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Effect of longer-term modest salt reduction on blood pressure

  1. Feng J He1,*,
  2. Jiafu Li2,
  3. Graham A MacGregor1

Editorial Group: Cochrane Hypertension Group

Published Online: 30 APR 2013

Assessed as up-to-date: 28 FEB 2013

DOI: 10.1002/14651858.CD004937.pub2


How to Cite

He FJ, Li J, MacGregor GA. Effect of longer-term modest salt reduction on blood pressure. Cochrane Database of Systematic Reviews 2013, Issue 4. Art. No.: CD004937. DOI: 10.1002/14651858.CD004937.pub2.

Author Information

  1. 1

    Queen Mary University of London, Wolfson Institute of Preventive Medicine, Barts and The London School of Medicine & Dentistry, London, UK

  2. 2

    Affiliated Hospital of LuZhou Medical College, Department of Cardiology, Luzhou, Sichuan, China

*Feng J He, Wolfson Institute of Preventive Medicine, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK. f.he@qmul.ac.uk.

Publication History

  1. Publication Status: New search for studies and content updated (conclusions changed)
  2. Published Online: 30 APR 2013

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Characteristics of included studies [ordered by year of study]
Parijs 1973

MethodsX


ParticipantsN=15
Age: 41 yr
Male: 43%
Hypertensive


InterventionsUNa: -98 mmol/24h
Duration: 4 wks


OutcomesSBP
DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Unclear riskNot stated

Incomplete outcome data (attrition bias)
All outcomes
Low riskProperly addressed, reasons for withdrawal were reported.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorHigh riskNot blinded to investigator

Blinding of the participantHigh riskNot blinded to participant

Blinding of the outcome assessorHigh riskNot blinded to outcome assessor

Morgan 1981 (F)

MethodsBP obs
P


ParticipantsIntervention: N=6

Control: N=6

Age: 38 yr

Male: 0%

Hypertensive

White: 100%


InterventionsUNa: -78 mmol/24h
Duration: 8 wks


OutcomesDBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Unclear riskNot stated

Incomplete outcome data (attrition bias)
All outcomes
Low riskAll participants who were randomised completed the study.

Selective reporting (reporting bias)Unclear riskDBP was reported and was included in our meta-analysis. SBP was also reported, however, it was reported in combination with another group of patients who were on BP treatment. Because our meta-analysis included participants who were not on any treatment and, in this trial, we could not separate the effect on salt reduction on SBP for individuals who were not on treatment, we did not include SBP in our pooled analysis.

Blinding of the investigatorHigh riskNot blinded to investigator

Blinding of the participantHigh riskNot blinded to participant

Blinding of the outcome assessorLow riskBlood pressure observer blind

Morgan 1981 (M)

MethodsBP obs
P


ParticipantsIntervention: N=6

Control: N=6

Age: 40 yr

Male: 100%

Hypertensive

White: 100%


InterventionsUNa: -98 mmol/24h
Duration: 8 wks


OutcomesDBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Unclear riskNot stated

Incomplete outcome data (attrition bias)
All outcomes
Low riskAll participants who were randomised completed the study.

Selective reporting (reporting bias)Unclear riskDBP was reported and was included in our meta-analysis. SBP was also reported, however, it was reported in combination with another group of patients who were on BP treatment. Because our meta-analysis included participants who were not on any treatment and, in this trial, we could not separate the effect on salt reduction on SBP for individuals who were not on treatment, we did not include SBP in our pooled analysis.

Blinding of the investigatorHigh riskNot blinded to investigator

Blinding of the participantHigh riskNot blinded to participant

Blinding of the outcome assessorLow riskBlood pressure observer blind

MacGregor 1982

MethodsDB
X


ParticipantsN=19

Age: 49 (30-66) yr

Male: 59%

Hypertensive

White: 63%; Black: 37%


InterventionsUNa: -76 mmol/24h
Duration: 4 wks


OutcomesSBP
DBP
PRA
Aldo


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of Slow Sodium and placebo tablets

Incomplete outcome data (attrition bias)
All outcomes
Low riskAll participants who were randomised completed the study.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

Watt 1983

MethodsDB
X


ParticipantsN=18

Age: 52 (31-64) yr

Male: 33%

Hypertensive

White: 100%


InterventionsUNa: -56 mmol/24h
Duration: 4 wks


OutcomesSBP
DBP
PRA


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of Slow Sodium and placebo tablets.

Incomplete outcome data (attrition bias)
All outcomes
Low riskProperly addressed, reasons for withdrawal were reported.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

Silman 1983

MethodsBP obs (RZ)
P


ParticipantsIntervention: N=10
Control: N=15
Age: 50-64 yr
Hypertensive


InterventionsUNa: -53 mmol/24h
Duration: 12 months


OutcomesSBP
DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Unclear riskNot stated

Incomplete outcome data (attrition bias)
All outcomes
Low riskProperly addressed, reasons for withdrawal were reported.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorHigh riskNot blinded to investigator

Blinding of the participantHigh riskNot blinded to participant

Blinding of the outcome assessorLow riskUse of random zero sphygmomanometer

Puska 1983 (H)

MethodsBP obs
P


ParticipantsIntervention: N=15

Control: N=19

Age: 30-50 yr

Hypertensive

White: 100%


InterventionsUNa: -117 mmol/24h
Duration: 6 wks


OutcomesSBP
DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Unclear riskNot stated

Incomplete outcome data (attrition bias)
All outcomes
Low riskAll participants who were randomised completed the study.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorHigh riskNot blinded to investigator

Blinding of the participantHigh riskNot blinded to participant

Blinding of the outcome assessorLow riskBlood pressure observer blind

Puska 1983 (N)

