Investigation of Non-Invasive Hydration Monitoring With Smart Water Bottle to Increase Fluid Intake in Patients With Nephrolithiasis and Low Urine Volume

Nephrolithiasis is one of the most common and costly diseases in medicine affecting nearly 10% of the population. It is also the most costly urologic disease with an estimated ten billion dollars per year in associated healthcare expenditures towards treating this condition. One of the biggest obstacles in controlling the growing incidence of the disease is better preventative care, especially considering that one third to one half of the patients who have a single stone event will have another stone within the next ten to fifteen years. Despite decades of research on preventative strategies to reduce stone recurrences there are only a handful of dietary and medical treatments with strong evidence supporting their use.

One of the cornerstones of kidney stone prevention is ensuring adequate fluid intake. Without adequate hydration, urinary volume is low which in turn increases super-saturation of all stone forming salts and increases the likelihood of stone formation. The best evidence supporting adequate fluid as a prevention strategy for stones comes from Borghi et al. who performed a 5 year randomized control study and found a 12% recurrence rate in the cohort of patients encouraged to achieve a goal of 2 liters (L) of urine per day compared to a 27% recurrence in the group who was not encouraged to increase fluid intake. Furthermore, the most recent guidelines by both the American Urological Association (AUA) and American College of Physicians (ACP) on medical management of kidney stones advocate a goal urine volume of 2.5 L for all stone formers.

Despite recommendations and evidence supporting its utility as an effective prevention mechanism for stone formers, achieving significant increases in hydration and subsequently urinary volumes remains a considerable clinical challenge. To date, adherence to increased fluid recommendations has been understudied with little data assessing patient compliance specifically for fluid. However, noncompliance with metabolic treatment of nephrolithiasis is common with estimates that only 50% of patients follow recommendations.These rates are similar to rates of noncompliance with recommended care in other chronic medical conditions as well including diabetes, chronic kidney disease, congestive heart failure, and metabolic syndrome.

Recently, mobile health technology has received much attention as a potential aide in helping improve compliance with medically indicated lifestyle and dietary treatments. Early studies using "smart technology" and mobile health applications have shown that implementation of such strategies can not only be beneficial in improving compliance, but also have the potential to lead to sustainable behavioral change. To date, there are no studies looking at mobile health technology as it applies to increasing fluid intake, particularly among stone formers.

Recently, a novel "smart" water bottle called "HidrateSpark" (www.hidratespark.com) developed by researchers at the University of Minnesota has been developed for use as a noninvasive fluid intake monitoring system. The device uses capacitive touch sensing via a sensor extending from the lid to the base, which calculates volume measurements by detecting changes in water levels. Data from the bottle is sent wirelessly to users' smartphones through an application.