Abstract 15512: Sodium Intake and All-Ccuse Mortality Over 20 Years of Follow-up
Introduction: While several studies suggest beneficial effects of lower sodium on cardiovascular disease, the relationship with total mortality remains controversial. Some have reported a J-shaped curve, but this may be due to poor quality exposures or confounding bias.
Methods: Two trials [Phase 1 (1987-90) and Phase 2 (1990-5) of the Trials of Hypertension Prevention] implemented sodium reduction interventions, over 18 months in Phase I and 36 months in Phase II. Multiple 24-hour urine specimens were collected from pre-hypertensive adults aged 30-54. In extended post-trial follow-up, deaths were ascertained through December 31, 2013 using the National Death Index. We assessed the relation of the randomized sodium interventions, as well as average sodium excretion among those not assigned to an active sodium intervention, with all-cause mortality through 23-26 years.
Results and Conclusions: Among 744 Phase I and 2382 Phase II participants randomized to sodium reduction or control, 251 deaths occurred, with a nonsignificant 15% lower risk among those in the active intervention (RR=0.85, 95% CI=0.66-1.09, p=0.19). Among 3021 usual care participants, 273 deaths occurred. There was a direct but nonsignificant association of average sodium excretion with mortality, with hazard ratios (HRs) of 0.73, 0.97, 1.00 (reference), and 1.03 (p-trend = 0.38) over <2300, 2300-<3600, 3600-<4800, and >=4800 mg/d after adjustment for trial variables, with an HR=1.10 per 1000 mg/day (95% CI = 0.98-1.24, p=0.09). There was no evidence of a J-shape or other nonlinear relation. The sodium/potassium ratio had an HR=1.11 per unit (95% CI = 0.99-1.25, p=0.07). While the results did not reach statistical significance, they are consistent with a benefit of sodium reduction on total mortality over a period of over 20 years. This study, with carefully characterized measures of sodium intake, found no inverse relation with total mortality, even at the lowest levels of sodium intake.
Author Disclosures: N.R. Cook: None. L.J. Appel: None. P.K. Whelton: None.
- © 2015 by American Heart Association, Inc.