A Randomized Trial Evaluating the Use of a Smart Water Bottle to Increase Fluid Intake in Stone Formers

Objective: The aim of this study is to evaluate if the use of a smart water bottle improves urine volume in stone forming patients. Methods: Adults with nephrolithiasis and low urine volume (<1.5 L) documented on a 24-hour urinalysis (24 hr U) were randomized to receive either standard dietary recommendations to increase fluid intake (DR arm), or DR and a smart water bottle (HidrateSpark®; Hydrate Inc., Minneapolis, MN) that recorded fluid intake, synced to the user's smartphone, and provided reminders to drink (SB arm). Participants completed baseline surveys assessing barriers to hydration. They then repeated a 24 hr U and survey at 6 and 12 weeks, respectively. Results: Eighty-five subjects (44 DR, 41 SB) were enrolled. The main baseline factor limiting fluid intake was not remembering to drink (60%). Follow-up 24 hr Us were available for 51 patients. The mean increase in volume was greater in the SB arm (1.37 L, 95% confidence interval −0.51 to 3.25) than the DR arm (0.79 L, 95% confidence interval −1.15 to 2.73) (P = .04). A smaller percentage of subjects in the SB arm reported not remembering to drink as the main factor limiting fluid intake in the follow-up questionnaire compared to baseline (45.4% vs. 68.4%, P < .05). This was not true for the DR arm (40.0% vs. 51.2%, P = .13). Conclusions: Difficulty remembering to drink is a barrier to achieving sufficient fluid intake in stone formers. The use of a smart bottle was associated with greater increases in 24 hr U volumes and less difficulty remembering to drink.