{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T15:31:55Z","timestamp":1787671915447,"version":"build-2736575974"},"reference-count":49,"publisher":"Springer Science and Business Media LLC","issue":"1","license":[{"start":{"date-parts":[[2026,6,16]],"date-time":"2026-06-16T00:00:00Z","timestamp":1781568000000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"},{"start":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T00:00:00Z","timestamp":1787616000000},"content-version":"vor","delay-in-days":70,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"funder":[{"name":"This study was supported by a grant for Research on Emerging and Re-emerging Infectious Diseases from the Ministry of Health, Labour and Welfare, Japan","award":["grant numbers: 20HA2001 and 24HA2007"],"award-info":[{"award-number":["grant numbers: 20HA2001 and 24HA2007"]}]}],"content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["BMC Infect Dis"],"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Community-acquired pneumonia (CAP) remains a leading cause of death globally. Although childhood 13-valent pneumococcal conjugate vaccine (PCV13) has altered the epidemiology of pneumococcal disease in children, risk factors for CAP in older adults remain insufficiently explored. Additionally, few studies have compared risks between those aged 65\u201374 and \u2265\u200975 years. We evaluated risk factors for CAP in older Japanese adults by age.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>We conducted a secondary analysis of data from a multicenter, nationwide case-control study conducted between October 2016 and December 2019. Cases were individuals aged\u2009\u2265\u200965 years with CAP. Up to five controls per case were matched by sex, fiscal-year age, and visit date. Clinical and lifestyle data were questionnaire-based. Adjusted odds ratios (aORs) were calculated for participants overall and stratified by age (65\u201374 and \u2265\u200975 years) using conditional logistic regression.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Analysis included 142 cases and 596 controls. CAP risk was associated with living with children\u2009\u2264\u20096 years (aOR: 6.15, 95% confidence interval [CI]: 2.84\u201313.32), low body mass index (BMI) (&lt;\u200918.5\u00a0kg\/m\u00b2) (aOR: 1.78, 95% CI: 1.02\u20133.09), and impaired activities of daily living (ADL) (aOR: 2.44, 95% CI: 1.12\u20135.30). High BMI (\u2265\u200925.0\u00a0kg\/m\u00b2) was associated with a reduced risk (aOR: 0.55, 95% CI: 0.31\u20130.95). Among those aged 65\u201374 years, living with children\u2009\u2264\u20096 years (aOR: 4.89, 95% CI: 1.83\u201313.08) was a risk factor for CAP, whereas high BMI (aOR: 0.41, 95% CI: 0.18\u20130.89) and gastrointestinal disease (aOR: 0.19, 95% CI: 0.04\u20130.84) were associated with a reduced risk. Among those aged\u2009\u2265\u200975 years, chronic obstructive pulmonary disease (aOR: 3.59, 95% CI: 1.29\u20139.93), asthma (aOR: 2.99, 95% CI: 1.25\u20137.16), living with children\u2009\u2264\u20096 years (aOR: 11.62, 95% CI: 3.12\u201343.33), and impaired ADL (aOR: 2.90, 95% CI: 1.10\u20137.65) were risk factors for CAP. Only living with children\u2009\u2264\u20096 years was significant for pneumococcal CAP (aOR: 7.22, 95% CI: 1.23\u201342.34).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Living with children\u2009\u2264\u20096 years remains a major CAP risk factor in older adults after childhood PCV13 introduction. However, risk factors differ by age. Respiratory comorbidities and functional decline are dominant drivers of CAP in adults aged\u2009\u2265\u200975 years. Prevention strategies should consider age-specific dominant risk factors.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1186\/s12879-026-13820-7","type":"journal-article","created":{"date-parts":[[2026,6,16]],"date-time":"2026-06-16T11:09:41Z","timestamp":1781608181000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Risk factors for community-acquired pneumonia in older adults in Japan after the introduction of the childhood PCV13"],"prefix":"10.1186","volume":"26","author":[{"given":"Naoki","family":"Inoshima","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kei","family":"Nakashima","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kanzo","family":"Suzuki","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hirohiko","family":"Nagasaka","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Toshiaki","family":"Niwa","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chikara","family":"Nakahama","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Naoyuki","family":"Miyashita","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Satomi","family":"Iwamoto","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sakae","family":"Kan","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kyoko","family":"Kondo","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Satoko","family":"Ohfuji","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wakaba","family":"Fukushima","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2026,6,16]]},"reference":[{"issue":"15","key":"13820_CR1","doi-asserted-by":"publisher","first-page":"1282","DOI":"10.1001\/jama.2024.14796","volume":"332","author":"VM Vaughn","year":"2024","unstructured":"Vaughn VM, Dickson RP, Horowitz JK, Flanders SA. 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In addition, the study was approved by all participating institutions, Kameda Medical Center, and Nagoya City University. The research adhered to the principles outlined in the Declaration of Helsinki and the Japanese Ethical Guidelines for Medical and Health Research Involving Human Subjects. 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