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<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ali="http://www.niso.org/schemas/ali/1.0/" article-type="research-article" dtd-version="1.2" xml:lang="en"><front><journal-meta><journal-id journal-id-type="publisher-id">Epidemiology and Infectious Diseases</journal-id><journal-title-group><journal-title xml:lang="en">Epidemiology and Infectious Diseases</journal-title><trans-title-group xml:lang="ru"><trans-title>Эпидемиология и инфекционные болезни</trans-title></trans-title-group></journal-title-group><issn publication-format="print">3034-2007</issn><issn publication-format="electronic">3034-2015</issn><publisher><publisher-name xml:lang="en">Eco-Vector</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="publisher-id">688872</article-id><article-id pub-id-type="doi">10.17816/EID688872</article-id><article-id pub-id-type="edn">SQADTK</article-id><article-categories><subj-group subj-group-type="toc-heading" xml:lang="en"><subject>Original study articles</subject></subj-group><subj-group subj-group-type="toc-heading" xml:lang="ru"><subject>Оригинальные исследования</subject></subj-group><subj-group subj-group-type="article-type"><subject>Research Article</subject></subj-group></article-categories><title-group><article-title xml:lang="en">Predictors of severe COVID-19: older age and comorbidity</article-title><trans-title-group xml:lang="ru"><trans-title>Пожилой возраст и коморбидность как предикторы тяжёлого течения COVID-19</trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-4978-4139</contrib-id><contrib-id contrib-id-type="spin">6228-2241</contrib-id><name-alternatives><name xml:lang="en"><surname>Konnov</surname><given-names>Vladislav V.</given-names></name><name xml:lang="ru"><surname>Коннов</surname><given-names>Владислав Владиславович</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>MD</p></bio><email>konnov.vlad@gmail.com</email><xref ref-type="aff" rid="aff3"/><xref ref-type="aff" rid="aff2"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0003-3766-1868</contrib-id><contrib-id contrib-id-type="spin">6583-0476</contrib-id><name-alternatives><name xml:lang="en"><surname>Tsygankova</surname><given-names>Anna E.</given-names></name><name xml:lang="ru"><surname>Цыганкова</surname><given-names>Анна Эдуардовна</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>MD, Cand. Sci. (Medicine);</p></bio><bio xml:lang="ru"><p>канд. мед. наук</p></bio><email>anna.tsygankova.inf@gmail.com</email><xref ref-type="aff" rid="aff3"/><xref ref-type="aff" rid="aff2"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0003-4549-7172</contrib-id><contrib-id contrib-id-type="spin">4742-1459</contrib-id><name-alternatives><name xml:lang="en"><surname>Gerasimov</surname><given-names>Andrey N.</given-names></name><name xml:lang="ru"><surname>Герасимов</surname><given-names>Андрей Николаевич</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>Dr. Sci. (Physics and Mathematics), Assistant Professor</p></bio><bio xml:lang="ru"><p>д-р физ.-мат. наук, доцент</p></bio><email>andr-gerasim@yandex.ru</email><xref ref-type="aff" rid="aff4"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0009-0005-9764-8106</contrib-id><name-alternatives><name xml:lang="en"><surname>Timonina</surname><given-names>Ksenia A.</given-names></name><name xml:lang="ru"><surname>Тимонина</surname><given-names>Ксения Александровна</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><email>ksuchatimonina@gmail.com</email><xref ref-type="aff" rid="aff2"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0003-3323-3401</contrib-id><contrib-id contrib-id-type="spin">5322-6167</contrib-id><name-alternatives><name xml:lang="en"><surname>Tsvetkova</surname><given-names>Natalia A.</given-names></name><name xml:lang="ru"><surname>Цветкова</surname><given-names>Наталья Александровна</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>MD, Cand. Sci. (Medicine);</p></bio><bio xml:lang="ru"><p>канд. мед. наук</p></bio><email>3655192@mail.ru</email><xref ref-type="aff" rid="aff3"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-4771-9616</contrib-id><contrib-id contrib-id-type="spin">6105-8492</contrib-id><name-alternatives><name xml:lang="en"><surname>Potekaeva</surname><given-names>Svetlana A.