A Randomized Trial of a Low-Fat Diet Intervention on Blood Pressure and Hypertension: Tertiary Analysis of the WHI Dietary Modification Trial

• Published in: American journal of hypertension 2016-08, Vol.29 (8), p.959-968
• Main Authors: Allison, Matthew A., Aragaki, Aaron K., Ray, Roberta M., Margolis, Karen L., Beresford, Shirley A.A., Kuller, Lewis, Jo O’Sullivan, Mary, Wassertheil-Smoller, Sylvia, Van Horn, Linda
• Format: Article
• Language: English
• Subjects: Aged; Blood Pressure; Diet, Fat-Restricted; Female; Humans; Hypertension - diet therapy; Kaplan-Meier Estimate; Middle Aged; Original; Therapeutics; Women's Health
• ISSN: 0895-7061; 1941-7225
• DOI: 10.1093/ajh/hpv196

BACKGROUND This post hoc analysis determined if the Women’s Health Initiative (WHI) Diet Modification intervention (DM-I) resulted in a significantly different rate of incident hypertension (HTN), as well as longitudinal changes in blood pressure. METHODS Participants were 48,835 postmenopausal women aged 50–79 years who were randomly assigned to either the intervention or comparison group. HTN was defined as self-report of treated HTN collected semiannually or blood pressure ≥140/90mm Hg at one of the annual follow-up clinic visits. RESULTS After a mean follow-up of 8.3 years, and among those who did not have HTN at baseline (n = 31,146), there were 16,174 (51.9%) HTN cases and those assigned to the intervention group had a 4% lower overall risk of developing incident HTN (hazard ratio (HR): 0.96, 95% confidence interval (CI): 0.93–0.99). Although the risk of HTN was lower in the DM-I group in the first few years, the HR became greater than 1 after year 5 (P-trend < 0.01). Similarly, randomization to the DM-I arm resulted in a small but significantly lower average systolic blood pressure (SBP) at 1 year of follow-up (−0.66mm Hg, 0.44–0.89) that increased over the following 8 years (0.16mm Hg/year, 0.11–0.21), such that any early benefit was eliminated by year 5 and a minimal deleterious effect emerged by year 7. CONCLUSION Randomization to an intensive behavioral dietary modification program aimed at a lower total fat intake is not associated with sustained reductions in blood pressure or risk of HTN in postmenopausal women. CLINICAL TRIAL REGISTRATION url http://www.clinicaltrials.gov, unique identifier nct00000611