An interventional study of Fluid prescription and Financial incentive in Urinary Stones, sponsored by Duke University. Completed at 8 sites in United States. Open to participants aged 12 Years and older. Per ClinicalTrials.gov, last updated 2026-06-25.
Sponsored by Duke University · Not applicable, Interventional, and Prevention
A randomized clinical trial to investigate the impact of increased fluid intake and increased urine output on the recurrence rate of urinary stone disease (USD) in adults and children. The primary aim of the trial is to determine whether a multi-component program of behavioral interventions to increase fluid intake will result in reduced risk of stone disease progression over a 2-year period.
This is a two arm randomized controlled trial that incorporates pragmatic features, an adaptable intervention, patient choice, and remote monitoring of fluid intake through a "smart" water bottle. The study period is 24 months and will enroll approximately 1642 participants. Randomization will be stratified within a study site by age (adult vs. adolescent) and first time vs. recurrent stone former.
Intervention and control arm study participants will receive a smart water bottle that records daily fluid consumption, usual care including guideline-based recommendations of adequate fluid intake to decrease kidney stone recurrence, and periodic 24 hour urine collections, imaging (low-dose CT scan or ultrasound) and follow-up questionnaires.
94 studies on the registry are indexed under Urinary Calculi; 20 are open to participants now.
This study's enrollment of 1,658 is above the median of 120 across 61 interventional studies indexed under Urinary Calculi.
Browse Urinary Calculi studies →Duke University is the lead sponsor of 2,063 studies on the registry; 273 are open to participants now.
Of its 204 completed or terminated interventional studies of FDA-regulated products, 167 (82%) have results posted.
Counted across the registry records on this site, refreshed daily.
Inclusion Criteria:
At least 1 symptomatic stone event (passage or procedural intervention) within 3 years prior to enrollment or a symptomatic stone event within 5 years if the patient also has new stone formation detected on imaging during the last 5 years. Symptomatic stone defined as any of the following:
i. Gross hematuria ii. Renal colic or atypical abdominal pain attributed to the stone, as determined by a treating provider iii. A clinical pattern of intermittent symptoms consistent with intermittent obstruction at the ureteropelvic junction, as determined by a treating provider
Low 24-hr urine volume
Exclusion Criteria:
Known infectious (struvite), monogenic or other causes of stone disease for which therapies are likely to significantly alter course of stone disease
Study participants with comorbidities that preclude high fluid intake or prior surgery precluding high fluid intake or leading to GI fluid losses
i. class II or greater, and/or ii. Hospital admission in the past year for heart failure d. Lung disease with a home oxygen requirement e. Chronic kidney disease ( \<30 ml/min/1.7 m2 over a 3-month period) i. For adults (age ≥18), we will use the CKD-Epi equation which requires the measurement of serum creatinine only. ii. For children (age \<18), we will use the bedside Schwartz (CKiD) formula. f. Nephrotic syndrome (>3.5 grams of protein per 24 hours) g. Cirrhosis with ascites
Exclusions due to medication use:
Individuals with stones composed of medications that may crystallize in the urine (guaifenesin, sulfonamides, triamterene, and the protease inhibitors indinavir and nelfinavir) AND who have discontinued or plan to discontinue these medications.
Note: Individuals who are on long-term medications that increase the risk of stone disease, who cannot stop these medications due to other chronic conditions (e.g., ) and who may reduce their risk for stone recurrence through increased fluid intake, will be eligible to participate in the trial. Examples of these medications include:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
The New York Heart Association’s four classes of how much heart failure limits physical activity.
Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
NYHA class (heart failure)
The New York Heart Association’s four classes of how much heart failure limits physical activity.
Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECOG performance status
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Life expectancy
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants in the intervention arm will receive an individualized "fluid prescription", which will be the additional volume of fluid intake needed to maintain a study-specified urine output. This fluid will be consumed from and measured by a smart water bottle. The intervention arm also includes a behavioral program that consists of financial incentives and structured problem solving (SPS) to maintain the recommended fluid intake.