</given-names></name><name xml:lang="ru"><surname>Потекаева</surname><given-names>Светлана Александровна</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>MD, Dr. Sci. (Medicine)</p></bio><bio xml:lang="ru"><p>д-р мед. наук</p></bio><email>infection_mma@mail.ru</email><xref ref-type="aff" rid="aff3"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0003-0902-9267</contrib-id><contrib-id contrib-id-type="spin">3197-9205</contrib-id><name-alternatives><name xml:lang="en"><surname>Umbetova</surname><given-names>Karina T.</given-names></name><name xml:lang="ru"><surname>Умбетова</surname><given-names>Карина Туракбаевна</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>MD, Dr. Sci. (Medicine), Professor</p></bio><bio xml:lang="ru"><p>д-р мед. наук, профессор</p></bio><email>karinasara@inbox.ru</email><xref ref-type="aff" rid="aff2"/></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0003-4581-4510</contrib-id><contrib-id contrib-id-type="spin">3342-4681</contrib-id><name-alternatives><name xml:lang="en"><surname>Volchkova</surname><given-names>Elena V.</given-names></name><name xml:lang="ru"><surname>Волчкова</surname><given-names>Елена Васильевна</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>MD, Dr. Sci (Medicine), Professor</p></bio><bio xml:lang="ru"><p>д-р мед. наук, профессор</p></bio><email>antononina@rambler.ru</email><xref ref-type="aff" rid="aff2"/></contrib></contrib-group><aff-alternatives id="aff1"><aff><institution xml:lang="en">Infectious Clinical Hospital No 2, Moscow</institution></aff><aff><institution xml:lang="ru">Инфекционная клиническая больница № 2, Москва</institution></aff><aff><institution xml:lang="zh"></institution></aff></aff-alternatives><aff-alternatives id="aff2"><aff><institution xml:lang="en">Sechenov First Moscow State Medical University</institution></aff><aff><institution xml:lang="ru">Первый Московский государственный медицинский университет им. И.М. Сеченова (Сеченовский Университет)</institution></aff></aff-alternatives><aff-alternatives id="aff3"><aff><institution xml:lang="en">Infectious Clinical Hospital No 2, Moscow</institution></aff><aff><institution xml:lang="ru">Инфекционная клиническая больница № 2, Москва</institution></aff></aff-alternatives><aff-alternatives id="aff4"><aff><institution xml:lang="en">Centre for Strategic Planning and Management of Biomedical Health Risks</institution></aff><aff><institution xml:lang="ru">Центр стратегического планирования и управления медико-биологическими рисками здоровью ФМБА</institution></aff></aff-alternatives><pub-date date-type="preprint" iso-8601-date="2025-12-14" publication-format="electronic"><day>14</day><month>12</month><year>2025</year></pub-date><pub-date date-type="pub" iso-8601-date="2025-12-30" publication-format="electronic"><day>30</day><month>12</month><year>2025</year></pub-date><volume>30</volume><issue>3</issue><issue-title xml:lang="en"/><issue-title xml:lang="ru"/><fpage>180</fpage><lpage>193</lpage><history><date date-type="received" iso-8601-date="2025-08-25"><day>25</day><month>08</month><year>2025</year></date><date date-type="accepted" iso-8601-date="2025-10-29"><day>29</day><month>10</month><year>2025</year></date></history><permissions><copyright-statement xml:lang="en">Copyright ©; 2026, Eco-vector</copyright-statement><copyright-statement xml:lang="ru">Copyright ©; 2026, Эко-вектор</copyright-statement><copyright-year>2026</copyright-year><copyright-holder xml:lang="en">Eco-vector</copyright-holder><copyright-holder xml:lang="ru">Эко-вектор</copyright-holder><ali:free_to_read xmlns:ali="http://www.niso.org/schemas/ali/1.0/" start_date="2029-01-07"/><license><ali:license_ref xmlns:ali="http://www.niso.org/schemas/ali/1.0/">https://creativecommons.org/licenses/by-nc-nd/4.0</ali:license_ref></license></permissions><self-uri xlink:href="https://rjeid.com/1560-9529/article/view/688872">https://rjeid.com/1560-9529/article/view/688872</self-uri><abstract xml:lang="en"><p><bold>BACKGROUND: </bold>Older age and comorbidity are recognized as significant risk factors for severe COVID-19. However, the combined impact of these factors on disease outcomes, especially in different age groups, remains unclear. This study focuses on older patients with chronic comorbidities in order to address this gap.</p> <p><bold>AIM:</bold> This study aimed to evaluate the role of older age and comorbidities in prediction of severe COVID-19 and mortality in hospitalized patients.