A Hypertension Management App for Salt Restriction in Patients with CKD: The CureApp-CKD Trial

Background: Excessive salt intake is harmful to the kidney. In real-world clinical settings of patients with chronic kidney disease (CKD), however, salt restriction is often challenging. Mobile app-based interventions might be useful to reduce salt intake. Methods: This open-label, single-center, randomized controlled trial involved patients with CKD stages G1-G5 who had a history of hypertension and an estimated 24-hour urinary sodium excretion of ≥100 mmol. Patients randomized to an intervention group used CureApp HT, a hypertension-management app that enables individualized lifestyle modification, in addition to lifestyle counseling by nephrologists for 12 weeks. Patients in the control group received lifestyle counseling only. The primary outcome was a change in the estimated 24-hour urinary sodium excretion from baseline to 12 weeks. Key secondary outcomes were office blood pressure, brachial-ankle pulse wave velocity (baPWV), urinary protein-to-creatinine ratio (UPCR), brain natriuretic peptide (BNP), and body weight. This study was registered at the Japan Registry of Clinical Trials (jRCTs052220164). Results: A total of 101 patients were randomized, with 51 assigned to the intervention group and 50 to the control group. The mean (standard deviation) estimated 24-hour urinary sodium excretion at baseline was 145 (33) mmol. More patients in the intervention group reported that their salt intake behaviors had “significantly improved” or “somewhat improved” than those in the control group (76% vs. 40%; P<0.001). Despite the subjective improvement, there was no significant between-group difference in changes in the estimated 24-hour urinary sodium excretion (between-group difference, 0.9 mmol; 95% confidence interval [CI], -17.8 to 19.7; P=0.9). Secondary outcomes, including blood pressure levels, baPWV, UPCR, BNP, and body weight, were also not significantly different between groups. Conclusion: Further advancements in mobile app-based interventions might be needed to effectively suppress salt intake behaviors in patients with CKD.