{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,13]],"date-time":"2026-06-13T20:37:44Z","timestamp":1781383064184,"version":"3.54.1"},"reference-count":41,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,2,4]],"date-time":"2025-02-04T00:00:00Z","timestamp":1738627200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Public Health"],"abstract":"<jats:sec><jats:title>Objectives<\/jats:title><jats:p>The study aimed to analyze in-hospital mortality (IHM) among all COVID-19 patients hospitalized in Spain between March 1, 2020, and December 31, 2021, and to compare two distinct periods: the prevaccination period (March 1, 2020, to January 31, 2021) and the vaccination period (February 1, 2021, to December 31, 2021). The objective was to assess the impact of vaccination on IHM and identify associated risk factors, using data from Spain\u2019s national hospitalization registry.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>This retrospective analysis used data from the Spanish National Surveillance System for Hospital Data. The primary outcome was in-hospital mortality (IHM). Multivariate logistic regression identified risk factors across the overall study period, as well as during the prevaccination and vaccination periods. Risk factors included age (in 20-year intervals), sex, comorbidities (e.g., hypertension, diabetes, chronic kidney failure, obesity, neurodegenerative disorders, and others), and admission to the intensive care unit.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>A total of 524,314 COVID-19 hospitalizations were recorded in Spain, with 329,690 during the prevaccination period and 194,624 during the vaccination period. Hospitalization rates dropped from 697\/100,000 people to 411\/100,000, and in-hospital mortality (IHM) decreased from 16.2 to 11.5% (adjusted odds ratio [AOR]: 0.71, 95% CI: 0.70\u20130.73, <jats:italic>p<\/jats:italic>\u202f&amp;lt;\u202f0.001). IHM rose with age, from 0.8% in patients aged 18\u201339 to 31.7% in those \u226580\u202fyears (<jats:italic>p<\/jats:italic>\u202f&amp;lt;\u202f0.001), but significant decreases were observed across all age groups after vaccination, especially in those \u226580\u202fyears (AOR: 0.76, 95% CI: 0.75\u20130.79, <jats:italic>p<\/jats:italic>\u202f&amp;lt;\u202f0.001). Risk factors for IHM remained consistent, with leukemia, neoplasm, and lymphoma posing the highest risks, while female sex (AOR: 0.75, 95% CI: 0.74\u20130.77, <jats:italic>p<\/jats:italic>\u202f&amp;lt;\u202f0.001) and dyslipidemia (AOR: 0.85, 95% CI: 0.32\u20130.86, <jats:italic>p<\/jats:italic>\u202f&amp;lt;\u202f0.001) were protective factors.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>During the vaccination period, the risk of in-hospital mortality (IHM) was 29% lower than in the prevaccination period, after adjusting for sex, age, and comorbidities. This reduced risk was observed across sexes, age groups, and comorbidities. The risk factors for IHM remained consistent between the two periods, with age as the main risk factor, while female sex and dyslipidemia were identified as protective factors.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fpubh.2025.1488283","type":"journal-article","created":{"date-parts":[[2025,2,4]],"date-time":"2025-02-04T06:32:15Z","timestamp":1738650735000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":1,"title":["A national population-based study of mortality and risk factors in COVID-19-hospitalized patients in Spain (2020\u20132021)"],"prefix":"10.3389","volume":"13","author":[{"given":"Jos\u00e9-Manuel","family":"Ramos-Rinc\u00f3n","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jos\u00e9","family":"S\u00e1nchez-Paya","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pilar","family":"Gonz\u00e1lez-De-La-Aleja","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Juan-Carlos","family":"Rodr\u00edguez-D\u00edaz","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Esperanza","family":"Merino","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2025,2,4]]},"reference":[{"key":"ref1","year":"2024"},{"key":"ref2","doi-asserted-by":"publisher","first-page":"e0248869","DOI":"10.1371\/journal.pone.0248869","article-title":"COVID19-ALC research group. Fatality and risk features for prognosis in COVID-19 according to the care approach - a retrospective cohort study","volume":"16","author":"Andr\u00e9s","year":"2021","journal-title":"PLoS One"},{"key":"ref3","doi-asserted-by":"publisher","first-page":"81","DOI":"10.1016\/j.ijid.2021.09.022","article-title":"Impact of scaling up SARS-CoV-2 vaccination