Long term effects of dietary sodium reduction on cardiovascular disease outcomes: observational follow-up of the trials of hypertension prevention (TOHP).
OBJECTIVE
To examine the effects of reduction in dietary sodium intake on cardiovascular events using data from two completed randomised trials, TOHP I and TOHP II.


METHODS
Long term follow-up assessed 10-15 years after the original trial.


METHODS
10 clinic sites in 1987-90 (TOHP I) and nine sites in 1990-5 (TOHP II). Central follow-up conducted by post and phone.


METHODS
Adults aged 30-54 years with prehypertension.


METHODS
Dietary sodium reduction, including comprehensive education and counselling on reducing intake, for 18 months (TOHP I) or 36-48 months (TOHP II).


METHODS
Cardiovascular disease (myocardial infarction, stroke, coronary revascularisation, or cardiovascular death).


RESULTS
744 participants in TOHP I and 2382 in TOHP II were randomised to a sodium reduction intervention or control. Net sodium reductions in the intervention groups were 44 mmol/24 h and 33 mmol/24 h, respectively. Vital status was obtained for all participants and follow-up information on morbidity was obtained from 2415 (77%), with 200 reporting a cardiovascular event. Risk of a cardiovascular event was 25% lower among those in the intervention group (relative risk 0.75, 95% confidence interval 0.57 to 0.99, P=0.04), adjusted for trial, clinic, age, race, and sex, and 30% lower after further adjustment for baseline sodium excretion and weight (0.70, 0.53 to 0.94), with similar results in each trial. In secondary analyses, 67 participants died (0.80, 0.51 to 1.26, P=0.34).


CONCLUSIONS
Sodium reduction, previously shown to lower blood pressure, may also reduce long term risk of cardiovascular events.
Cook
Nancy R
NR
Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA. ncook@rics.bwh.harvard.edu
Cutler
Jeffrey A
JA
Obarzanek
Eva
E
Buring
Julie E
JE
Rexrode
Kathryn M
KM
Kumanyika
Shiriki K
SK
Appel
Lawrence J
LJ
Whelton
Paul K
PK
D000328:Adult; D017677:Age Distribution; D016757:Death, Sudden, Cardiac / Q000209:etiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006973:Hypertension / Q000139:chemically induced / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000139:chemically induced; D009204:Myocardial Revascularization; D016032:Randomized Controlled Trials as Topic; D012307:Risk Factors; D017678:Sex Distribution; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage / Q000009:adverse effects*; D020521:Stroke / Q000139:chemically induced
D017673:Sodium Chloride, Dietary