The role of salt intake and salt sensitivity in the management of hypertension in South Asian people with chronic kidney disease: a randomised controlled trial

Abstract

Background: The effectiveness of salt restriction to lower blood pressure (BP) in Bangladeshi patients with chronic kidney disease (CKD) is uncertain.

Objective: To test the hypothesis that a tailored intervention intended to reduce salt intake in addition to standard care will achieve a greater reduction in BP in UK Bangladeshi patients with CKD than standard care alone.

Design: A randomised parallel-group controlled trial conducted over a 6 month period.

Setting: A tertiary renal unit based in acute care hospital in East London.

Participants: 56 adult participants of Bangladeshi origin with CKD and BP >130/80 mm Hg or on antihypertensive medication.

Intervention: Participants were randomly allocated to receive a tailored low-salt diet or the standard low-salt advice. BP medication, physical activity and weight were monitored.

Main outcome measures: The primary outcome was change in ambulatory BP. Adherence to dietary advice was assessed by measurement of 24 h urinary salt excretion.

Results: Of 56 participants randomised, six withdrew at the start of the study. During the study, one intervention group participant died, one control group participant moved to Bangladesh. Data were available for the primary endpoint on 48 participants. Compared with control group the intervention urinary sodium excretion fell from 260 mmol/d to 103 mmol/d (-131 to -76, p<0.001) at 6 months and resulted in mean (95% CI) falls in 24 h systolic/diastolic BP of -8 mm Hg (-11 to -5)/2 (-4 to -2) both p<0.001.

Conclusions: A tailored intervention can achieve moderate salt restriction in patients with CKD, resulting in clinically meaningful falls in BP independent of hypertensive medication.

Trial registration: ClinicalTrials.gov NCT00702312.

Keywords: Renal Disease.

Figure 1

CONSORT flow chart of participant recruitment, allocation and assessment.

Figure 2

24 h urinary sodium excretion for intervention and control groups is shown as the mean difference with 95% CI in parenthesis. All differences are p<0.001. Control n=23, Intervention n=25.

Figure 3

Changes in daytime and night-time systolic blood pressure (SBP) and diastolic blood pressure (DBP). Mean values and changes with 95% CI. All differences are p<0.001. Control n=23, Intervention n=25.