{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,9]],"date-time":"2026-04-09T03:41:56Z","timestamp":1775706116615,"version":"3.50.1"},"reference-count":37,"publisher":"BMJ","issue":"2","license":[{"start":{"date-parts":[[2020,2,6]],"date-time":"2020-02-06T00:00:00Z","timestamp":1580947200000},"content-version":"unspecified","delay-in-days":5,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Open"],"accepted":{"date-parts":[[2020,1,9]]},"published-print":{"date-parts":[[2020,2]]},"abstract":"<jats:sec>\n                    <jats:title>Objectives<\/jats:title>\n                    <jats:p>To investigate whether body mass index (BMI) trajectory, lifestyle and reproductive factors are associated with knee pain risk among middle-aged women.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Design<\/jats:title>\n                    <jats:p>Prospective study of the Japan Nurses\u2019 Health Study (JNHS).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Setting<\/jats:title>\n                    <jats:p>The JNHS investigates the health of female nurses in Japan. Biennial follow-up questionnaires are mailed to the participants.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Participants<\/jats:title>\n                    <jats:p>The 7434 women aged over 40 years who responded to the 10-year self-administered follow-up questionnaire.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Primary outcome measure<\/jats:title>\n                    <jats:p>Self-reported knee pain at the 10-year follow-up was the primary outcome. We analysed BMI (normal or overweight) trajectory data from a baseline survey to the 10-year follow-up survey using group-based trajectory modelling. Exposure measurements were BMI trajectory, BMI at age 18 years, lifestyle variables and reproductive history.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>BMI trajectories from baseline to the 10-year follow-up were divided into four groups: remained normal, remained overweight, gained weight or lost weight. At the 10-year follow-up, 1281 women (17.2%) reported knee pain. Multivariable logistic regression analysis revealed that compared with the remained normal group, multivariable-adjusted ORs (95%\u2009CI) of knee pain were 1.93 (1.60 to 2.33) for the remained overweight group, 1.60 (1.23 to 2.08) for the gained weight group and 1.40 (0.88 to 2.21) for the lost weight group. The attributable risk percent (95%\u2009CI) of the remained overweight group was 48.1% (37.3% to 57.0%) compared with the reference group of remained normal. Alcohol intake at baseline was significantly associated with knee pain.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>The lost weight group had a lower risk than the remained overweight group and the gained weight group and did not carry statistically significant risks for knee pain. Weight reduction and maintaining a normal BMI in middle age was important for preventing knee pain in women.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/bmjopen-2019-033853","type":"journal-article","created":{"date-parts":[[2020,2,7]],"date-time":"2020-02-07T04:54:30Z","timestamp":1581051270000},"page":"e033853","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":11,"title":["Association of trajectory of body mass index with knee pain risk in Japanese middle-aged women in a prospective cohort study: the Japan Nurses\u2019 Health Study"],"prefix":"10.1136","volume":"10","author":[{"given":"Ayumi","family":"Ito","sequence":"first","affiliation":[{"name":"Unit of International and Community Health Sciences, Graduate School of Health Sciences, Gunma University, Maebashi, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4648-3936","authenticated-orcid":false,"given":"Kunihiko","family":"Hayashi","sequence":"additional","affiliation":[{"name":"Unit of International and Community Health Sciences, Graduate School of Health Sciences, Gunma University, Maebashi, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shosuke","family":"Suzuki","sequence":"additional","affiliation":[{"name":"Faculty of Medicine, Gunma University, Maebashi, Japan"},{"name":"Eco-Health Research Group, Isesaki, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yuki","family":"Ideno","sequence":"additional","affiliation":[{"name":"Center for Mathematics and Data Science, Gunma University, Maebashi, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Takumi","family":"Kurabayashi","sequence":"additional","affiliation":[{"name":"Department of Obstetrics & Gynecology, Niigata City General Hospital, Niigata, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Toru","family":"Ogata","sequence":"additional","affiliation":[{"name":"Center for Sport Science and Health Promotion, Department of Rehabilitaion for the Movement Functions, National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Atsushi","family":"Seichi","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Mitsui Memorial Hospital, Chiyoda-ku, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9145-7158","authenticated-orcid":false,"given":"Masami","family":"Akai","sequence":"additional","affiliation":[{"name":"Graduate School, International University of Health and Welfare Kohokai Group, Minato-ku, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tsutomu","family":"Iwaya","sequence":"additional","affiliation":[{"name":"Nagano University of Health and Medicine, Nagano, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"239","published-online":{"date-parts":[[2020,2,6]]},"reference":[{"key":"2025120523420405000_10.2.e033853.1","doi-asserted-by":"publisher","DOI":"10.3233\/WOR-2011-1136"},{"key":"2025120523420405000_10.2.e033853.2","doi-asserted-by":"publisher","DOI":"10.1136\/oemed-2013-101997"},{"key":"2025120523420405000_10.2.e033853.3","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pone.0039820","article-title":"The CUPID (cultural and psychosocial influences on disability) study: methods of data collection and characteristics of study sample","volume":"7","author":"Coggon","year":"2012","journal-title":"PLoS One"},{"key":"2025120523420405000_10.2.e033853.4","doi-asserted-by":"publisher","DOI":"10.1111\/j.1532-5415.1999.tb01563.x"},{"key":"2025120523420405000_10.2.e033853.5","doi-asserted-by":"publisher","DOI":"10.1093\/rheumatology\/kel243"},{"key":"2025120523420405000_10.2.e033853.6","doi-asserted-by":"crossref","first-page":"143","DOI":"10.1111\/obr.12110","article-title":"Does obesity affect knee cartilage? 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