Association of trajectory of body mass index with knee pain risk in Japanese middle-aged women in a prospective cohort study: the Japan Nurses' Health Study

Ayumi Ito; Kunihiko Hayashi; Shosuke Suzuki; Yuki Ideno; Takumi Kurabayashi; Toru Ogata; Atsushi Seichi; Masami Akai; Tsutomu Iwaya

doi:10.1136/bmjopen-2019-033853

Association of trajectory of body mass index with knee pain risk in Japanese middle-aged women in a prospective cohort study: the Japan Nurses' Health Study

BMJ Open. 2020 Feb 6;10(2):e033853. doi: 10.1136/bmjopen-2019-033853.

Authors

Ayumi Ito¹, Kunihiko Hayashi², Shosuke Suzuki^{3

4}, Yuki Ideno⁵, Takumi Kurabayashi⁶, Toru Ogata⁷, Atsushi Seichi⁸, Masami Akai⁹, Tsutomu Iwaya¹⁰

Affiliations

¹ Unit of International and Community Health Sciences, Graduate School of Health Sciences, Gunma University, Maebashi, Japan.
² Unit of International and Community Health Sciences, Graduate School of Health Sciences, Gunma University, Maebashi, Japan khayashi@gunma-u.ac.jp.
³ Faculty of Medicine, Gunma University, Maebashi, Japan.
⁴ Eco-Health Research Group, Isesaki, Japan.
⁵ Center for Mathematics and Data Science, Gunma University, Maebashi, Japan.
⁶ Department of Obstetrics & Gynecology, Niigata City General Hospital, Niigata, Japan.
⁷ Center for Sport Science and Health Promotion, Department of Rehabilitaion for the Movement Functions, National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Japan.
⁸ Department of Orthopaedic Surgery, Mitsui Memorial Hospital, Chiyoda-ku, Japan.
⁹ Graduate School, International University of Health and Welfare Kohokai Group, Minato-ku, Japan.
¹⁰ Nagano University of Health and Medicine, Nagano, Japan.

Abstract

Objectives: To investigate whether body mass index (BMI) trajectory, lifestyle and reproductive factors are associated with knee pain risk among middle-aged women.

Design: Prospective study of the Japan Nurses' Health Study (JNHS).

Setting: The JNHS investigates the health of female nurses in Japan. Biennial follow-up questionnaires are mailed to the participants.

Participants: The 7434 women aged over 40 years who responded to the 10-year self-administered follow-up questionnaire.

Primary outcome measure: 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.

Results: 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% CI) 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% CI) 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.

Conclusions: 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.

Keywords: epidemiology; knee; musculoskeletal disorders; public health.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Age Factors
Arthralgia / diagnosis*
Arthralgia / etiology
Body Mass Index*
Female
Follow-Up Studies
Humans
Japan
Knee Joint / physiopathology*
Middle Aged
Obesity / complications*
Obesity / physiopathology
Pain Measurement
Prospective Studies