MethodsBP obs
P


ParticipantsIntervention: N=19

Control: N=19

Age: 30-50

Normotensive

White: 100%


InterventionsUNa: -117 mmol/24h
Duration: 6 wks


OutcomesSBP
DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Unclear riskNot stated

Incomplete outcome data (attrition bias)
All outcomes
Low riskAll participants who were randomised completed the study.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorHigh riskNot blinded to investigator

Blinding of the participantHigh riskNot blinded to participant

Blinding of the outcome assessorLow riskBlood pressure observer blinded

Richards 1984

MethodsBP obs (A)
X


ParticipantsN=12

Age: 19-52 yr

Male: 67%

Hypertensive

White: 100%


InterventionsUNa: -105 mmol/24h
Duration: 4-6 wks


OutcomesSBP
DBP
PRA
Aldo
Noradrenaline


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Unclear riskNot stated

Incomplete outcome data (attrition bias)
All outcomes
High riskNot stated

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorHigh riskNot blinded to investigator

Blinding of the participantHigh riskNot blinded to participant

Blinding of the outcome assessorLow riskUse of an automated version of the London School of Hygiene sphygmomanometer.

Erwteman 1984

MethodsBP obs (RZ)
P


ParticipantsIntervention: N=44

Control: N=50

Age: 46 (20-70) yr

Male: 62%

Hypertensive

White: 76%; Black: 24%


InterventionsUNa: -58 mmol/24h
Duration: 6 months


OutcomesSBP
DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Unclear riskNot stated

Incomplete outcome data (attrition bias)
All outcomes
Low riskProperly addressed, reasons for withdrawal were reported.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskAssignment to different salt intakes was single blind. Participants' dietary salt intake was supervised by a dietitian who was asked not to discuss participants' dietary assignment with the physician in charge or the technician.

Blinding of the participantHigh riskNot blinded to participant

Blinding of the outcome assessorLow riskOutcome assessor blind

Watt 1985 (HH)

MethodsDB
X


ParticipantsN=35

Age: 22 yr

Male: 37%

Normotensive

White: 100%


InterventionsUNa: -74 mmol/24h
Duration: 4 wks


OutcomesSBP
DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of Slow Sodium and placebo tablets.

Incomplete outcome data (attrition bias)
All outcomes
Unclear riskNot stated

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

Watt 1985 (LL)

MethodsDB
X


ParticipantsN=31

Age: 23 yr

Male: 45%

Normotensive

White: 100%


InterventionsUNa: -60 mmol/24h
Duration: 4 wks


OutcomesSBP
DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of Slow Sodium and placebo tablets.

Incomplete outcome data (attrition bias)
All outcomes
Unclear riskNot stated

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

Chalmers 1986

MethodsBP obs (A)
P


ParticipantsIntervention: N=48

Control: N=52

Age: 52 yr

Male: 85%

Hypertensive

All participants were white.


InterventionsUNa: -54 mmol/24h
Duration: 12 wks


OutcomesSBP
DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Unclear riskNot stated

Incomplete outcome data (attrition bias)
All outcomes
Low riskIntention to treat analysis was undertaken

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorHigh riskNot blinded to investigator

Blinding of the participantHigh riskNot blinded to participant

Blinding of the outcome assessorLow riskUse of automated blood pressure machine

Grobbee 1987

MethodsDB
X


ParticipantsN=40
Age: 18-28 yr
Male: 85%
Hypertensive


InterventionsUNa: -72 mmol/24h
Duration: 6 wks


OutcomesSBP
DBP
Noradrenaline
Chol


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of Slow Sodium and placebo tablets.

Incomplete outcome data (attrition bias)
All outcomes
Low riskProperly addressed, reasons for withdrawal were reported.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

ANHMRC 1989 (X)

MethodsDB
X


ParticipantsN=88

Age: 59 yr

Male: 83%

Hypertensive

All participants were white.


InterventionsUNa: -67 mmol/24h
Duration: 8 wks


OutcomesSBP
DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of Slow Sodium and placebo tablets

Incomplete outcome data (attrition bias)
All outcomes
Low riskIntention to treat analysis was undertaken

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

ANHMRC 1989 (P)

MethodsDB
P


ParticipantsIntervention: N=50

Control: N=53

Age: 58 yr

Male: 83%

Hypertensive

All participants were white.


InterventionsUNa: -71 mmol/24h
Duration: 8 wks


OutcomesSBP
DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of Slow Sodium and placebo tablets

Incomplete outcome data (attrition bias)
All outcomes
Low riskIntention to treat analysis was undertaken

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

MacGregor 1989

MethodsDB
X


ParticipantsN=20

Age: 56 (43-73) yr

Male: 55%

Hypertensive

White: 75%; Black: 25%


InterventionsUNa: -82 mmol/24h
Duration: 4 wks


OutcomesSBP
DBP
PRA
Aldo
Noradrenaline


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of Slow Sodium and placebo tablets

Incomplete outcome data (attrition bias)
All outcomes
Low riskAll participants who were randomised completed the study.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

Mascioli 1991

MethodsDB
X


ParticipantsN=48

Age: 52 yr

Male: 79%

Normotensive

White: 98%; Black: 2%


InterventionsUNa: -20 mmol/8h
Duration: 4 wks


OutcomesSBP
DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of sodium chloride and placebo capsules.

Incomplete outcome data (attrition bias)
All outcomes
Low riskProperly addressed, reasons for withdrawal were reported.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

Benetos 1992

MethodsDB
X


ParticipantsN=20

Age: 42 (22-55) yr

Male: 45%

Hypertensive

White: 100%


InterventionsUNa: -78 mmol/24h
Duration: 4 wks


OutcomesSBP
DBP
Noradrenaline


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of sodium chloride and placebo capsules.

