, symptomatic patients were more likely to receive ICU care compared to asymptomatic patients (4.1% vs. 1.0%, p<0.0001). The age-adjusted Charlson comorbidity index score (CCIS) was the most potent predictor for patient mortality in asymptomatic patients. The clinicians should predict the risk of death by evaluating age and comorbidities but not the presence of symptoms.

The Kaplan-Meier method was used to compare death-free survival curves, and 1 1 9 differences were assessed utilizing the log-rank test. We used univariate and multivariate Cox 1 2 0 proportional hazard model to estimate risk factors associated with patient mortality. Age was 1 2 1 excluded from the multivariate analysis because of its potential interaction with CCIS. We used 1 2 2 univariate and multivariate logistic regression models to evaluate the risk factors for ICU 1 2 3 admission. A nomogram to predict 14-day and 28-day mortality risk of the patient was built 1 2 4 based on the variables found in multivariate Cox proportional hazard model. In the nomogram, 1 2 5 All rights reserved. No reuse allowed without permission.

(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted October 27, 2020. ; https://doi.org/10.1101 https://doi.org/10. /2020 Reserved space. Do not place any text in this section. Include the mandatory author checklist or your manuscript will be returned. Use continuous line numbering in your manuscript.

CCIS was used as a continuous variable to check the impact per score. The maximum score of 1 2 6 each variable was set as 100. The performance of the nomogram was measured based on the 1 2 7

Harrell concordance index (C-index). The nomogram was validated in calibration plots with 1 2 8 1,000 bootstrap samples in which the estimated survival probability was compared with the 1 2 9 observed value. All statistical analysis was performed by using R version 4.0.2 (R Foundation 1 3 0 for Statistical Computing; http://www.r-project.org/). P value <0.05 was considered statistically In a total of 5,621 patients, asymptomatic patients were 1,449 (25.8%) and symptomatic 1 3 5 patients were 4,172 (74.2%). Baseline characteristics were compared between asymptomatic and 1 3 6 symptomatic patients (Table 1 ). In the asymptomatic group, the proportions of patients under the 1 3 7 age of 30 (30.0%) and over 70 years of age (17.5%) were greater than those in symptomatic proportion of patients with low BMI (<18.5 kg/m 2 ) was greater in asymptomatic group than that 1 4 1 of symptomatic group. Asymptomatic patients had higher prevalence of dementia and lower 1 4 2 prevalence of asthma than symptomatic group. In addition, the absolute lymphocyte and platelet 1 4 3 counts were significantly lower in symptomatic patients compared to asymptomatic patients. In (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted October 27, 2020. ; 1 7 8 showed that CCIS was the most important factor contributing to the prognosis followed by the 1 7 9 thrombocytopenia, lymphocytopenia, and anemia. The C-index value for prediction of overall This study examined the incidence of mortality and ICU admission among asymptomatic 1 8 4 and symptomatic patients during hospitalization due to COVID-19 infection in Korea. The 1 8 5 mortality rate in asymptomatic patients was as high as that in symptomatic patients (3.3% vs. to that in asymptomatic patients (4.1% vs. 1.0%, P<0.0001). The CCIS was the most potent 1 8 8 predictor for mortality in asymptomatic patients.

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(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. To our knowledge, this is the first study to evaluate incidence of mortality and its risk diagnosis was not as important as age or comorbidities in prediction of patient mortality. However, symptomatic patients at admission were more likely to receive ICU care. Previous 2 0 1 study inferred that patients may spread virus 1 to 3 days before symptom development, and the 2 0 2 duration of infectious period may be 6.5 to 9.6 days in asymptomatic patients (16). Another German researchers found that the duration of viral shedding was not related to viral replication 2 1 0 and isolation from tissue (19). Therefore, a complex dynamic between the virus and immune 2 1 1 reaction of the host may underlie the severity of the disease and clinical course of COVID-19. In 2 1 2 All rights reserved. No reuse allowed without permission.

(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted October 27, 2020. ; https://doi.org/10.1101 https://doi.org/10. /2020 Reserved space. Do not place any text in this section. Include the mandatory author checklist or your manuscript will be returned. Use continuous line numbering in your manuscript. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted October 27, 2020. ; https://doi.org/10.1101 https://doi.org/10. /2020 Reserved space. Do not place any text in this section. Include the mandatory author checklist or your manuscript will be returned. Use continuous line numbering in your manuscript. All rights reserved. No reuse allowed without permission.

(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted October 27, 2020. ; https://doi.org/10. 1101 /2020 

Do not place any text in this section. Include the mandatory author checklist or your manuscript will be returned. Use continuous line numbering in your manuscript