Previous studies exploring the association between obesity and hypertension generally used a single baseline measurement of obesity. The effect of accumulating excess adiposity over time on the risk of hypertension is uncertain. This study aimed to examine the relationship between duration of obesity and incident hypertension using the Framingham Heart Study.
Two thousand, nine hundred and fifty-three participants aged 30–62 years without baseline hypertension were included. Blood pressure, height and weight were measured biennially. Duration of obesity was calculated. Time to incident hypertension was analysed using time-varying Cox proportional hazards regression with age as the time scale and censoring at time of death or end of follow-up.
Eighty percent of participants developed hypertension (median follow-up 15.9 years). A positive association between obesity duration and incident hypertension was observed in women. There was no longer an association when time-varying BMI was adjusted for (hazard ratio 0.95; (95% confidence interval 0.85–1.05)).
These findings suggest that the mechanism by which excess adiposity may increase blood pressure is primarily immediate and that long-term exposure to obesity does not further increase the risk of developing hypertension beyond the level of BMI attained.
aBaker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
bDepartment of Biostatistics and Population Health, Faculty of Public Health, University Muhammadiyah Aceh, Aceh, Indonesia
cDepartment of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Melbourne, Victoria
dSchool of Population Health, University of Queensland, Herston, Queensland, Australia
Correspondence to Stephanie K. Tanamas, Baker IDI Heart and Diabetes Institute, 99 Commercial Rd, Melbourne, VIC 3004, Australia Tel: +61 3 8532 1824; fax: +61 3 8532 1799; e-mail: Stephanie.Tanamas@bakeridi.edu.au
Received 21 April, 2014
Revised 3 October, 2014
Accepted 3 October, 2014