Kidney stones are known for causing severe, often debilitating pain. They can disrupt daily life and frequently send people to the emergency room. In the United States, about 1 in 11 people will develop kidney stones, and nearly half of them will experience another episode later on.
A large new clinical trial led by the Urinary Stone Disease Research Network and coordinated by the Duke Clinical Research Institute set out to answer a key question: can a structured behavioral program help people drink enough fluids to prevent kidney stones from returning?
The findings, published recently in The Lancet, shed light on why preventing kidney stones remains difficult, even when people are motivated and receive ongoing support.
“The trial results show that despite the importance of high fluid intake to prevent stone recurrence, achieving and maintaining very high fluid intake is more challenging than we often assume for people with urinary stone disease,” said Charles Scales, M.D., corresponding and co-senior author of the paper and associate professor in the departments of Urology and Population Health Sciences at Duke University School of Medicine.
“The challenge of adherence likely contributes to the relatively high rate of stone recurrence in people with this chronic condition,” Scales said.
Smart Bottles and Coaching Still Fell Short
Participants in the study were randomly assigned to either standard care or a behavioral hydration program designed to increase fluid intake. The program included Bluetooth-enabled smart water bottles that tracked how much participants drank, along with personalized hydration goals (“fluid prescriptions”), reminder texts, financial incentives, and health coaching.
Each participant’s “fluid prescription” was calculated by comparing their usual urine output with the amount needed to reach a daily goal of at least 2.5 liters.
Although people in the program did increase how much they drank, and their average urine output rose, the improvement was not enough to significantly reduce the rate of symptomatic kidney stone recurrence across the entire group.
Largest Behavioral Study of Its Kind
The trial included 1,658 adolescents and adults from six major U.S. clinical centers (UT Southwestern Medical Center, Washington University in St. Louis, University of Pennsylvania/Children’s Hospital of Philadelphia, University of Washington, Mayo Clinic and Cleveland Clinic). Researchers followed participants for two years to monitor outcomes.
This study stands out because it directly measured whether kidney stones came back, rather than focusing only on fluid intake or urine levels. Researchers used regular surveys and imaging to determine if new stones formed or existing ones grew.
Why Staying Hydrated Is So Difficult
The results highlight how hard it can be for people to consistently drink large amounts of fluid every day, even when supported by technology and coaching. The findings suggest that a single hydration target may not work for everyone, since fluid needs vary depending on factors such as age, body size, lifestyle, and overall health.
“Across adolescents and adults, the study moves the field toward more precise prevention,” said Gregory E. Tasian, M.D., co-senior author and attending pediatric urologist in the Division of Urology and principal investigator of the trial at the Children’s Hospital of Philadelphia.
“Rather than asking every patient to meet the same fluid goal, we should determine who benefits from which targets, understand why adherence breaks down, and build interventions — behavioral and medical — that reliably reduce stone recurrence,” Tasian said.
Toward More Personalized Kidney Stone Prevention
Researchers say the findings point to the need for new approaches to prevention. These could include more individualized hydration goals, strategies to overcome barriers related to work and daily routines, and potential treatments that help keep minerals dissolved in the urine.
“Kidney stone disease is a chronic condition, punctuated by unpredictable, sometimes excruciatingly painful episodes that can disrupt work, sleep, productivity and life in general,” said Alana Desai, M.D., first author of the study and principal investigator at the Washington University in St. Louis study site.
“Most people would appreciate a simple means to reduce their chances of experiencing another event,” said Desai.
In addition to Scales, Tasian, and Desai study authors include Naim M. Maalouf, Jonathan D. Harper, Sri Sivalingam, John C. Lieske, H. Henry Lai, Peter P. Reese, Hunter Wessells, Hongqiu Yang, Hussein R. Al-Khalidi, and Ziya Kirkali.
The study, along with other research from the Urinary Stone Disease Research Network, was funded by the National Institute of Diabetes and Digestive and Kidney Diseases.