Behavioral: Fluid prescription · Behavioral: Financial incentive · Behavioral: Structured Problem Solving
Participants in the control arm will receive standard care instructions according to American Urological Association (AUA) guidelines to increase overall fluid consumption to achieve study-specified urine output. They will also receive a "smart" water bottle with capability to self-monitor their fluid intake.
The additional amount of fluid that the participant will need to consume each day, using the smart water bottle, in order to meet the study-specified urine output. This fluid is in addition to any other sources of fluid (ex. cups of coffee, bottled sports drink) that the participant consumes each day.
Participants in the Intervention Arm who meet their fluid intake goal on randomly selected days will receive a small payment for that day.
Structure Problem Solving involves interactions with health coaches to help participants develop feasible solutions to overcoming personal barriers to maintaining the prescribed fluid intake.
Number of Participants With a Symptomatic Stone Event
Having a symptomatic stone event was defined as meeting any 1 of 2 criteria - stone passage or a procedural intervention for a stone (whether the stone was causing symptoms or not).
Time frame: Baseline through approximately 24 months
Number of Participants With Asymptomatic Formation of New Stone
Time frame: Up to approximately 24 months
Number of Participants With Growth of Existing Stone by ≥ 2 mm in Any Dimension
Comparison of the size of any stone on first observation versus later observations or at passage. Will be measured primarily through imaging (CT scan and ultrasound).
Time frame: Baseline through approximately 24 months
Number of Participants With Symptomatic Stone Recurrence, Asymptomatic Stone Formation, or Increase of Existing Stone by ≥2 mm in Any Dimension
Time frame: Baseline through approximately 24 months
24-hour Urine Total Volume
Time frame: 6, 12, 18, and 24 months
Comprehensive Assessment of Self-Reported Urinary Symptoms (CASUS)
The CASUS is a tool used to assess lower urinary tract symptoms (LUTS) in individuals, providing a comprehensive evaluation of various urinary issues. It's designed to capture a wide range of symptoms, including storage, voiding, post-micturition, urgency, incontinence, and abnormal bladder sensations. The total score ranges from 0 to 38, where a higher score indicates greater urinary symptoms.
Time frame: Baseline, 6, 12, 18, and 24 months
Costs of Study Interventions and Treatments for USD During the Follow-up Period
To estimate study intervention costs, we will use a tool specifically designed to estimate costs associated with patient-centered interventions (R01NR011873). The costs of medical resource use will be assigned based on payment schedules (e.g., Medicare). To incorporate potential differences in health-related quality of life experienced by participants in the cost-effectiveness analysis, health state utilities will be estimated from existing literature. Full details of the economic analysis will be specified in the Economic Statistical Analysis Plan.
Time frame: Baseline through approximately 24 months
| Milestone | Intervention | Control |
|---|---|---|
| Started | 826 | 832 |
| Completed | 676 | 691 |
| Not completed | 150 | 141 |
| Withdrew: Death | 0 | 2 |
| Withdrew: Lost to follow-up | 92 | 107 |
| Withdrew: Physician decision | 4 | 2 |
| Withdrew: Pregnancy | 7 | 5 |
| Withdrew: Protocol violation | 0 | 2 |
| Withdrew: Withdrawal by subject | 45 | 23 |
| Withdrew: Technical problems | 2 | 0 |
Having a symptomatic stone event was defined as meeting any 1 of 2 criteria - stone passage or a procedural intervention for a stone (whether the stone was causing symptoms or not).
| Participants | Intervention | Control |
|---|---|---|
| Number of Participants With a Symptomatic Stone Event | 154 | 165 |
| Participants | Intervention | Control |
|---|---|---|
| Number of Participants With Asymptomatic Formation of New Stone | 82 | 83 |
Comparison of the size of any stone on first observation versus later observations or at passage. Will be measured primarily through imaging (CT scan and ultrasound).
