Efficacy Trial of a Mobile Application for Fluid Intake Management in Patients Receiving Chronic Hemodialysis Therapy

Rationale & Objective Increased interdialytic weight gain (IDWG) is associated with increased morbidity and mortality in patients receiving chronic hemodialysis. We evaluated the efficacy of a smartphone-based application designed to support reductions in interdialytic fluid intake. Study Design Pre-post intervention study. Setting & Participants : Adult patients receiving chronic hemodialysis with mean IDWG >3.5% over a 3-month period were recruited from outpatient hemodialysis units in central North Carolina, United States. Intervention Participants were trained to use a smartphone-based application that allowed recording fluid intake and incorporated behavioral support features (e.g. goal setting, prompts, feedback). The patients were asked to use the app daily during the 8-week active phase of the trial. Outcomes The primary study outcome was the change in mean IDWG from baseline (before app usage) to the 8-week active phase. Secondary outcomes included app safety and usage. IDWG was also assessed during a 6-month passive phase to ascertain for possible long-term behavioral changes. Results Twenty-three patients completed the 8-week active phase and provided app data. Compared to baseline, mean IDWG for the 3-day interdialytic interval decreased by -0.52±0.24 pounds (p=0.032) during the active phase and -0.86±0.96 pounds (p<0.01) during the passive phase. No safety concerns (defined as >50% increase in IDWG) were observed. During the active phase, app was used on ≥80% of the days by 65% of participants and daily by 26% of participants. Reductions in IDWG were sustained during the passive phase. Correlation between app-recorded fluid intake and IDWG were weak and not statistically significant. Limitations This uncontrolled pre-post study was subject to selection bias toward more technologically literate and adherent participants, did not meet recruitment targets and lacked urine output data. Conclusions Use of a smartphone-based app designed to support fluid intake restriction was feasible and associated with sustained reductions in IDWG among patients receiving chronic hemodialysis, without safety concerns. Plain-Language Summary Excessive weight gains between hemodialysis sessions increase the risk of hospitalization and death. We developed a smartphone app that allows patients to record their fluid intake on a daily basis. The app also provides practical tips to help limit fluid intake and grants digital rewards when goals are met. We found that, on average, patients gained less weight between dialysis sessions while using the app compared to the period before they used it. These results suggest that smartphones apps that combine fluid intake tracking with behavioral support may help patients better control their fluid intake between dialysis sessions.