Behavioral hydration program falls short in reducing kidney stone recurrence

A multicomponent behavioral intervention designed to increase fluid intake did not reduce symptomatic recurrence of urinary stones compared with guideline-based care, according to results from the Prevention of Urinary Stones with Hydration (PUSH) randomized clinical trial (NCT03244189) published in The Lancet.¹ Despite modest improvements in urine volume, recurrence rates remained similar between groups over 2 years of follow-up.

For clinicians, the results highlight the persistent gap between physiologic targets and real-world adherence, as well as the complexity of secondary prevention in stone disease.

“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 co-senior author Charles D. Scales Jr, MD, MSHS, FACS, associate professor in the departments of urology and population health sciences at Duke University School of Medicine in Durham, North Carolina.²

The randomized trial included 1658 adolescents and adults with a history of urinary stone disease and low baseline 24-hour urine volumes. Patients were enrolled across 6 US academic 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. According to the authors, the study population was “the largest to date for a stone prevention trial.”¹

Participants were assigned 1:1 to either a multicomponent behavioral intervention or standard guideline-concordant care. The intervention combined several adherence strategies, including individualized “fluid prescriptions,” financial incentives, health coaching, and patient-selected tools such as reminder text messages and Bluetooth-enabled smart water bottles. The goal was to achieve a urine output of at least 2.5 L per day.

The primary end point was symptomatic stone recurrence, defined as either stone passage or the need for procedural intervention during the 2-year follow-up period. Secondary outcomes included changes in 24-hour urine volume, radiographic recurrence or growth, urinary symptoms, and a composite stone outcome.

“The primary outcome of symptomatic stone recurrence is a noteworthy aspect of the PUSH study,” Scales noted in correspondence with Urology Times^®. “The investigators felt that it was very important to include an outcome that was clinically meaningful and important for patients, instead of simply looking at changes in urine output.”

The results showed that at a median follow-up of 738 days, symptomatic stone events occurred in 19% of patients in the intervention group and 20% in the control group (HR, 0.96; 95% CI, 0.77 to 1.20), indicating no statistically significant difference. Similarly, there were no significant differences in stone growth of at least 2 mm or new stones from baseline to the end-of-study imaging, or in the composite end point of symptomatic stone recurrence, new stone formation, or stone growth of at least 2 mm.

Although 24-hour urine volume increased in both groups, it was consistently higher in the intervention arm at 6, 12, 18, and 24 months. Urinary storage symptoms including frequency, urgency, and nocturia were more common in the intervention group at 6 months (P = .050) and 12 months (P = .014), but not at other time points.

No episodes of hyponatremia requiring hospitalization were reported, though asymptomatic hyponatremia occurred more frequently in the intervention group (1% vs <1%).

Notably, the investigators emphasized that these findings do not negate the role of hydration in stone prevention but instead point to the challenges of adherence to behavior change initiatives.

“It is very important to note that the study does NOT mean that fluid intake isn’t helpful for stone prevention; the control group received standard stone prevention care, including the recommendation to drink more fluids,” Scales commented in correspondence with Urology Times. “The reality of stone prevention is that drinking large amounts of fluids consistently is difficult for many patients.”

Scales also highlighted the potential of real-world barriers to adherence, noting, “Consider the perspective of a rideshare driver with kidney stone disease—where do you get water during the day? How easy is it to find a public bathroom? Do you choose to be dehydrated (and risk forming kidney stones) so you can make a living?”

Rather, the authors emphasized the importance of these findings for considering personalized approaches to nephrolithiasis care.

“Across adolescents and adults, the study moves the field toward more precise prevention,” said co-senior author Gregory E. Tasian, MD, MSc, MSCE, attending pediatric urologist in the Division of Urology and principal investigator of the trial at the Children’s Hospital of Philadelphia, in the news release on the findings.² “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.”

The authors highlighted several limitations of the study. Participants were recruited from tertiary academic centers, which may limit generalizability, and unmeasured factors such as additional fluid intake outside the smart bottle or dietary variation were not measured, although randomization likely mitigated some confounding. The 2-year follow-up may be relatively short, and the study was not designed to isolate the effects of individual intervention components; additionally, frequent contact with control participants and care within specialty stone clinics may have attenuated differences between groups.

Those considered, the findings suggest the need for collaboration to develop personalized, multifactorial strategies to prevent urinary stones.

Scales concluded, “Doctors, patients, and families should work together to personalize prevention plans that are feasible, which may include hydration, dietary changes, and potentially medications.”

REFERENCES

1. Desai AC, Maalouf NM, Harper JD, et al. Prevention of urinary stones with hydration: a randomised clinical trial of an adherence intervention. Lancet. 2026. 407;10534(P1171-1181). doi:10.1016/S0140-6736(25)02637-6

2. Largest Study of Its Kind Tests Hydration Strategy for Kidney Stones. News release. Duke Health. March 19, 2026. Accessed March 20, 2026. https://corporate.dukehealth.org/news/largest-study-its-kind-tests-hydration-strategy-kidney-stones