Incomplete outcome data (attrition bias)
All outcomes
Low riskAll participants who were randomised completed the study.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

Cobiac 1992

MethodsDB
P


ParticipantsIntervention: N=26

Control: N=28

Age: 67 (60-80) yr

Male: 67%

Normotensive

White: 100%


InterventionsUNa: -73 mmol/24h
Duration: 4 wks


OutcomesSBP
DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of Slow Sodium and placebo tablets.

Incomplete outcome data (attrition bias)
All outcomes
Low riskIntention to treat analysis was undertaken

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

TOHP I 1992

MethodsBP obs (RZ)
P


ParticipantsIntervention: N=327

Control: N=417

Age: 43 (30-54) yr

Male: 71%

Normotensive

White: 77%; Black: 23%


InterventionsUNa: -44 mmol/24h
Duration: 18 months


OutcomesSBP
DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, central randomisation.

Incomplete outcome data (attrition bias)
All outcomes
Low riskIntention to treat analysis was undertaken

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorHigh riskNot blinded to investigator

Blinding of the participantHigh riskNot blinded to participant

Blinding of the outcome assessorLow riskUse of Hawksley random-zero sphygmomanometer.

Nestel 1993 (F)

MethodsDB
P


ParticipantsIntervention: N=15

Control: N=15

Age: 65 (60-79) yr

Male: 0%

Normotensive

White: 100%


InterventionsUNa: -94 mmol/24h
Duration: 6 wks


OutcomesSBP
DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of Slow Sodium and placebo tablets.

Incomplete outcome data (attrition bias)
All outcomes
Low riskProperly addressed, reasons for withdrawal were reported.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

Nestel 1993 (M)

MethodsDB
P


ParticipantsIntervention: N=17

Control: N=19

Age: 66 (60-79) yr

Male: 100%

Normotensive

White: 100%


InterventionsUNa: -76 mmol/24h
Duration: 6 wks


OutcomesSBP
DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of Slow Sodium and placebo tablets.

Incomplete outcome data (attrition bias)
All outcomes
Low riskProperly addressed, reasons for withdrawal were reported.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

Fotherby 1993

MethodsDB
X


ParticipantsN=17

Age: 73 (66-79) yr

Male: 24%

Hypertensive

White: 100%


InterventionsUNa: -79 mmol/24h
Duration: 5 wks


OutcomesSBP
DBP
PRA
Aldo


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of Slow Sodium and placebo tablets.

Incomplete outcome data (attrition bias)
All outcomes
Low riskProperly addressed, reason for exclusion was reported.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

Ruppert 1993

MethodsDB
X


ParticipantsN=25

Age: 47 (27-75) yr

Male: 40%

Normotensive

White: 100%


InterventionsUNa: -118 mmol/24h
Duration: 4 wks


OutcomesSBP
DBP
PRA
Noradrenaline
Chol
Trig
LDL
HDL


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of salt and placebo capsules

Incomplete outcome data (attrition bias)
All outcomes
Low riskAll participants who were randomised completed the study.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

Schorr 1996

MethodsDB
X


ParticipantsN=16

Age: 64 (60-72) yr

Male: 48%

Normotensive

White: 100%


InterventionsUNa: -71 mmol/24h
Duration: 4 wks


OutcomesSBP
DBP
PRA
Aldo
Chol
Trig
LDL
HDL


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of low sodium and high sodium chloride mineral water.

Incomplete outcome data (attrition bias)
All outcomes
Low riskProperly addressed, reasons for exclusion were reported.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

Cappuccio 1997 (H)

MethodsDB
X


ParticipantsN=29
Age: 67 (60-78) yr
Male: 51%
Hypertensive


InterventionsUNa: -87 mmol/24h
Duration: 4 wks


OutcomesSBP
DBP
PRA
Aldo


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of Slow Sodium and placebo tablets

Incomplete outcome data (attrition bias)
All outcomes
Low riskProperly addressed, reason for withdrawal was reported.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

Meland 1997

MethodsDB
X


ParticipantsN=16

Age: 50 yr

Male: 81%

Hypertensive

White: 100%


InterventionsUNa: -66 mmol/24h
Duration: 8 wks


OutcomesSBP
DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of salt and placebo capsules.

Incomplete outcome data (attrition bias)
All outcomes
Unclear riskOne patient dropped out during the trial and was replaced by another patient according to the same inclusion and randomisation procedures.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

TOHP II 1997

MethodsBP obs (RZ)
P


ParticipantsIntervention: N=515

Control: N=514

Age: 44 (30-54) yr

Male: 67%

Normotensive

White: 82%; Black: 18%


InterventionsUNa: -40 mmol/24h
Duration: 36 months


OutcomesSBP
DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, central randomisation.

Incomplete outcome data (attrition bias)
All outcomes
Low riskIntention to treat analysis was undertaken

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorHigh riskNot blinded to investigator

Blinding of the participantHigh riskNot blinded to participant

Blinding of the outcome assessorLow riskUse of Hawksley random-zero sphygmomanometer.

