- Click here for explanation of classification scheme.

A meta-analysis of controlled trials to determine the effect of a reduction in salt intake on blood pressure in children.

• Children 18 years old and younger
• Control group or control period
• Duration of salt reduction must have been for at least two weeks.

• Salt reduction combined with another intervention
• Participants were over 18 years of age
• Participants were taking anti-hypertensive drugs or other medications
• There was no control group or control period.

Recruitment

13 trials, 10 in children and adolescents and three in infants.

Design 

Meta-analysis

• 10 trials in children and adolescents, six were crossover design and four were parallel comparisons
• All but one was randomized
• All three trials in infants used parallel comparisons and two were randomized.

Blinding used

• 10 trials in children and adolescents:
  • One was double-blind
  • Seven were BP observer blind
  • Two did not report any blinding.
• Three trials in infants: 
  • One was double-blind
  • One was BP observer blind
  • One did not report any blinding.

Intervention

Salt reduction.

Statistical Analysis

• Fixed and random effects models
• I² and Q statistics
• Funnel plot asymmetry
• Egger's regression test
• Cochrane Collaboration Review Manager 4.2 software
• Statistical Package for the Social Sciences.

 

Timing of Measurements 

Various.

 Dependent Variables

• BP in children and adolescents:
  • Random-0 sphygmomanometer (three trials)
  • MTA-STAT (one trial)
  • Mercury sphygmomanometer (four trials)
  • Dinamap 845 devices connected to computer (two trials).
• BP in infants:
  • Shield BP Monitor (one trial)
  • Doppler Ultrasound device (one trial)
  • Dinamap 8100 Vital Signs Monitor (one trial). 

Independent Variables

• Na intake in children and adolescents:
  • 24-hour urinary Na (three trials)
  • Overnight urinary Na (three trials)
  • Spot urinary Na/creatinine ratio (one trial)
  • Spot urinary Na (one trial)
  • Food diary (one trial)
  • Erythrocyte Na concentration (one trial).
• Na intake in infants:
  • 24-hour urinary Na (one trial)
  • Spot urinary Na (one trial)
  • Spot urinary Na/creatinine ration (one trial).

Initial N

• Children and adolescents: 966 (sex not stated in some studies) 
• Infants: 551 (sex not stated in some studies).

Attrition (Final N)

Same as above.

Age

• Children and adolescents: Median 13 years (range eight to 16 years)
• Infants: Two trials started in newborns and one started at three months of age. Median duration was 20 weeks (range eight weeks to six months).

Location

• Children and adolescents
  • United States: Seven trials with N=822
  • Australia: Three trials with N=144.
• Infants
  • One trial each in the United States (N=27)
  • The Netherlands (N=466)
  • Israel (N=58).

• Children and Adolescents: All 10 trials
  • Median reduction in salt intake of 42% (interquartile range: 7% to 58%)
  • Net change in systolic BP was -1.17mm Hg (95% CI: -1.78 to -0.56; P<0.001)
  • Net change in diastolic BP was -1.29mm Hg (95% CI: -1.94 to -0.65; P<0.0001)
  • No significant heterogeneity for systolic BP (P=0.64, I²=0%)
  • No significant heterogeneity for diastolic BP (P=0.60, I²=0%).
• Children and Adolescents: Nine trials (the one non-randomized trial excluded)
  • Net change in systolic BP was -0.93mm Hg (95% CI: -1.66 to -0.20; P=0.01)
  • Net change in diastolic BP was -1.07mm Hg (95% CI: -2.00 to -0.14; P=0.02)
  • No significant heterogeneity for systolic BP (P=0.69, I²=0%)
  • No significant heterogeneity for diastolic BP (P=0.54, I²=0%).
• Children and Adolescents: Eight trials (two trials excluded with net changes in salt intake less than 5%)
  • Net change in systolic BP was -1.18mm Hg (95% CI: -1.82 to -0.55; P=0.0003)
  • Net change in diastolic BP was -1.20mm Hg (95% CI: -1.86 to -0.54; P=0.0003)
  • No significant heterogeneity for systolic BP (P=0.78, I²=0%)
  • No significant heterogeneity for diastolic BP (P=0.85, I²=0%).
• Infants: All three trials
  • Median reduction in salt intake of 54% (interquartile range: 51% to 79%)
  • Net change in systolic BP was -2.47mm Hg (95% CI: -4.00 to -0.94; P<0.01)
  • No significant heterogeneity for systolic BP (P=0.33, I²=8.7%).

 

This is the first meta-analysis of salt reduction in children, and it demonstrates that a modest reduction in salt intake causes immediate falls in blood pressure and, if continued, may well lessen the subsequent rise in blood pressure with age. This would result in major reductions in cardiovascular disease. These results in conjunction with other evidence provide strong support for a reduction in salt intake in children.