Objective: To investigate how age modifies the relation between body mass and blood pressure.
Design: Community based cross-sectional study.
Subjects: 2865 residents aged 6 to 74 years (85.6% of the target population) in the town of Humboldt, Saskatchewan, Canada.
Measurements: Body mass index [weight (kg)/height (meters)2], and diastolic and systolic blood pressures.
Results: Among the subjects, 99.6% were of Caucasian origin. With both sexes, there was a stronger relation between body mass index and diastolic blood pressure in younger age groups than older age groups. In males, the increase in mean blood pressure for a 1-unit increase in body mass index (kg/m2) was 0.72, 0.72, 0.41 and 0.47 mm Hg in the 6-14, 15-34, 35-54 and 55-74 year age groups respectively. In females, the correspondent increase was 0.95, 0.57, 0.46 and 0.43 mm Hg. In females, age also modified the relation between body mass index and the prevalence of high blood pressure. The odds ratios for high blood pressure for a 1-unit increase in body mass index in females was 1.33, 1.21, 1.12 and 1.10 in the 6-14, 15-34, 35-54 and 55-74 year age groups.
Conclusion: Age significantly modifies the relations of body mass index with mean diastolic blood pressure in both sexes, and with the prevalence of high blood pressure in females. The relations are stronger in children and young adults than in older persons.