on COVID-19 hospitalizations in Spain","volume":"112","author":"Barandalla","year":"2021","journal-title":"Int J Infect Dis"},{"key":"ref4","doi-asserted-by":"publisher","first-page":"17731","DOI":"10.1038\/s41598-023-42735-5","article-title":"Mortality reduction in older COVID-19-patients hospitalized in Spain during the second pandemic wave from the SEMI-COVID-19 registry","volume":"13","author":"Casas-Rojo","year":"2023","journal-title":"Sci Rep"},{"key":"ref5","doi-asserted-by":"publisher","first-page":"e28","DOI":"10.1093\/gerona\/glaa243","article-title":"Clinical characteristics and risk factors for mortality in very old patients hospitalized with COVID-19 in Spain","volume":"76","author":"Ramos-Rincon","year":"2021","journal-title":"J Gerontol A Biol Sci Med Sci"},{"key":"ref6","doi-asserted-by":"publisher","first-page":"630","DOI":"10.1093\/cid\/ciab493","article-title":"Risk factors for death among the first 80 543 coronavirus disease 2019 (COVID-19) cases in China: relationships between age, underlying disease, case severity, and region","volume":"74","author":"Zhang","year":"2022","journal-title":"Clin Infect Dis"},{"key":"ref7","doi-asserted-by":"publisher","first-page":"e0296895","DOI":"10.1371\/journal.pone.0296895","article-title":"Comorbidities and their association with COVID-19 mortality in Mexico between January 2020 and august 2021","volume":"19","author":"Lowhorn","year":"2024","journal-title":"PLoS One"},{"key":"ref8","doi-asserted-by":"publisher","first-page":"7804","DOI":"10.1038\/s41598-023-34613-x","article-title":"An observational study on factors associated with ICU mortality in Covid-19 patients and critical review of the literature","volume":"13","author":"Lavrentieva","year":"2023","journal-title":"Sci Rep"},{"key":"ref9","doi-asserted-by":"publisher","first-page":"899","DOI":"10.3390\/jcm10050899","article-title":"Gender-based differences by age range in patients hospitalized with COVID-19: A Spanish observational cohort study","volume":"10","author":"Josa-Laorden","year":"2021","journal-title":"J Clin Med"},{"key":"ref10","doi-asserted-by":"publisher","first-page":"75","DOI":"10.14423\/SMJ.0000000000001654","article-title":"Gender differences in hospital outcomes among COVID-19 hospitalizations","volume":"117","author":"Appunni","year":"2024","journal-title":"South Med J"},{"key":"ref11","doi-asserted-by":"publisher","first-page":"2284","DOI":"10.3390\/v14102284","article-title":"Comparative study of vaccinated and unvaccinated hospitalized patients: A retrospective population study of 500 hospitalized patients with SARS-CoV-2 infection in a Spanish population of 220,000 inhabitants","volume":"14","author":"Ruiz-Giardin","year":"2022","journal-title":"Viruses"},{"key":"ref12","doi-asserted-by":"publisher","first-page":"4834","DOI":"10.1038\/s41467-022-32458-y","article-title":"Trends in COVID-19 hospital outcomes in England before and after vaccine introduction, a cohort study","volume":"13","author":"Kirwan","year":"2022","journal-title":"Nat Commun"},{"key":"ref13","doi-asserted-by":"publisher","first-page":"426","DOI":"10.1186\/s12916-023-03119-8","article-title":"Impact of vaccination against severe COVID-19 in the French population aged 50 years and above: a retrospective population-based study","volume":"21","author":"Tan-Lhernould","year":"2023","journal-title":"BMC Med"},{"key":"ref14","doi-asserted-by":"publisher","first-page":"17384","DOI":"10.1038\/s41598-022-22145-9","article-title":"Characteristics of hospitalized patients with SARS-CoV-2 infection during successive waves of the COVID-19 pandemic in a reference hospital in Spain","volume":"12","author":"Iftimie","year":"2022","journal-title":"Sci Rep"},{"key":"ref15","doi-asserted-by":"publisher","first-page":"1437388","DOI":"10.3389\/fpubh.2024.1437388","article-title":"Assessing the impact of vaccines on COVID-19 efficacy in survival rates: a survival analysis approach for clinical decision support. 