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Non-linear dose-response relationship between body mass index and stroke risk in middle-aged and elderly Chinese men:
Gang Wei1, Feng Lin1, Changchun Cao2
1Department of Emergency, Hechi People's Hospital, Hechi, Guangxi Zhuang Autonomous Region, China.
Insights
Higher body mass index (BMI) increases stroke risk, particularly in Chinese men under 25.94 kg/m², where risk rises non-linearly. Maintaining a lower BMI is crucial for reducing stroke incidence in this group.
Area of Science:
- Epidemiology
- Public Health
- Cardiovascular Disease Research
Background:
- The association between body mass index (BMI) and stroke risk remains debated, necessitating further investigation in diverse populations.
- Previous studies have yielded conflicting results regarding the precise nature of the relationship between BMI and stroke incidence.
Purpose of the Study:
- To investigate the relationship between body mass index (BMI) and stroke risk in a middle-aged and elderly Chinese population.
- To identify potential non-linear associations and gender-specific differences in the BMI-stroke risk relationship.
Main Methods:
- Utilized four waves of data from the Chinese Health and Retirement Longitudinal Survey (CHARLS), encompassing 12,161 participants.
- Employed Cox proportional-hazards regression models with cubic spline functions and smooth curve fitting to analyze the non-linear relationship between BMI and stroke risk.
- Conducted a series of sensitivity analyses and stratified analyses by gender to validate findings.
Main Results:
- A positive association was observed between BMI and stroke risk (HR=1.025).
- A non-linear relationship was identified, with an inflection point at BMI 26.63 kg/m², indicating increased risk for BMIs below this threshold.
- Men exhibited a non-linear association with an inflection point at 25.94 kg/m², while women showed a linear association (HR=1.021 per 1 kg/m² increase).
Conclusions:
- A non-linear relationship exists between BMI and stroke risk, with a saturation effect observed in men.
- For men with BMI below 25.94 kg/m², stroke risk significantly increases with higher BMI.
- Controlling BMI below 25.94 kg/m² in men may substantially reduce stroke risk.
Objective:
Body mass index (BMI) and stroke risk have been linked, but these findings are still debated. This study investigated the relationship between BMI and stroke risk in a middle-aged and elderly Chinese population.
Methods:
This study used four waves of CHARLS data (2011, 2013, 2015, and 2018), including 12,161 participants. The CHARLS sample was obtained by multi-stage probability sampling and all participants were assessed by one-to-one interviews using a standardized questionnaire. We used a Cox proportional-hazards regression model to examine the relationship between BMI and stroke risk. We used Cox proportional hazards regression with cubic spline functions and smooth curve fitting to identify the non-linear relationship between them. A series of sensitivity analyses were also conducted.
Results:
The multivariate Cox proportional hazards regression model identified a positive association between BMI and stroke risk (HR=1.025, 95% CI: 1.010-1.040). We also found a non-linear relationship between BMI and stroke incidence, with an inflection point at 26.63 kg/m2 for BMI. Each 1 kg/m2 increase in BMI to the left of the inflection point was related to a 4.4% increase in stroke risk (HR=1.044, 95% CI: 1.019-1.069). We stratified individuals by gender to further investigate their association and found a particular non-linear relationship and saturation effect between BMI and stroke risk in men, with the inflection point at 25.94 kg/m2. Each 1 kg/m2 increase in BMI to the left of the inflection point was related to a 7.6% increase in stroke risk (HR=1.076, 95% CI 1.034-1.119). The association was linear in women, with each 1 kg/m2 increase in BMI associated with a 2.1% increase in stroke risk (HR=1.021, 95% CI 1.002, 1.040).
Conclusion:
In men, there was a specific non-linear association and saturation effect of BMI with stroke (inflection point of 25.94 kg/m2), while in women, there was none. When males had a BMI below 25.94 kg/m2, the risk of stroke was significantly and positively associated with BMI. By controlling BMI below 25.94 kg/m2 in men, a further decrease in BMI may promote a significant reduction in stroke risk.
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