Dietary Sodium Content, Mortality, and Risk for Cardiovascular Events in Older Adults: The Health, Aging, and Body Composition (Health ABC) Study | Journal Scan
What is the association between dietary sodium intake and mortality, incident cardiovascular disease (CVD), and incident heart failure (HF) in older adults?
The authors analyzed 10-year follow-up data from 2,642 older adults (age range, 71-80 years) participating in a community-based, prospective cohort study between April 1, 1997, and July 31, 1998 (the Health ABC study). Dietary sodium intake at baseline was assessed by a food frequency questionnaire. The sodium intake was assessed as a continuous variable and as a categorical variable at the following levels: <1500 mg/d [11.0%]), 1500-2300 mg/d [29.5%]), and >2300 mg/d [59.5%]. Primary outcome was the adjudicated death, incident CVD, and incident HF. Analysis of incident CVD was restricted to 1,981 participants without prevalent CVD at baseline.
The mean age was 73.6 (2.9) years, 51.2% were female, and 61.7% were white. More sodium was consumed by men than women (median 2850 mg/d vs. 2320 mg/d; p < 0.001). Whites and diabetics consumed more sodium, whereas participants with hypertension had lower intake. Greater sodium intake was associated with higher creatinine levels, but lower cholesterol levels. After 10 years, 33% of participants died, 29% developed CVD, and 15% developed HF. In adjusted Cox proportional hazards regression models, sodium intake was not associated with mortality (hazard ratio [HR] per 1 g, 1.03). Ten-year mortality was nonsignificantly lower in the group receiving 1500-2300 mg/d (30.7%) than in the group receiving <1500 mg/d (33.8%) and the group receiving >2300 mg/d (35.2%) (p = 0.07). Sodium intake of >2300 mg/d was associated with a nonsignificantly higher mortality in adjusted models (HR vs. 1500-2300 mg/d, 1.15; p = 0.07), driven primarily by women and blacks. Indexing sodium intake for caloric intake and body mass index did not affect the results. In adjusted models accounting for the competing risk for death, sodium intake was not associated with risk for CVD or HF. No consistent interactions with sex, race, or hypertensive status were observed for any outcome.
In older adults, food frequency questionnaire–assessed sodium intake was not associated with 10-year mortality, incident CVD, or incident HF, and consuming >2300 mg/d of sodium was associated with nonsignificantly higher mortality in adjusted models.
Excess dietary sodium intake is associated with risk factors for CVD and HF in persons with hypertension, renal function, left ventricular hypertrophy, and increased arterial stiffness. In contrast, less dietary sodium may unfavorably modulate insulin resistance, lipid levels, and neurohormonal activity factors that predispose to CVD and HF. In fact, a meta-analysis suggests there is a J-shaped or U-shaped association between dietary sodium intake and outcomes. Among the concerns of the generalizability of the Health ABC study are the relatively small size, ages 71-80 years old, long duration, and sodium intake was assessed with a food frequency questionnaire rather than 24-hour urinary excretion, which may have underestimated intake.
Keywords: Cardiovascular Diseases, Heart Failure, Cohort Studies, Hypertension, Surveys and Questionnaires, Risk, Sodium, Sodium, Dietary, Diabetes Mellitus, Creatinine
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