</p> <p><bold>METHODS:</bold> This cross-sectional, retrospective study included 604 patients aged 18–99 years who were treated at Infectious Diseases Clinical Hospital No. 2 of the Moscow Healthcare Department for laboratory-confirmed (ICD-10 code: U07.1) COVID-19 between September 2020 and November 2022. Demographic characteristics, comorbidities, clinical outcomes (recovery, improvement, and mortality rates), and COVID-19 severity were evaluated.</p> <p><bold>RESULTS:</bold> An analysis of 604 hospitalized patients revealed an increase in mortality rates with age: 4.1% in patients under 60 years old, 12.7% in patients aged 60–74 years, 16.4% in patients aged 75–89 years, and 21.9% in patients aged 90 years and older. The most common comorbidity-associated risk factors included chronic kidney disease (mortality rate: 23.2%), myocardial ischemia (19.7%), and type 2 diabetes mellitus (18%). The infection was atypical, without fever in 21% of patients, primarily those in the older age group. Stratified analysis showed that the role of specific risk factors, such as chemotherapy, myocardial ischemia, and chronic kidney disease, varied across age groups.</p> <p><bold>CONCLUSION:</bold> Older age and comorbidities are independent risk factors for severe COVID-19 and fatal outcomes. Patients over the age of 75 years with chronic diseases require special attention. Early diagnosis and personalized management strategies may improve outcomes in this age group.</p></abstract><trans-abstract xml:lang="ru"><p><bold>Обоснование.</bold> Пожилой возраст и коморбидность признаны значимыми факторами риска тяжёлого течения COVID-19. Однако их совместное влияние на исходы заболевания, особенно в различных возрастных подгруппах, остаётся недостаточно изученным. Настоящее исследование направлено на восполнение этого пробела и уделяет особое внимание пациентам старшего возраста с множественными хроническими заболеваниями.</p> <p><bold>Цель исследования.</bold> Оценить роль пожилого возраста и коморбидной патологии в качестве предикторов тяжёлого течения COVID-19 и летальных исходов среди госпитализированных пациентов.</p> <p><bold>Методы.</bold> В одномоментное исследование с ретроспективным анализом данных включили 604 пациента в возрасте от 18 до 99 лет с лабораторно подтверждённым COVID-19 (код по МКБ-10: U07.1), проходивших лечение в Государственном бюджетном учреждении здравоохранения «Инфекционная клиническая больница № 2 Департамента здравоохранения города Москвы» с сентября 2020 по ноябрь 2022 года. Анализировали демографические данные, коморбидные состояния, клинические исходы (выздоровление, улучшение состояния, летальность) и степень тяжести заболевания.</p> <p><bold>Результаты.</bold> Анализ выборки из 604 госпитализированных пациентов выявил увеличение летальности с возрастом: 4,1% среди лиц &lt;60 лет, 12,7% в группе 60–74 лет, 16,4% в группе 75–89 лет и 21,9% среди пациентов 90 лет и старше. Ключевыми коморбидными факторами риска стали хроническая болезнь почек (летальность 23,2%), ишемическая болезнь сердца (19,7%) и сахарный диабет 2-го типа (18%). У 21% пациентов, преимущественно пожилого возраста, заболевание протекало атипично, без лихорадки. Стратифицированный анализ показал, что значимость конкретных факторов риска (химиотерапия, ишемическая болезнь сердца, хроническая болезнь почек) варьировала в разных возрастных группах.</p> <p><bold>Заключение.</bold> Пожилой возраст и коморбидность являются независимыми факторами риска тяжёлого течения COVID-19 и летальных исходов. Особого внимания требуют пациенты старше 75 лет с хроническими заболеваниями. Ранняя диагностика и персонализированный подход к лечению могут улучшить прогноз в данной группе.</p></trans-abstract><kwd-group xml:lang="en"><kwd>COVID-19</kwd><kwd>aged</kwd><kwd>comorbidity</kwd><kwd>mortality</kwd><kwd>chronic kidney disease</kwd><kwd>myocardial ischemia</kwd><kwd>diabetes mellitus, type 2</kwd><kwd>severe</kwd><kwd>risk factors</kwd></kwd-group><kwd-group xml:lang="ru"><kwd>COVID-19</kwd><kwd>пожилой возраст</kwd><kwd>коморбидность</kwd><kwd>летальность</kwd><kwd>хроническая болезнь почек</kwd><kwd>ишемическая болезнь сердца</kwd><kwd>сахарный диабет 2-го типа</kwd><kwd>тяжёлое течение</kwd><kwd>факторы риска</kwd></kwd-group><funding-group/></article-meta></front><body></body><back><ref-list><ref id="B1"><label>1.</label><mixed-citation>Samadizadeh S, Masoudi M, Rastegar M, et al. COVID-19: Why does disease severity vary among individuals? 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