JMIR Publications

ABSTRACT

Background:

Excessive salt intake is detrimental to the kidney. Nevertheless, salt restriction is often suboptimal in patients with CKD. Smartphone app-based interventions might help reduce salt intake.

Objective:

We investigated whether a hypertension-management app could reduce urinary sodium excretion in patients with CKD.

Methods:

This open-label randomized clinical trial included 101 patients with CKD who had a history of hypertension and estimated 24-hour urinary sodium excretion of ≥100 mmol. Patients in the intervention group used CureApp HT, a smartphone app designed to manage hypertension through lifestyle modifications and self-monitoring, particularly for salt restriction, plus lifestyle counseling by nephrologists. The control group received lifestyle counselling alone. The intervention period was 12 weeks. The primary outcome was the estimated 24-hour urinary sodium excretion calculated from spot urine samples using the Tanaka method. Key secondary outcomes included office blood pressure, brachial-ankle pulse wave velocity, urinary protein-to-creatinine ratio, and plasma brain natriuretic peptide.

Results:

A total of 101 patients were randomly assigned to the intervention group (n=51) or the control group (n=50). The median [25th, 75th percentile] app engagement rate was 96 [73, 99] %. The mean (standard deviation [SD]) baseline estimated glomerular filtration rate and 24-hour urinary sodium excretion were 38 (18) mL/min/1.73m2 and 145 (33) mmol, respectively. A higher proportion of patients in the intervention group reported that their salt intake behaviors had “significantly improved” or “somewhat improved” by the intervention than those in the control group (76% vs 38%; P<.001). However, the mean change in estimated 24-hour urinary sodium excretion during the intervention period did not differ significantly between groups (1.4 [95% confidence interval (CI), -12.0–14.7] mmol in the intervention group vs 2.5 [95% CI, -10.7–15.6] mmol in the control group: between-group difference, -1.1 [95% CI, -19.8–17.7] mmol; P=0.92). Secondary outcomes were not significantly different between groups.

Conclusions:

The smartphone app did not reduce salt intake in patients with CKD. Enhancing the intervention intensity may be necessary to effectively bridge the intention-behavior gap. Clinical Trial: jRCTs052220164