Cappuccio 1997

MethodsDB
X


ParticipantsN=47

Age: 67 (60-78) yr

Male: 51%

Hypertensive and normotensive

White: 89%; Black: 4%; Asian: 7%


InterventionsUNa: -87 mmol/24h
Duration: 4 wks


OutcomesSBP

DBP

PRA

Aldo

Cholesterol


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of Slow Sodium and placebo tablets

Incomplete outcome data (attrition bias)
All outcomes
Low riskProperly addressed, reason for withdrawal was reported.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

Cappuccio 1997 (N)

MethodsDB
X


ParticipantsN=18
Age: 67 (60-78) yr
Male: 51%
Normotensive


InterventionsUNa: -76 mmol/24h
Duration: 4 wks


OutcomesSBP
DBP
PRA
Aldo


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of Slow Sodium and placebo tablets

Incomplete outcome data (attrition bias)
All outcomes
Low riskProperly addressed, reason for withdrawal was reported.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

Sacks 2001 (H)

MethodsBP obs (RZ)
X


ParticipantsN=76
Age: 52 yr
Male: 39%
Hypertensive

White: 40%; Black: 60%


InterventionsUNa: -80 mmol/24h
Duration: 4 wks


OutcomesSBP
DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate

Incomplete outcome data (attrition bias)
All outcomes
Low riskIntention to treat analysis was undertaken.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskThe personnel involved in the collection of the outcome data were unaware of participants' diet assignment.

Blinding of the participantHigh riskNot blinded to participant

Blinding of the outcome assessorLow riskBlood pressure observer blinded

Sacks 2001 (N)

MethodsBP obs (RZ)
X


ParticipantsN=116

Age: 47 yr

Male: 50%

Normotensive

White: 46%; Black: 54%


InterventionsUNa: -75 mmol/24h
Duration: 4 wks


OutcomesSBP
DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate

Incomplete outcome data (attrition bias)
All outcomes
Low riskIntention to treat analysis was undertaken.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskThe personnel involved in the collection of the outcome data were unaware of participants' diet assignment.

Blinding of the participantHigh riskNot blinded to participant

Blinding of the outcome assessorLow riskBlood pressure observer blinded

Gates 2004

MethodsDB
X


ParticipantsN=12

Age: 64 yr

Male: 50%

Hypertensive

White: 100%


InterventionsUNa: -89 mmol/24h
Duration: 4 wks


OutcomesSBP
DBP
PRA
Chol
Trig
LDL
HDL
Noradrenaline


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of Slow Sodium and placebo tablets.

Incomplete outcome data (attrition bias)
All outcomes
Low riskAll participants who were randomised completed the study.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

Harsha 2004

MethodsBP obs (RZ)
X


ParticipantsN=193

Age: 49 yr

Male: 46%

Hypertensive and normotensive


InterventionsUNa: -77 mmol/24h

Duration: 4 wks


OutcomesCholesterol

LDL

HDL

Triglycerides


NotesThis paper reported the lipid data from the DASH-Na trial.


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate

Incomplete outcome data (attrition bias)
All outcomes
Low riskIntention to treat analysis was undertaken.

Selective reporting (reporting bias)Low riskAll lipid data from participants who gave fasting blood samples were analysed and reported.

Blinding of the investigatorLow riskThe personnel involved in the collection of the outcome data were unaware of participants' diet assignment.

Blinding of the participantHigh riskNot blinded to participant

Blinding of the outcome assessorLow riskThe personnel involved in the measurements of lipids were blinded to participants' dietary assignment.

Swift 2005

MethodsDB
X


ParticipantsN=40

Age: 50 yr

Male: 43%

Hypertensive

White: 0%; Black: 100%


InterventionsUNa: -78 mmol/24h
Duration: 4 wks


OutcomesSBP
DBP
PRA
Aldo


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of Slow Sodium and placebo tablets

Incomplete outcome data (attrition bias)
All outcomes
Low riskProperly addressed

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

Melander 2007

MethodsDB

X


ParticipantsN=39

Age: 53 (42-64) yr

Male: 51%

Hypertensive and normotensive

White: 100%


InterventionsUNa: -89 mmol/24h

Duration: 4 wks


OutcomesSBP

DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of salt and placebo capsules.

Incomplete outcome data (attrition bias)
All outcomes
Low riskProperly addressed, reasons for withdrawal were reported.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

Melander 2007 (H)

MethodsDB

X


ParticipantsN=19

Age: 53 (42-64) yr

Male: 53%

Hypertensive

White: 100%


InterventionsUNa: -93 mmol/24h

Duration: 4 wks


OutcomesSBP

DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of salt and placebo capsules.

Incomplete outcome data (attrition bias)
All outcomes
Low riskProperly addressed, reasons for withdrawal were reported.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

Melander 2007 (N)

MethodsDB

X


ParticipantsN=20

Age: 53 (42-64) yr

Male: 50%

Normotensive

White: 100%


InterventionsUNa: -85 mmol/24h

Duration: 4 wks


OutcomesSBP

DBP


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of salt and placebo capsules.

Incomplete outcome data (attrition bias)
All outcomes
Low riskProperly addressed, reasons for withdrawal were reported.

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

He 2009

MethodsDB

X


ParticipantsN=169

Age: 50 yr

Male: 67%

Hypertensive

White: 42%; Black: 41%: Asian: 17%


InterventionsUNa: -55 mmol/24h

Duration: 6 wks


OutcomesSBP

DBP

PRA

Aldo


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Allocation concealment (selection bias)Low riskAdequate, use of Slow Sodium and placebo tablets

Incomplete outcome data (attrition bias)
All outcomes
Low riskProperly addressed

Selective reporting (reporting bias)Low riskBoth SBP and DBP were reported.

