{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,30]],"date-time":"2026-04-30T07:01:16Z","timestamp":1777532476259,"version":"3.51.4"},"reference-count":23,"publisher":"BMJ","issue":"12","content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Open"],"published-print":{"date-parts":[[2013,12]]},"abstract":"<jats:sec>\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>Fever of unknown origin (FUO) can be caused by many diseases, and varies depending on region and time period. Research on FUO in Japan has been limited to single medical institution or region, and no nationwide study has been conducted. We identified diseases that should be considered and useful diagnostic testing in patients with FUO.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Design<\/jats:title>\n                    <jats:p>A nationwide retrospective study.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Setting<\/jats:title>\n                    <jats:p>17 hospitals affiliated with the Japanese Society of Hospital General Medicine.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Participants<\/jats:title>\n                    <jats:p>This study included patients \u226518 years diagnosed with \u2018classical fever of unknown origin\u2019 (axillary temperature \u226538\u00b0C at least twice over a \u22653-week period without elucidation of a cause at three outpatient visits or during 3\u2005days of hospitalisation) between January and December 2011.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>A total of 121 patients with FUO were enrolled. The median age was 59\u2005years (range 19\u201394\u2005years). Causative diseases were infectious disease in 28 patients (23.1%), non-infectious inflammatory disease in 37 (30.6%), malignancy in 13 (10.7%), other in 15 (12.4%) and unknown in 28 (23.1%). The median interval from fever onset to evaluation at each hospital was 28\u2005days. The longest time required for diagnosis involved a case of familial Mediterranean fever. Tests performed included blood cultures in 86.8%, serum procalcitonin in 43.8% and positron emission tomography in 29.8% of patients.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>With the widespread use of CT, FUO due to deep-seated abscess or solid tumour is decreasing markedly. Owing to the influence of the ageing population, polymyalgia rheumatica was the most frequent cause (9 patients). Four patients had FUO associated with HIV\/AIDS, an important cause of FUO in Japan. In a relatively small number of cases, cause remained unclear. This may have been due to bias inherent in a retrospective study. This study identified diseases that should be considered in the differential diagnosis of FUO.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/bmjopen-2013-003971","type":"journal-article","created":{"date-parts":[[2013,12,20]],"date-time":"2013-12-20T22:59:12Z","timestamp":1387580352000},"page":"e003971","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":53,"title":["Diagnostic workup for fever of unknown origin: a multicenter collaborative retrospective study"],"prefix":"10.1136","volume":"3","author":[{"given":"Toshio","family":"Naito","sequence":"first","affiliation":[{"name":"Department of General Medicine, Juntendo University School of Medicine, Tokyo, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Masafumi","family":"Mizooka","sequence":"additional","affiliation":[{"name":"Department of General Internal Medicine, Hiroshima University Hospital, Hiroshima, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fujiko","family":"Mitsumoto","sequence":"additional","affiliation":[{"name":"Department of General Internal Medicine, Kyushu University Hospital, Fukuoka, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kenji","family":"Kanazawa","sequence":"additional","affiliation":[{"name":"Department of General Internal Medicine, Kobe University Hospital, Kobe, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Keito","family":"Torikai","sequence":"additional","affiliation":[{"name":"Department of General Internal Medicine, St Marianna University School of Medicine, Kawasaki, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shiro","family":"Ohno","sequence":"additional","affiliation":[{"name":"Department of General Medicine, Nara Medical University, Nara, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hiroyuki","family":"Morita","sequence":"additional","affiliation":[{"name":"Department of General Internal Medicine, Gifu University Graduate School of Medicine, Gifu, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Akira","family":"Ukimura","sequence":"additional","affiliation":[{"name":"Department of General Medicine, Osaka Medical College, Osaka, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nobuhiko","family":"Mishima","sequence":"additional","affiliation":[{"name":"Department of General Internal Medicine, Kainan Hospital, Aichi Prefectural Welfare Federation of Agricultural Cooperatives, Aichi, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fumio","family":"Otsuka","sequence":"additional","affiliation":[{"name":"Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yoshio","family":"Ohyama","sequence":"additional","affiliation":[{"name":"Department of General Medicine, Gunma University Graduate School of Medicine, Gunma, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Noriko","family":"Nara","sequence":"additional","affiliation":[{"name":"Department of General Medicine, Yokohama City University Medical Center, Yokohama, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kazunari","family":"Murakami","sequence":"additional","affiliation":[{"name":"Department of General Medicine, Faculty of Medicine, Oita University, Oita, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kouichi","family":"Mashiba","sequence":"additional","affiliation":[{"name":"Department of General Medicine, Kitakyushu Municipal Medical Center, Kitakyushu, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kenichiro","family":"Akazawa","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, Shonan Fujisawa Tokushukai Hospital, Fujisawa, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Koji","family":"Yamamoto","sequence":"additional","affiliation":[{"name":"Department of General Medicine, Sumitomo Hospital, Osaka, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shoichi","family":"Senda","sequence":"additional","affiliation":[{"name":"Department of Integrated Medicine, Kagawa University School of Medicine, Kagawa, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Masashi","family":"Yamanouchi","sequence":"additional","affiliation":[{"name":"Department of General Medicine, Juntendo University School of Medicine, Tokyo, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Susumu","family":"Tazuma","sequence":"additional","affiliation":[{"name":"Department of General Internal Medicine, Hiroshima University Hospital, Hiroshima, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jun","family":"Hayashi","sequence":"additional","affiliation":[{"name":"Department of General Internal Medicine, Kyushu University Hospital, Fukuoka, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"239","published-online":{"date-parts":[[2013,12,20]]},"reference":[{"key":"2025121422260215000_3.12.e003971.1","doi-asserted-by":"publisher","DOI":"10.1001\/jama.1930.02710450001001"},{"key":"2025121422260215000_3.12.e003971.2","doi-asserted-by":"publisher","DOI":"10.1097\/00005792-196102000-00001"},{"key":"2025121422260215000_3.12.e003971.3","doi-asserted-by":"publisher","DOI":"10.1097\/00005792-199711000-00002"},{"key":"2025121422260215000_3.12.e003971.4","doi-asserted-by":"publisher","DOI":"10.1258\/0956462961917564"},{"key":"2025121422260215000_3.12.e003971.5","doi-asserted-by":"publisher","DOI":"10.1080\/00365540600606564"},{"key":"2025121422260215000_3.12.e003971.6","doi-asserted-by":"publisher","DOI":"10.1097\/MD.0b013e31802fe858"},{"key":"2025121422260215000_3.12.e003971.7","doi-asserted-by":"crossref","first-page":"74","DOI":"10.2169\/internalmedicine.33.74","article-title":"Fever of unknown origin: a 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Fever of unknown origin: re-examined and redefined. Current clinical topics in infectious diseases. 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