Characterization of the epidemiological curve of the 1st wave of the pandemic - study of the determinants for death and hospitalization due to COVID-19 in Portugal
Abstract
COVID-19 is an infectious disease caused by the SARS-CoV-2 virus that emerged in China and has since spread rapidly to all countries in the world. The aim of this study is to characterize the peak of the first wave of the pandemic using some demographic and clinical determinants. The database studied contains epidemiological surveillance data of COVID-19 from Portugal until June 30, 2020. The peak of the pandemic was determined considering the number of diagnoses, deaths, and hospitalizations over time, and the estimated period for the first wave was between March 19 and April 24. Logistic regression models were performed to estimate the univariate and multivariate Odds Ratio (OR) and the respective 95% confidence intervals (95% CI) for this period and for each of the variables considered in relation to both study outcomes: mortality (5.8%) and hospitalization (18.8%). The main risk factors considered for the mortality outcome were: Age Group (≥ 80 years: OR = 11.978; 65-79 years: OR = 4.064; Ref. G.: <64 years:), Hospitalization (OR = 6.479) and Comorbidities (OR = 5.735). For the outcome hospitalization, the main risk factors were: Age Group (≥ 80 years: OR =
8.537; 65-79 years: OR = 3.899; Ref. G.: <64 years), male gender (OR= 1.575) and Comorbidities (OR = 5.193). The proposed models presented high area under curves (AUC) results (mortality: AUC=91.05%; and hospitalization: AUC=84.5%), with small amplitudes in the 95% CI. The present study demonstrated that, overall, the major risk factors associated with worse prognostics of COVID-19 were advanced age (over 65 years), and the existence of comorbidities. For the risk of hospitalizations, the male gender was also a significant risk factor.
Copyright (c) 2021 Francisca Monteiro Freire, Vera Afreixo, Pedro Sá Couto

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
When submitting an article to the Journal of Statistics on Health Decision (JSHD), authors certify the following clauses:
- Originality and single submission – The contents presented in the article have not been published previously in whole or in part, and were not submitted or are not under active consideration elsewhere prior JSHD decision. The article is authentic and does not contain plagiarism.
- Authorship – All authors reviewed the article, agreed with its content, and agreed to its submission to the JSHD. All the authorship criteria stated by The International Committee of Medical Journal Editors Guidelines were met.
- Conflicts of interest – Any conflict of interests were declared. If authors have no declaration, it should be written (in the acknowledgements section): “The authors declare no conflict of interests”.
- Ethics committee and informed consent (if applicable) – The current research was approved by an independent ethics committee and subjects gave their informed consent before they were enrolled in the study.
- And authors agree to the Open Access license agreement of the Journal of Statistics on Health Decision, stated bellow.