Blinding of the investigatorLow riskDouble blind

Blinding of the participantLow riskDouble blind

Blinding of the outcome assessorLow riskOutcome assessor blind

 
Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion

Akita 2003Sub-study of DASH-Na trial (Sacks 2001)

Alam 1999Duration of salt reduction less than 4 weeks

Alli 1992Reduction in 24h urinary sodium less than 40 mmol

Ambrosioni 198224h urinary sodium not measured

Ames 2001With concomitant intervention

Andersson 1984With concomitant intervention

Andersson 1986Duration of salt reduction less than 4 weeks

Appel 2001Sub-study of TONE trial (Whelton 1998)

Appel 2003With concomitant intervention

Applegate 1992With concomitant intervention

Arroll 1995With concomitant intervention

Barba 2000Duration of salt reduction less than 4 weeks

Beard 1982With concomitant intervention

Beckmann 1995With concomitant intervention

Berglund 1989With concomitant intervention

Boero 2000Duration of salt reduction less than 4 weeks

Bompiani 1988With concomitant intervention

Bray 2004Sub-study of DASH-Na trial (Sacks 2001)

Bruun 1990Duration of salt reduction less than 4 weeks

Buckley 1994Duration of salt reduction less than 4 weeks

Bulpitt 1984With concomitant intervention

Burke 2005With concomitant intervention

Burke 2007With concomitant intervention

Burnier 1993Duration of salt reduction less than 4 weeks

Buyck 200924h urinary sodium not measured

Calabrese 1985Studies in children

Cappuccio 2006Reduction in 24h urinary sodium less than 40 mmol

Carney 1991With concomitant intervention

Charlton 2008With concomitant intervention

Chen 2008Duration of salt reduction less than 4 weeks

Chrysant 2000With concomitant intervention

Cook 2005Sub-study of TOHP II (TOHP II 1997)

Cook 2007Follow-up study of TOHP (TOHP 1992, TOHP II 1997)

Cook 2009Sub-study of TOHP (TOHP 1992, TOHP II 1997)

Cooper 1984Studies in children

Costa 198124h urinary sodium not measured

CSSS 200724h urinary sodium not measured

Cuzzola 2001Duration of salt reduction less than 4 weeks

Damasceno 1999Duration of salt reduction less than 4 weeks

Damasceno 2000Duration of salt reduction less than 4 weeks

Davis 1994With concomitant intervention

Davrath 1999Duration of salt reduction less than 4 weeks

Del Rio 1990With concomitant intervention

Del Rio 1993Duration of salt reduction less than 4 weeks

Delemarre 2000Studies in pregnant women

Dickinson 2009Duration of salt reduction less than 4 weeks

Dimsdale 1990Duration of salt reduction less than 4 weeks

Dodson 1984Study in patients with diabetes

Dodson 1989Study in patients with diabetes

Donovan 1993Duration of salt reduction less than 4 weeks

Dubbert 1995With concomitant intervention

Egan 1991Duration of salt reduction less than 4 weeks

Egan 1991(b)Duration of salt reduction less than 4 weeks

Ekinci 2009Study in patients with diabetes

Ekinci 2010Study in patients with diabetes

el Ashry 1987Duration of salt reduction less than 4 weeks

Elmer 1995With concomitant intervention

Elmer 2006With concomitant intervention

Fagerberg 1984With concomitant intervention

Fagerberg 1985With concomitant intervention

Feldman 1996Duration of salt reduction less than 4 weeks

Ferri 1993Duration of salt reduction less than 4 weeks

Ferri 1994Duration of salt reduction less than 4 weeks

Ferri 1996Duration of salt reduction less than 4 weeks

Fliser 1993(a)Duration of salt reduction less than 4 weeks

Fliser 1993(b)With concomitant intervention

Forrester 2005Duration of salt reduction less than 4 weeks

Fotherby 1997Sub-study of Fotherby 1993

Friberg 1990Duration of salt reduction less than 4 weeks

Fuchs 1987Duration of salt reduction less than 4 weeks

Gillies 1984With concomitant intervention

Gillum 1981Studies in children

Gomi 1998Duration of salt reduction less than 4 weeks

Gow 1992Duration of salt reduction less than 4 weeks

Grey 1996Duration of salt reduction less than 4 weeks

Hargreaves 1989Duration of salt reduction less than 4 weeks

Haythornthwaite 1992Duration of salt reduction less than 4 weeks

He 2000Follow-up study of TOHP I (TOHP I 1992)

He 2005(a)Sub-study of previous trials

He 2005(b)Sub-study of previous trials

He, J 2009Duration of salt reduction less than 4 weeks

Heagerty 1986Duration of salt reduction less than 4 weeks

Herlitz 1998Duration of salt reduction less than 4 weeks

Hofman 1983Studies in children

Houlihan 2002(a)Study in patients with diabetes

Houlihan 2002(b)Study in patients with diabetes

Howe 1991Studies in children

Howe1994With concomitant intervention

HPTRG 1990Reduction in 24-h urinary sodium less than 40 mmol

Hu 200924h urinary sodium not measured

Inoue 1996Duration of salt reduction less than 4 weeks

Ireland 2010Reduction in 24h urinary sodium less than 40 mmol

Ishimitsu 1996Duration of salt reduction less than 4 weeks

Iso 1996With concomitant intervention

Iwaoka 1994Duration of salt reduction less than 4 weeks

Jessani 2008Duration of salt reduction less than 4 weeks

Johnson 2001Duration of salt reduction less than 4 weeks

Jula 1990With concomitant intervention

Jula 1992(a)With concomitant intervention

Jula 1992(b)With concomitant intervention

Kawasaki 1998With concomitant intervention

Keven 2006With concomitant intervention

Kirpizidis 2005With concomitant intervention

Kojuri 2007Total 24h urinary sodium excretion not reported.

