A Self-management Approach for Dietary Sodium Restriction in Patients With CKD: A Randomized Controlled Trial

Abstract

Rationale & objective: Patients with chronic kidney disease (CKD) are particularly sensitive to dietary sodium. We evaluated a self-management approach for dietary sodium restriction in patients with CKD.

Study design: Randomized controlled trial.

Setting & participants: Nephrology outpatient clinics in 4 Dutch hospitals. 99 adults with CKD stages 1 to 4 or a functioning (estimated glomerular filtration rate≥25mL/min/1.73m²) kidney transplant, hypertension, and sodium intake>130mmol/d.

Intervention: Routine care was compared with routine care plus a web-based self-management intervention including individual e-coaching and group meetings implemented over a 3-month intervention period, followed by e-coaching over a 6-month maintenance period.

Outcomes: Primary outcomes were sodium excretion after the 3-month intervention and after the 6-month maintenance period. Secondary outcomes were blood pressure, proteinuria, costs, quality of life, self-management skills, and barriers and facilitators for implementation.

Results: Baseline estimated glomerular filtration rate was 55.0±22.0mL/min/1.73m². During the intervention period, sodium excretion decreased in the intervention group from 188±8 (SE) to 148±8mmol/d (P<0.001), but did not change significantly in the control group. At 3 months, mean sodium excretion was 24.8 (95% CI, 0.1-49.6) mmol/d lower in the intervention group (P=0.049). At 3 months, systolic blood pressure (SBP) decreased in the intervention group from 140±3 to 132±3mm Hg (P<0.001), but was unchanged in the control group. Mean difference in SBP across groups was-4.7 (95% CI, -10.7 to 1.3) mm Hg (P=0.1). During the maintenance phase, sodium excretion increased in the intervention group, but remained lower than at baseline at 160±8mmol/d (P=0.01), while it decreased in the control group from 174±9 at the end of the intervention period to 154±9mmol/d (P=0.001). Consequently, no difference in sodium excretion between groups was observed after the maintenance phase. There was no difference in SBP between groups after the maintenance phase.

Limitations: Limited power, postrandomization loss to follow-up, Hawthorne effect, lack of dietary data, short-term follow-up.

Conclusions: A coaching intervention reduced sodium intake at 3 months. Efficacy during the maintenance phase was diminished, possibly due to inadvertent adoption of the intervention by the control group.

Funding: Grant funding from the Netherlands Organization for Health Research and Development and the Dutch Kidney Foundation.

Trial registration: Registered at ClinicalTrials.gov with study number NCT02132013.

Keywords: Sodium; behavioral intervention; blood pressure (BP); chronic kidney disease (CKD); co-creation; dietary modification; hypertension; lifestyle; modifiable risk factor; randomized controlled trial (RCT); self-regulation; sodium intake; transplantation.