Changes in the body mass index and blood pressure association across time: Evidence from multiple cross-sectional and cohort studies

David Bann,Shaun Scholes,Rebecca Hardy,Dara O'Neill

doi:10.1016/j.ypmed.2021.106825

David Bann, Shaun Scholes + Show 2 more

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https://doi.org/10.1016/j.ypmed.2021.106825

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Journal: Preventive Medicine	Publication Date: Sep 30, 2021
Citations: 4	License type: cc-by

Affiliation: University College London

Abstract

Although body mass index (BMI) is considered a key determinant of high blood pressure, its importance may differ over time and by age group. We utilised separate data sources to investigate temporal changes in this association: 23 independent (newly sampled), repeated cross-sectional studies (Health Survey for England (HSE)) at ≥25 years (1994–2018; N = 126,742); and three British birth cohorts at 43–46 years (born 1946, 1958, and 1970; N = 18,657). In HSE, associations were weaker in more recent years, with this trend most pronounced amongst older adults. After adjustment for sex, anti-hypertensive treatment and education, the mean difference in systolic blood pressure (SBP) per 1 kg/m2 increase in BMI amongst adults ≥55 years was 0.75 mmHg (95%CI: 0.60–0.90) in 1994, 0.66 mmHg (0.46–0.85) in 2003, and 0.53 mmHg (0.35–0.71) in 2018. In the 1958 and 1970 cohorts, BMI and SBP associations were of similar magnitude yet weaker in the 1946 cohort, potentially due to differences in blood pressure measurement device. Quantile regression analyses suggested that associations between BMI and SBP were present both below and above the hypertension threshold. A weaker association between BMI and blood pressure may partly offset the public health impacts of increasing obesity prevalence. However, despite sizable increases in use of antihypertensive medication, BMI remains positively associated with SBP in all ages. Our findings highlight the need to tackle non-medical factors such as population diet which influence both BMI and blood pressure, and the utility of using multiple datasets to obtain robust inferences on trends in risk factor-outcome associations across time.

Highlights

High body mass index (BMI) is an important modifiable determinant of high blood pressure, as evidenced by meta-analyses of observational studies[1] and weight-loss interventions.[2]
If the risks of rising BMI on raised blood pressure levels are increasing, the public health impacts of BMI may be greater than anticipated given the importance of high blood pressure for a range of cardiovascular[13] and neurological outcomes.[14 15]
Using data from 23 independent, repeated cross-sectional English datasets, we found that associations between BMI and systolic blood pressure (SBP) were weaker from 1994 to 2018; this trend was strongest in older (≥55 years) compared with younger (25-54 years) adults

Summary

Introduction

High body mass index (BMI) is an important modifiable determinant of high blood pressure, as evidenced by meta-analyses of observational studies[1] and weight-loss interventions.[2] While providing precise estimates of association between BMI and blood pressure, such studies have not elucidated whether this association has changed across time. Evidence from British birth cohorts born in 1946 and 1958 suggested an approximate doubling of the positive correlation between BMI and blood pressure in midlife from 1989 to 2003.3 Other studies have reported increasing strength of association, yet used hypertension as the sole outcome[4 5] (defined as elevated blood pressure or use of antihypertensive medication) and may be reflecting increases in treatment use.[6] In contrast, other studies have reported weakening of the association,[7 8] or reported no clear systematic change.[6]. If the risks of rising BMI on raised blood pressure levels are increasing, the public health impacts of BMI may be greater than anticipated given the importance of high blood pressure for a range of cardiovascular[13] and neurological outcomes.[14 15]

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