Koolen 1984 (a)Duration of salt reduction less than 4 weeks

Koolen 1984 (b)Duration of salt reduction less than 4 weeks

Koopman 1990 (a)With concomitant intervention

Koopman 1990 (b)With concomitant intervention

Koopman 1997With concomitant intervention

Kostis 2002With concomitant intervention

Kristinsson 1988With concomitant intervention

Kumanyika 1993Sub-study of TOHP I (TOHP I 1992)

Kumanyika 2005Sub-study of TOHP II

Kurtz 1987Duration of salt reduction less than 4 weeks

Lawton 1988Duration of salt reduction less than 4 weeks

Logan 1986Reduction in 24-h urinary sodium less than 40 mmol

Luft 1990Duration of salt reduction less than 4 weeks

Macgregor 1982Duration of salt reduction less than 4 weeks

MacGregor 1987With concomitant intervention

Mallamaci 1996Duration of salt reduction less than 4 weeks

Manunta 2001Duration of salt reduction less than 4 weeks

Mark 1975Duration of salt reduction less than 4 weeks

Mattila 2003With concomitant intervention

Maxwell 1984With concomitant intervention

McCarron 1997With concomitant intervention

Meland 2009With concomitant intervention

Miller 1988Studies in children

Miller 1997Duration of salt reduction less than 4 weeks

Morgan 1978Reduction in 24-h urinary sodium less than 40 mmol

Morgan 1988Duration of salt reduction less than 4 weeks

Mtabaji 1990Duration of salt reduction less than 4 weeks

Mu 2009With concomitant intervention

Mufunda 1992Duration of salt reduction less than 4 weeks

Muhlhauser 1996With concomitant intervention

Myers 1983Duration of salt reduction less than 4 weeks

Mülhauser 1996Study in patients with diabetes

Nakamura 200324h urinary sodium not measured

Nowson 1988With concomitant intervention

Nowson 2003With concomitant intervention

Nowson 2004With concomitant intervention

Nowson 2009With concomitant intervention

Omland 2001With concomitant intervention

Omvik 1995With concomitant intervention

Overlack 1993Duration of salt reduction less than 4 weeks

Overlack 1995Duration of salt reduction less than 4 weeks

Palacios 2004Study in children

Palmer 198924h urinary sodium not measured

Parfrey 198124h urinary sodium not measured

Parker 1990With concomitant intervention

Pechere-Bertschi 2008Duration of salt reduction less than 4 weeks

Pedersen 1986Duration of salt reduction less than 4 weeks

Perry 2003Duration of salt reduction less than 4 weeks

Petrie 1998Duration of salt reduction less than 4 weeks

Pimenta 2009Duration of salt reduction less than 4 weeks

Pogson 2009Blood pressure was not measured

Pomeranz 2002Studies in neonates

Redon 1995With concomitant intervention

Redon-Mas 1993With concomitant intervention

Richards 1986Duration of salt reduction less than 4 weeks

Ruilope 1992Duration of salt reduction less than 4 weeks

Ruilope 1993Duration of salt reduction less than 4 weeks

Ruppert 1991Duration of salt reduction less than 4 weeks

Ruppert 1994Duration of salt reduction less than 4 weeks

Salvetti 1988With concomitant intervention

Santello 1997Duration of salt reduction less than 4 weeks

Saptharishi 2009With concomitant intervention

Schmid 1990Duration of salt reduction less than 4 weeks

Schorr 1997(a)Duration of salt reduction less than 4 weeks

Schorr 1997(b)Duration of salt reduction less than 4 weeks

Sciarrone 1990With concomitant intervention

Sciarrone 1992With concomitant intervention

Sharma 1990Duration of salt reduction less than 4 weeks

Sharma 1991Duration of salt reduction less than 4 weeks

Sharma 1993Duration of salt reduction less than 4 weeks

Shore 1988Duration of salt reduction less than 4 weeks

Sinaiko 1993Studies in children

Singer 1991With concomitant intervention

Singer 1994Duration of salt reduction less than 4 weeks

Singer 1995With concomitant intervention

Skrabal 1980Duration of salt reduction less than 4 weeks

Skrabal 1981Duration of salt reduction less than 4 weeks

Skrabal 1984(a)Duration of salt reduction less than 4 weeks

Skrabal 1984(b)Duration of salt reduction less than 4 weeks

Skrabal 1985Duration of salt reduction less than 4 weeks

Staessen 1988Reduction in 24h urinary sodium less than 40 mmol

Starmans-Kool 2011Duration of salt reduction less than 4 weeks

Steegers 1991Studies in pregnant women

Sullivan 1980Duration of salt reduction less than 4 weeks

Suppa 1988With concomitant intervention

Suzuki 2000Duration of salt reduction less than 4 weeks

Takahashi 2006With concomitant intervention

Takashashi 2003With concomitant intervention

Teow 1985Duration of salt reduction less than 4 weeks

Thaler 1982With concomitant intervention

TMHRG 1991With concomitant intervention

Todd 2010With concomitant intervention

Todd 201224h urinary sodium not measured

Townsend 2007Duration of salt reduction less than 4 weeks

Tzemos 2008Duration of salt reduction less than 4 weeks

Uusitupa 1996With concomitant intervention

Uzu 1999Duration of salt reduction less than 4 weeks

Uzu 2009With concomitant intervention

Vaidya 2009Duration of salt reduction less than 4 weeks

van BergeLandry 2004Extreme change in salt intake, urinary sodium was changed from 309 to 24 mmol/24h

