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BMC Infect Dis
. 2024 Sep 27;24(1):1052.
doi: 10.1186/s12879-024-09865-1. Comprehensive statistical analysis reveals significant benefits of COVID-19 vaccination in hospitalized patients: propensity score, covariate adjustment, and feature importance by permutation
Eduardo Villela de Moraes 1 , Magda Carvalho Pires 2 , Amanda Abrantes Abreu Costa 3 , Aline Gabrielle Sousa Nunes 4 , Caroline Lopes de Amorim 5 , Euler Roberto Fernandes Manenti 6 7 , Fernanda Barbosa Lucas 8 , Fernanda d'Athayde Rodrigues 9 , Fernando Anschau 10 11 , Guilherme Fonseca do Nascimento 12 , Giovanna Grunewald Vietta 13 , Jessica Fernandes Benavides Moreira 14 , Karen Brasil Ruschel 6 7 15 , Monica Aparecida Costa 16 , Pamela Andrea Alves Duraes 17 , Pedro Augusto Van Der Sand Germani 18 , Priscilla Pereira Dos Reis 19 , Rochele Mosmann Menezes 20 , Leonardo Chaves Dutra da Rocha 12 21 , Marcos André Gonçalves 22 , Unaí Tupinambas 3 , Milena Soriano Marcolino 3 15 23
Affiliations
Background: COVID-19 vaccines effectively prevent infection and hospitalization. However, few population-based studies have compared the clinical characteristics and outcomes of patients hospitalized for COVID-19 using advanced statistical methods. Our objective is to address this evidence gap by comparing vaccinated and unvaccinated patients hospitalized for COVID-19.
Methods: This retrospective cohort included adult COVID-19 patients admitted from March 2021 to August 2022 from 27 hospitals. Clinical characteristics, vaccination status, and outcomes were extracted from medical records. Vaccinated and unvaccinated patients were compared using propensity score analyses, calculated based on variables associated with vaccination status and/or outcomes, including waves. The vaccination effect was also assessed by covariate adjustment and feature importance by permutation.
Results: From the 3,188 patients, 1,963 (61.6%) were unvaccinated and 1,225 (38.4%) were fully vaccinated. Among these, 558 vaccinated individuals were matched with 558 unvaccinated ones. Vaccinated patients had lower rates of mortality (19.4% vs. 33.3%), invasive mechanical ventilation (IMV-18.3% vs. 34.6%), noninvasive mechanical ventilation (NIMV-10.6% vs. 22.0%), intensive care unit admission (ICU-32.0% vs. 44.1%) vasoactive drug use (21.1% vs. 32.6%), dialysis (8.2% vs. 14.7%) hospital length of stay (7.0 vs. 9.0 days), and thromboembolic events (3.9% vs.7.7%), p < 0.05 for all. Risk-adjusted multivariate analysis demonstrated a significant inverse association between vaccination and in-hospital mortality (adjusted odds ratio [aOR] = 0.42, 95% confidence interval [CI]: 0.31-0.56; p < 0.001) as well as IMV (aOR = 0.40, 95% CI: 0.30-0.53; p < 0.001). These results were consistent in all analyses, including feature importance by permutation.
Conclusion: Vaccinated patients admitted to hospital with COVID-19 had significantly lower mortality and other severe outcomes than unvaccinated ones during the Delta and Omicron waves. These findings have important implications for public health strategies and support the critical importance of vaccination efforts, particularly in low-income countries, where vaccination coverage remains suboptimal.
Keywords: Brazil; COVID-19; Hospitalizations; Machine learning; Mortality; Propensity score; SARS-CoV-2; Severe illness; Vaccine.
. 2024 Sep 27;24(1):1052.
doi: 10.1186/s12879-024-09865-1. Comprehensive statistical analysis reveals significant benefits of COVID-19 vaccination in hospitalized patients: propensity score, covariate adjustment, and feature importance by permutation
Eduardo Villela de Moraes 1 , Magda Carvalho Pires 2 , Amanda Abrantes Abreu Costa 3 , Aline Gabrielle Sousa Nunes 4 , Caroline Lopes de Amorim 5 , Euler Roberto Fernandes Manenti 6 7 , Fernanda Barbosa Lucas 8 , Fernanda d'Athayde Rodrigues 9 , Fernando Anschau 10 11 , Guilherme Fonseca do Nascimento 12 , Giovanna Grunewald Vietta 13 , Jessica Fernandes Benavides Moreira 14 , Karen Brasil Ruschel 6 7 15 , Monica Aparecida Costa 16 , Pamela Andrea Alves Duraes 17 , Pedro Augusto Van Der Sand Germani 18 , Priscilla Pereira Dos Reis 19 , Rochele Mosmann Menezes 20 , Leonardo Chaves Dutra da Rocha 12 21 , Marcos André Gonçalves 22 , Unaí Tupinambas 3 , Milena Soriano Marcolino 3 15 23
Affiliations
- PMID: 39333931
- PMCID: PMC11428431
- DOI: 10.1186/s12879-024-09865-1
Background: COVID-19 vaccines effectively prevent infection and hospitalization. However, few population-based studies have compared the clinical characteristics and outcomes of patients hospitalized for COVID-19 using advanced statistical methods. Our objective is to address this evidence gap by comparing vaccinated and unvaccinated patients hospitalized for COVID-19.
Methods: This retrospective cohort included adult COVID-19 patients admitted from March 2021 to August 2022 from 27 hospitals. Clinical characteristics, vaccination status, and outcomes were extracted from medical records. Vaccinated and unvaccinated patients were compared using propensity score analyses, calculated based on variables associated with vaccination status and/or outcomes, including waves. The vaccination effect was also assessed by covariate adjustment and feature importance by permutation.
Results: From the 3,188 patients, 1,963 (61.6%) were unvaccinated and 1,225 (38.4%) were fully vaccinated. Among these, 558 vaccinated individuals were matched with 558 unvaccinated ones. Vaccinated patients had lower rates of mortality (19.4% vs. 33.3%), invasive mechanical ventilation (IMV-18.3% vs. 34.6%), noninvasive mechanical ventilation (NIMV-10.6% vs. 22.0%), intensive care unit admission (ICU-32.0% vs. 44.1%) vasoactive drug use (21.1% vs. 32.6%), dialysis (8.2% vs. 14.7%) hospital length of stay (7.0 vs. 9.0 days), and thromboembolic events (3.9% vs.7.7%), p < 0.05 for all. Risk-adjusted multivariate analysis demonstrated a significant inverse association between vaccination and in-hospital mortality (adjusted odds ratio [aOR] = 0.42, 95% confidence interval [CI]: 0.31-0.56; p < 0.001) as well as IMV (aOR = 0.40, 95% CI: 0.30-0.53; p < 0.001). These results were consistent in all analyses, including feature importance by permutation.
Conclusion: Vaccinated patients admitted to hospital with COVID-19 had significantly lower mortality and other severe outcomes than unvaccinated ones during the Delta and Omicron waves. These findings have important implications for public health strategies and support the critical importance of vaccination efforts, particularly in low-income countries, where vaccination coverage remains suboptimal.
Keywords: Brazil; COVID-19; Hospitalizations; Machine learning; Mortality; Propensity score; SARS-CoV-2; Severe illness; Vaccine.