Short-, Medium-, and Long-term Weight Changes and All-Cause Mortality in Old Age: Findings From the National Survey of the Japanese Elderly

Abstract

Background: Recent studies, predominantly in Western populations, suggest that both weight loss and weight gain are associated with an increased mortality risk in old age. However, evidence of this association in older Asian populations remains sparse. This study aimed to examine the association between weight change and all-cause mortality in a nationally representative sample of community-dwelling older Japanese people.

Methods: Data were obtained from the National Survey of the Japanese Elderly, which included 4869 adults aged ≥60 years. Participants were followed for up to 30 years. We considered 3 indicators of weight change according to the follow-up interval: short-term (3 years), medium-term (6-7 years), and long-term (12-13 years). Weight change was classified as loss ≥ 5%, loss 2.5%-4.9%, stable (±2.4%), gain 2.5%-4.9%, and gain ≥ 5%. Cox proportional hazards models were used to calculate the relative mortality risk of each weight change category.

Results: Weight loss ≥ 5% for all intervals was associated with higher mortality than stable weight and the effects were largely similar across all 3 intervals (hazard ratio [95% confidence interval]: 1.36 [1.22-1.51] for short-term, 1.36 [1.22-1.51] for medium-term, and 1.31 [1.11-1.54] for long-term). A similar pattern of results was observed among the young-old and old-old, and among men and women. The effect of weight loss on higher mortality was greater among those with a lower body mass index at baseline.

Conclusions: These findings could inform clinical and public health approaches to body-weight management aimed at improving the health and survival of older adults, particularly in Asian populations.

Keywords: Epidemiology; Japan; Longevity; Obesity.

Figure 1.

Flow diagram of study participants of the National Survey of Japanese Elderly. a: We excluded the cohort surveyed in 1996 (Wave 4; n = 898), because they had no corresponding survey to calculate long-term weight change. b: The number of participants who responded to both the baseline and 3-year follow-up surveys. c: The number of participants who responded to both the baseline and 6- or 7-year follow-up surveys. d: The number of participants who responded to both the baseline and 12- or 13-year follow-up surveys.