van Paassen 1996Duration of salt reduction less than 4 weeks

Vedovato 2004Study in patients with diabetes

Visser 2008Duration of salt reduction less than 4 weeks

Vollmer 2001Sub-study of the DASH-Na trial

Weder 1991Duration of salt reduction less than 4 weeks

Wedler 1992Duration of salt reduction less than 4 weeks

Weir 1995Duration of salt reduction less than 4 weeks

Weir 1997With concomitant intervention

Weir 1998With concomitant intervention

Weir 2001With concomitant intervention

Weir 2010With concomitant intervention

Whelton 1998With concomitant intervention

Whitten 1980Studies in children

Wing 1984With concomitant intervention

Wing 1998With concomitant intervention

Yamakoshi 2006With concomitant intervention

Yamamoto 1997With concomitant intervention

Yazici 2009With concomitant intervention

Zhao 2009Duration of salt reduction less than 4 weeks

Zoccali 1993Duration of salt reduction less than 4 weeks

Zoccali 1994(a)Duration of salt reduction less than 4 weeks

Zoccali 1994(b)Duration of salt reduction less than 4 weeks

Zoccali 1996Duration of salt reduction less than 4 weeks

 
Comparison 1. Change in BP

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Change in Systolic BP35Change in SBP (Random, 95% CI)-4.18 [-5.18, -3.18]

    1.1 Hypertensives
21Change in SBP (Random, 95% CI)-5.39 [-6.62, -4.15]

    1.2 Normotensives
14Change in SBP (Random, 95% CI)-2.42 [-3.56, -1.29]

 2 Change in Diastolic BP37Change in DBP (Random, 95% CI)-2.06 [-2.67, -1.45]

    2.1 Hypertensives
23Change in DBP (Random, 95% CI)-2.82 [-3.54, -2.11]

    2.2 Normotensives
14Change in DBP (Random, 95% CI)-1.00 [-1.85, -0.15]

 3 Change in Systolic BP by Ethnic Group31Change in SBP (Random, 95% CI)-4.41 [-5.39, -3.44]

    3.1 Hypertensive Whites
16Change in SBP (Random, 95% CI)-5.12 [-6.27, -3.96]

    3.2 Normotensive Whites
14Change in SBP (Random, 95% CI)-2.11 [-3.03, -1.19]

    3.3 Hypertensive Blacks
5Change in SBP (Random, 95% CI)-7.83 [-10.96, -4.71]

    3.4 Normotensive Blacks
3Change in SBP (Random, 95% CI)-4.02 [-7.44, -0.61]

 4 Change in Diastolic BP by Ethnic Group33Change in DBP (Random, 95% CI)-2.16 [-2.75, -1.57]

    4.1 Hypertensive Whites
18Change in DBP (Random, 95% CI)-2.66 [-3.37, -1.95]

    4.2 Normotensive Whites
14Change in DBP (Random, 95% CI)-0.88 [-1.68, -0.08]

    4.3 Hypertensive Blacks
5Change in DBP (Random, 95% CI)-4.08 [-5.90, -2.26]

    4.4 Normotensive Blacks
3Change in DBP (Random, 95% CI)-1.98 [-4.45, 0.49]

 5 Change in Systolic BP by Sex16Change in SBP (Random, 95% CI)-5.52 [-6.82, -4.23]

    5.1 Hypertensive Men
9Change in SBP (Random, 95% CI)-6.40 [-6.00, -4.80]

    5.2 Hypertensive Women
9Change in SBP (Random, 95% CI)-7.11 [-8.81, -5.41]

    5.3 Normotensive Men
6Change in SBP (Random, 95% CI)-3.39 [-5.63, -1.16]

    5.4 Normotensive Women
6Change in SBP (Random, 95% CI)-4.26 [-6.20, -2.31]

 6 Change in Diastolic BP by Sex18Change in DBP (Random, 95% CI)-2.87 [-3.54, -2.20]

    6.1 Hypertensive Men
10Change in DBP (Random, 95% CI)-3.96 [-5.47, -2.46]

    6.2 Hypertensive Women
10Change in DBP (Random, 95% CI)-3.41 [-4.29, -2.53]

    6.3 Normotensive Men
6Change in DBP (Random, 95% CI)-1.78 [-3.01, -0.55]

    6.4 Normotensive Women
6Change in DBP (Random, 95% CI)-2.18 [-2.95, -1.41]

 
Comparison 2. Change in hormone & lipid

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Change in PRA14Change in PRA (Random, 95% CI)0.26 [0.17, 0.36]

 2 Change in Aldosterone9Change in Aldosterone (Random, 95% CI)73.20 [44.92, 101.48]

 3 Change in Noradrenaline6Change in Noradrenaline (Random, 95% CI)31.67 [6.57, 56.77]

 4 Change in Adrenaline4Change in Adrenaline (Random, 95% CI)6.70 [-0.25, 13.64]

 5 Change in Cholesterol8Change in Cholesterol (Random, 95% CI)0.05 [-0.02, 0.11]

 6 Change in LDL5Change in LDL (Random, 95% CI)0.05 [-0.01, 0.12]

 7 Change in HDL6Change in HDL (Random, 95% CI)-0.02 [-0.06, 0.01]

 8 Change in Triglyceride6Change in Triglyceride (Random, 95% CI)0.04 [-0.02, 0.09]

 
Summary of findings for the main comparison. Change in systolic and diastolic blood pressure (SBP, DBP) from usual to reduced salt intake in hypertensive and normotensive individuals

 OutcomesNumber of

Trials
Number of

Participants
Median BP

on usual salt

(mmHg)
Mean change in BP* (mmHg)

with salt reduction [95% CI], P
Quality of the evidence

(GRADE)

 

All trials together

Duration of salt reduction:

Median: 4 weeks (range 4 weeks to 3 years)

