January 19, 2015
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Sodium intake not linked to mortality, incident CVD, incident HF in older adults

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In older adults, sodium intake as assessed by a food frequency questionnaire was not associated with 10-year mortality, incident CVD or incident HF, researchers found.

However, a nonstatistically significant elevated risk for death was observed in those consuming more than 2,300 mg/day of sodium.

The researchers analyzed 10-year follow-up data from 2,642 adults aged 71 to 80 years (mean age, 73.6 years; 51.2% women; 61.7% white) who were enrolled in a community-based prospective cohort study between April 1997 and July 1998.

Dietary sodium intake was assessed at baseline via a food frequency questionnaire. The researchers examined sodium intake as a continuous variable and a categorical variable and stratified participants into three groups: those with sodium intake less than 1,500 mg/day (11%), those with intake 1,500 mg/day to 2,300 mg/day (29.5%) and those with intake more than 2,300 mg/day (59.5%).

The primary outcomes were adjudicated death, incident CVD and incident HF at 10 years. The analysis of CVD included only the 1,981 participants without CVD at baseline.

At 10 years, 881 participants had died, 572 had developed CVD and 398 had developed HF, Andreas P. Kalogeropoulos, MD, MPH, PhD, from Emory Clinical Cardiovascular Research Institute, Emory University, and colleagues reported.

Mortality rates

When the researchers performed adjusted Cox proportional hazards regression models, they found that sodium intake was not associated with mortality (HR per 1 g=1.03; 95% CI, 0.98-1.09).

At 10 years, mortality rates were lower in those with sodium intake 1,500 mg/day to 2,300 mg/day (30.7%) compared with those with sodium intake less than 1,500 mg/day (33.8%) and those receiving more than 2,300 mg/day of sodium (35.2%), but the difference was not statistically significant, according to the researchers.

They also found that sodium intake of more than 2,300 mg/day was associated with nonsignificantly higher mortality in adjusted models compared with sodium intake 1,500 mg/day to 2,300 mg/day (HR=1.15; 95% CI, 0.99-1.35).

Indexing sodium intake with caloric intake and BMI did not change the results.

Kalogeropoulos and colleagues wrote that adjusted HRs for mortality were 1.2 (95% CI, 0.93-1.54) per milligram per kilocalorie and 1.11 (95% CI, 0.96-1.28) per 100 mg/kg/m2 of daily sodium intake.

CVD, HF data

When the researchers analyzed adjusted models accounting for the competing risk for death, they found that sodium intake was not associated with risk for CVD (<1,500 mg/day group, 28.5%; 1,500-2,300 mg/day group, 28.2%; >2,300 mg/day group, 29.7%; subHR per 1 g=1.03; 95% CI, 0.95-1.11) or HF (<1,500 mg/day group, 15.7%; 1,500-2,300 mg/day group, 14.3%; >2,300 mg/day group, 15.5%; subHR per 1 g=1; 95% CI, 0.92-1.08).

They did not observe any interactions with sex, race or hypertensive status for any outcome. In crude models, the elevated risk for death associated with sodium intake of more than 2,300 mg/day was driven by blacks, women and those without hypertension, but the differences were attenuated in adjusted models.

Previous research on the association between sodium intake and mortality has produced discrepant results, likely because of “differences in ranges of sodium intake, study populations, and methods of sodium assessment, as well as failure to explore nonlinear associations,” the researchers wrote.

However, very low sodium intake could be a problem in older adults. “Considering the special case of older adults, in whom comorbidities, inadequate caloric intake, and medication interactions are additional concerns with very low sodium intake, the effect of sodium restriction should probably be tested explicitly in this population before implementing a generalized recommendation for very low (<1,500 mg/day) sodium intake target. In the interim, a more conservative approach to sodium restriction (eg, targeting <2,300 mg/day) might be appropriate for older adults,” they wrote.

Disclosure: The study was supported in part by grants from the NIH. The researchers report no relevant financial disclosures.