Original Article

International Journal of Obesity (2009) 33, 490–496; doi:10.1038/ijo.2009.29; published online 17 February 2009

Increase in body mass index category since age 20 years and all-cause mortality: a prospective cohort study (the Ohsaki Study)

T Shimazu1,2, S Kuriyama1, K Ohmori-Matsuda1, N Kikuchi1, N Nakaya1 and I Tsuji1

  1. 1Division of Epidemiology, Department of Public Health and Forensic Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
  2. 2Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, Tokyo, Japan

Correspondence: Dr T Shimazu, Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan. E-mail: tshimazu@ncc.go.jp

Received 7 May 2008; Revised 8 January 2009; Accepted 25 January 2009; Published online 17 February 2009.

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Abstract

Background:

 

It is still unclear whether weight gain from early to late adulthood affects longevity. Furthermore, no study has addressed its association with all-cause and cause-specific mortality in an Asian population.

Methods:

 

We prospectively assessed the association between an increase in body mass index (BMI) category since age 20 years and risk of all-cause, cardiovascular disease (CVD) and cancer mortality. Self-reported information pertaining to BMI was collected from 38 080 Japanese men and women aged 40–79 years at study entry in 1994 after exclusion of participants with a BMI of <18.5 kg/m2 at age 20 years or at study entry. We defined six patterns of increase in BMI category at age 20 years and study entry: stable normal, overweight and obese, normal to overweight or obese, and overweight to obese.

Results:

 

During 7 years of follow-up, 2617 participants died. After adjustment for potential confounders, we observed a significantly increased risk of all-cause mortality for the pattern of normal weight at age 20 years and obese at study entry and of stable obese compared with stable normal in BMI category, the multivariate HRs (95% confidence interval (CI)) being 1.42 (1.08–1.88) and 2.26 (1.45–3.51), respectively. For the pattern of overweight at age 20 years and obese at study entry, the multivariate hazard ratio (95% CI) was 1.35 (0.92–1.98). In contrast, we did not observe an increased risk of all-cause mortality for normal weight at age 20 years and overweight at study entry, and stable overweight. For CVD and cancer mortality, these results were consistently observed.

Conclusion:

 

We observed an increased risk of all-cause mortality both among participants who had been persistently obese since early adulthood and participants who showed an increase in BMI category from normal to obese, compared with participants with a stable normal BMI category.

Keywords:

body mass index, weight change, mortality, prospective studies, Japan

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