Kwok Man Ki, Lee Siu Yin, Leung Gabriel M, Schooling C Mary
School of Nursing and Health Sciences, Hong Kong Metropolitan University, Hong Kong, Hong Kong
School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, Hong Kong.
J Epidemiol Community Health. 2025 Aug 8;79(9):698-703. doi: 10.1136/jech-2025-223659.
Weight loss at older ages appears to be associated with higher mortality in Western and some East Asian countries, despite differences in the prevalence of obesity; whether it is relevant to China is unknown. We examined the association of body mass index (BMI) trajectories with all-cause mortality in older Chinese adults by sex and baseline age (65-69 years, 70+ years).
54 160 participants aged 65 or above from Hong Kong's Elderly Health Service Cohort with at least five BMI measurements were included. We identified distinct BMI trajectories using group-based trajectory modelling. We assessed the associations of BMI trajectories with mortality risk using a Cox model stratified by sex and age.
Compared with 'normal weight, stable', the 'low-normal weight, decreasing' had higher mortality risk in both sexes and age groups (eg, HR 1.43, 95% CI 1.24 to 1.66 in men aged 65-69 years). The 'overweight, stable' and 'obese, stable' had lower mortality risk, especially in men at older ages. However, the proportion in the 'low-normal weight, decreasing' was greater at 70+ years than at 65-69 years, while the proportion in the 'overweight, stable' and 'obese, stable' was lower in the older group.
Decreasing BMI is a likely symptom of ill health in older adults. Inconsistency between the risks and the proportion in each BMI trajectory group by age suggests the observed associations could be driven by changes in weight and preferential recruitment of survivors. Maintaining a healthy weight remains relevant at older ages.
在西方和一些东亚国家，尽管肥胖患病率存在差异，但老年人的体重减轻似乎与较高的死亡率相关；在中国是否如此尚不清楚。我们按性别和基线年龄（65 - 69岁、70岁及以上）研究了中国老年成年人的体重指数（BMI）轨迹与全因死亡率之间的关联。
纳入了香港老年健康服务队列中54160名年龄在65岁及以上且至少有五次BMI测量值的参与者。我们使用基于群体的轨迹模型确定了不同的BMI轨迹。我们使用按性别和年龄分层的Cox模型评估了BMI轨迹与死亡风险之间的关联。
与“体重正常，稳定”相比，“低正常体重，下降”在两个性别和年龄组中都有较高的死亡风险（例如，65 - 69岁男性中，风险比[HR]为1.43，95%置信区间[CI]为1.24至1.66）。“超重，稳定”和“肥胖，稳定”的死亡风险较低，尤其是在老年男性中。然而，“低正常体重，下降”在70岁及以上人群中的比例高于65 - 69岁人群，而“超重，稳定”和“肥胖，稳定”在老年组中的比例较低。
BMI下降可能是老年人健康不佳的一个症状。各BMI轨迹组的风险与比例在年龄上的不一致表明，观察到的关联可能是由体重变化和幸存者的优先招募所驱动。在老年阶段保持健康体重仍然很重要。