| Participants | Intervention | Control |
|---|---|---|
| Number of Participants With Growth of Existing Stone by ≥ 2 mm in Any Dimension | 45 | 32 |
| Participants | Intervention | Control |
|---|---|---|
| Number of Participants With Symptomatic Stone Recurrence, Asymptomatic Stone Formation, or Increase of Existing Stone by ≥2 mm in Any Dimension | 232 | 236 |
| L/day | Intervention | Control |
|---|---|---|
| 6 months | 1.81 (1.30 to 2.38) | 1.58 (1.10 to 2.18) |
| 12 months | 1.70 (1.24 to 2.29) | 1.57 (1.14 to 2.20) |
| 18 months | 1.70 (1.25 to 2.26) | 1.55 (1.13 to 2.09) |
| 24 months | 1.55 (1.18 to 2.10) | 1.47 (1.02 to 20.3) |
The CASUS is a tool used to assess lower urinary tract symptoms (LUTS) in individuals, providing a comprehensive evaluation of various urinary issues. It's designed to capture a wide range of symptoms, including storage, voiding, post-micturition, urgency, incontinence, and abnormal bladder sensations. The total score ranges from 0 to 38, where a higher score indicates greater urinary symptoms.
| score on a scale | Intervention | Control |
|---|---|---|
| Baseline | 6.11 ± 3.298 | 5.94 ± 3.311 |
| 6 months | 6.23 ± 3.197 | 6.11 ± 3.280 |
| 12 months | 6.26 ± 3.442 | 6.05 ± 3.517 |
| 18 months | 6.11 ± 3.267 | 6.11 ± 3.459 |
| 24 months | 6.00 ± 3.283 | 6.01 ± 3.373 |
To estimate study intervention costs, we will use a tool specifically designed to estimate costs associated with patient-centered interventions (R01NR011873). The costs of medical resource use will be assigned based on payment schedules (e.g., Medicare). To incorporate potential differences in health-related quality of life experienced by participants in the cost-effectiveness analysis, health state utilities will be estimated from existing literature. Full details of the economic analysis will be specified in the Economic Statistical Analysis Plan.
Results for this outcome have not been posted.
Collected over Up to approximately 24 months. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Intervention | 0/826 (0%) | 0/826 (0%) | 12/826 (1.5%) |
| Control | 2/832 (0.2%) | 0/832 (0%) | 2/832 (0.2%) |
| Event | Intervention | Control |
|---|---|---|
| Hyponatremia requiring hospitalizationMetabolism and nutrition disorders | 0/826 | 0/832 |
| Event | Intervention | Control |
|---|---|---|
| Asymptomatic hyponatremiaMetabolism and nutrition disorders | 12/826 | 2/832 |
| Age, Continuous(years) | Intervention | Control | Total |
|---|---|---|---|
| Median | 45 (30 to 60) | 44 (27 to 58) | 44 (29 to 59) |
| Sex: Female, Male(Participants) | Intervention | Control | Total |
|---|---|---|---|
| Female | 469 | 477 | 946 |
| Male | 357 | 355 | 712 |
| Ethnicity (NIH/OMB)(Participants) | Intervention | Control | Total |
|---|---|---|---|
| Hispanic or Latino | 46 | 56 | 102 |
| Not Hispanic or Latino | 761 | 757 | 1518 |
| Unknown or Not Reported | 19 | 19 | 38 |
| Race (NIH/OMB)(Participants) | Intervention | Control | Total |
|---|---|---|---|
| American Indian or Alaska Native | 0 | 3 | 3 |
| Asian | 22 | 25 | 47 |
| Native Hawaiian or Other Pacific Islander | 2 | 2 | 4 |
| Black or African American | 55 | 58 | 113 |
| White | 732 | 719 | 1451 |
| More than one race | 7 | 14 | 21 |
| Unknown or Not Reported | 8 | 11 | 19 |
| Region of Enrollment(Participants) | Intervention | Control | Total |
|---|---|---|---|
| United States | 826 | 832 | 1658 |
PDFs hosted by the registry, ClinicalTrials.gov.
Plan to share: Yes — Data and samples, for subjects who consent to sharing, will be sent to the NIDDK Data and Biological Samples Repository following database lock.
Supporting information: Study protocol, Informed consent form, Clinical study report, Analytic code
Time frame: 2 years after the last visit of the last participant randomized.
Access criteria: Anyone with access to the NIDDK Data and Biological Samples Repository
This study is completed, as verified in Jun 2026. You cannot join it, but the record below documents what was studied.
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