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Characteristics and outcome of COVID-19 patients admitted to the ICU: a nationwide cohort study on the comparison between the consecutive stages of the COVID-19 pandemic in the Netherlands, an update","volume":"14","author":"Termorshuizen","year":"2024","journal-title":"Ann Intensive Care"},{"key":"ref29","doi-asserted-by":"publisher","first-page":"1182","DOI":"10.15585\/mmwr.mm7137a4","article-title":"Mortality risk among patients hospitalized primarily for COVID-19 during the omicron and Delta variant pandemic periods \u2014 United States, April 2020\u2013June 2022","volume":"71","author":"Adjei","year":"2022","journal-title":"MMWR Morb Mortal Wkly Rep"},{"key":"ref30","doi-asserted-by":"publisher","first-page":"1303","DOI":"10.1016\/S0140-6736(22)00462-7","article-title":"Comparative analysis of the risks of hospitalization and death associated with SARS-CoV-2 omicron (B.1.1.529) and delta (B.1.617.2) variants in England: a cohort study","volume":"399","author":"Nyberg","year":"2022","journal-title":"Lancet"},{"key":"ref31","doi-asserted-by":"publisher","first-page":"454","DOI":"10.1186\/s12877-024-04982-7","article-title":"Modeling mortality prediction in older adults with dementia receiving COVID-19 vaccination","volume":"24","author":"Radomyslsky","year":"2024","journal-title":"BMC Geriatr"},{"key":"ref32","doi-asserted-by":"publisher","first-page":"1839","DOI":"10.3390\/v15091839","article-title":"Seven epidemic waves of COVID-19 in a Hospital in Madrid: analysis of severity and associated factors","volume":"15","author":"San Mart\u00edn-L\u00f3pez","year":"2023","journal-title":"Viruses"},{"key":"ref33","doi-asserted-by":"publisher","first-page":"855","DOI":"10.1186\/s12879-021-06536-3","article-title":"Mortality-related risk factors for COVID-19: a systematic review and meta-analysis of 42 studies and 423,117 patients","volume":"21","author":"Dessie","year":"2021","journal-title":"BMC Infect Dis"},{"key":"ref34","doi-asserted-by":"publisher","first-page":"811","DOI":"10.2147\/CLEP.S408510","article-title":"Is age the Most important risk factor in COVID-19 patients? The relevance of comorbidity burden: A retrospective analysis of 10,551 hospitalizations","volume":"15","author":"Valero-Bover","year":"2023","journal-title":"Clin Epidemiol"},{"key":"ref35","doi-asserted-by":"publisher","first-page":"100747","DOI":"10.1016\/j.lanepe.2023.100747","article-title":"Impact of COVID-19 on immunocompromised populations during the omicron era: insights from the observational population-based INFORM study","volume":"35","author":"Evans","year":"2023","journal-title":"Lancet Reg Health Eur"},{"key":"ref36","doi-asserted-by":"publisher","first-page":"e0249231","DOI":"10.1371\/journal.pone.0249231","article-title":"Risk factors for in-hospital mortality in laboratory-confirmed COVID-19 patients in the Netherlands: A competing risk survival analysis","volume":"16","author":"Nijman","year":"2021","journal-title":"PLoS One"},{"key":"ref37","doi-asserted-by":"publisher","first-page":"e1259","DOI":"10.1002\/iid3.1259","article-title":"Immunocompromised individuals are at increased risk of COVID-19 breakthrough infection, hospitalization, and death in the postvaccination era: A systematic review","volume":"12","author":"Bytyci","year":"2024","journal-title":"Immun Inflamm Dis"},{"key":"ref38","doi-asserted-by":"publisher","first-page":"155812","DOI":"10.1016\/j.metabol.2024.155812","article-title":"Mortality risk in patients with obesity and COVID-19 infection: a systematic review and meta-analysis","volume":"155","author":"Haber","year":"2024","journal-title":"Metabolism"},{"key":"ref39","doi-asserted-by":"publisher","first-page":"966","DOI":"10.1016\/j.amjmed.2024.06.002","article-title":"Adjunctive statin therapy in patients with Covid-19: A systematic review and Meta-analysis of randomized controlled trials","volume":"137","author":"De Mesquita","year":"2024","journal-title":"Am J Med"},{"key":"ref40","doi-asserted-by":"publisher","first-page":"1607063","DOI":"10.3389\/ijph.2024.1607063","article-title":"Gender\/sex disparities in the COVID-19 Cascade from testing to mortality: an intersectional analysis of Swiss surveillance data","volume":"69","author":"Auderset","year":"2024","journal-title":"Int J Public Health"},{"key":"ref41","doi-asserted-by":"publisher","first-page":"429","DOI":"10.1111\/imm.13487","article-title":"The immune response to COVID-19: does sex matter?","volume":"166","author":"Ho","year":"2022","journal-title":"Immunology"}],"container-title":["Frontiers in Public Health"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fpubh.2025.1488283\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,2,4]],"date-time":"2025-02-04T06:32:18Z","timestamp":1738650738000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fpubh.2025.1488283\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,2,4]]},"references-count":41,"alternative-id":["10.3389\/fpubh.2025.1488283"],"URL":"https:\/\/doi.org\/10.3389\/fpubh.2025.1488283","relation":{},"ISSN":["2296-2565"],"issn-type":[{"value":"2296-2565","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,2,4]]},"article-number":"1488283"}}