Mean reduction in UNa: 75 mmol/24h

(equivalent to 4.4 g/d salt)
SBP333206141-4.18 [-5.18, -3.18], P<0.00001⊕⊕⊕⊕

High

DBP34323086-2.06 [-2.67, -1.45], P<0.00001⊕⊕⊕⊕

High

Hypertensives

Duration of salt reduction:

Median 5 weeks (range 4 weeks to 1 year)

Mean reduction in UNa: 75 mmol/24h

(equivalent to 4.4 g/d salt)

 
SBP21966148-5.39 [-6.62, -4.15], P<0.00001⊕⊕⊕⊕

High

DBP2299093-2.82 [-3.54, -2.11], P<0.00001⊕⊕⊕⊕

High

Normotensives

Duration of salt reduction:

Median 4 weeks (range 4 weeks to 3 years)

Mean reduction in UNa: 75 mmol/24h

(equivalent to 4.4 g/d salt)

 
SBP122240127-2.42 [-3.56, -1.29], P<0.0001⊕⊕⊕⊕

High

DBP12224077-1.00 [-1.85, -0.15], P=0.02⊕⊕⊕⊕

High

 * Negative value indicates that the effect favours reduced salt. UNa: urinary sodium.
 
Summary of findings 2. Change in 24h urinary sodium (UNa) and blood pressure (BP) in hypertensive and normotensive individuals by ethnic group

 Number of

Trials
Number of

Participants
Mean effect [95% CI] mmHgP value

Hypertensive whites    

    SBP (mmHg)16599-5.12 [-6.27, -3.96]<0.00001

    DBP (mmHg)17623-2.66 [-3.37, -1.95]<0.00001

    24h UNa (mmol)17623-77.44 [-85.22, -69.66]<0.00001

Hypertensive blacks    

    SBP (mmHg)5171-7.83 [-10.96, -4.71]<0.00001

    DBP (mmHg)5171-4.08 [-5.90, -2.26]<0.0001

    24h UNa (mmol)5171-66.87 [-82.79, -50.95]<0.00001

Hypertensive Asians    

    SBP (mmHg)129-5.41 [-9.27, -1.56]0.008

    DBP (mmHg)129-2.17 [-4.31, -0.03]0.047

    24h UNa (mmol)129-68.42 [-89.19, -47.64]<0.001

Normotensive whites    

    SBP (mmHg)121901-2.11 [-3.03, -1.19]<0.00001

    DBP (mmHg)121901-0.88 [-1.68, -0.08]0.03

    24h UNa (mmol)121901-76.45 [-89.52, -63.38]<0.00001

Normotensive blacks    

    SBP (mmHg)3412-4.02 [-7.44, -0.61]0.02

    DBP (mmHg)3412-1.98 [-4.45, 0.49]0.12

    24h UNa (mmol)3412-40.31 [-97.16, 16.55]0.16

 SBP: Systolic blood pressure. DBP: Diastolic blood pressure. UNa: Urinary sodium.
 
Summary of findings 3. Change in 24h urinary sodium (UNa) and blood pressure (BP) in hypertensive and normotensive individuals by sex

 Number of

Trials
Number of

Participants
Mean effect [95% CI] mmHgP value

Hypertensive men    

    SBP (mmHg)9227-6.40 [-8.00, -4.80]<0.00001

    DBP (mmHg)10239-3.96 [-5.47, -2.46]<0.00001

    24h UNa (mmol)10239-86.07 [-100.17, -71.97]<0.00001

Hypertensive women    

    SBP (mmHg)9181-7.11 [-8.81, -5.41]<0.00001

    DBP (mmHg)10193-3.41 [-4.29, -2.53]<0.00001

    24h UNa10193-69.56 [-77.56, -61.55]<0.00001

Normotensive men    

    SBP (mmHg)61391-3.39 [-5.63, -1.16]0.003

    DBP (mmHg)61391-1.78 [-3.01, -0.55]0.005

    24h UNa (mmol)61391-67.26 [-81.90, -52.62]<0.00001

Normotensive women    

    SBP (mmHg)6691-4.26 [-6.20, -2.31]<0.0001

    DBP (mmHg)6691-2.18 [-2.95, -1.41]<0.00001

    24h UNa (mmol)6691-62.98 [-88.59, -37.37]<0.00001

 SBP: Systolic blood pressure. DBP: Diastolic blood pressure. UNa: Urinary sodium.
 
Summary of findings 4. Change in plasma renin activity, aldosterone, noradrenaline and adrenaline

 Number of

Trials
Number of

Participants
Median value

on usual salt
Mean change

with salt reduction [95% CI]
P value

 

Plasma renin activity (ng/ml/hr)
144551.070.26 [0.17, 0.36]<0.00001

 

Aldosterone (pmol/l)
934029973.20 [44.92, 101.48]<0.00001

 

Noradrenaline (pg/ml)
612935131.67 [6.57, 56.77]0.01

 

Adrenaline (pg/ml)
484646.70 [-0.25, 13.64]0.06

 
Summary of findings 5. Change in plasma lipids

 Number of

Trials
Number of

Participants
Median value

on usual salt
Mean change

with salt reduction [95% CI]
P value

 

Cholesterol (mmol/l)
83655.30.05 [-0.02, 0.11]0.18

 

Low-density lipoprotein (LDL) (mmol/l)
52623.20.05 [-0.01, 0.12]0.11

 

How-density lipoprotein (HDL) (mmol/l)
62781.3-0.02 [-0.06, 0.01]0.19

 

Triglycerides (mmol/l)
63091.30.04 [-0.02, 0.09]0.22