Randomised controlled trialindependent cross-checkabstract only checked I-FAST-09 standard review
Drinking more water to prevent kidney stones
Urinary volume, water and recurrences in idiopathic calcium nephrolithiasis: a 5-year randomized prospective study.
Overview
Borghi L et al.. J Urol 1996 · PMID 8583588
Over five years, stones came back in 12% of those drinking a lot vs 27% without advice.
Does the study support the specific claim? No · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
High water intake and calcium stone recurrence
- How was the study done?
Randomised prospective 5-year study
- How many people, animals or samples were studied?
199 patients; First-episode idiopathic calcium stone formers (plus 101 controls)
- What was actually found?
Recurrence halved.
- How large was the observed effect?
12% vs 27%
- What do the results mean in everyday life?
Stone formers should drink more.
- What are the study's limitations?
Not blinded; Single centre
- What does it say about Elawady's specific claim?
- Do the results apply to Germany and Europe?
Italian; directly applicable.
- What can explicitly not be concluded from this study?
Benefits in people without stones.
Scientific in-depth review
1. Full reference
- Authors
- Borghi L et al.
- Journal
- J Urol
- Year
- 1996
- Identifier
- PMID 8583588
- Verification
- verified – PubMed efetch 2026-10-25 (this agent)
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
not stated in abstract
2. Research question
High water intake and calcium stone recurrence
3. Study design and population
- Study design
- Randomised controlled trial – Randomised prospective 5-year study
- Population
First-episode idiopathic calcium stone formers (plus 101 controls)
- Country
Italy
- Period
5 years
- Sample size
199 patients
- Inclusion and exclusion criteria
As described in the abstract; details not available in abstract.
4. Methods and endpoints
- Exposure / intervention
High water intake
- Comparator
No treatment
- Endpoints
Recurrence; urine supersaturation
- Statistical methods
Group comparison
5. Actual results
- Results
Recurrence 12/99 vs 27/100 (P=0.008); time to relapse 38.7 vs 25.1 months.
- Absolute risks
Recurrence 12% vs 27% over 5 years.
- Authors' conclusion
Urine volume is a real stone risk factor; large water intake is initial therapy for prevention.
6. Strengths
- Randomised
- 5-year follow-up
7. Weaknesses
- Not blinded
- Single centre
8. Risk of bias
- Orienting tool
- RoB 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Open trial.
9. Assessment of the statistical interpretation
Large absolute reduction.
10. Relevance to the specific claim
Contradicts C-FAST-10; limits C-FAST-09.
11. Independent contrary findings
12. Transferability to Germany and Europe
Italian; directly applicable.
13. Overall methodological judgement
Water prevents stones.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | moderate |
| Directness | direct |
| Reproducibility | partly replicated |
| Consistency with the overall evidence | consistent |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
None beyond those stated.
15. Linked fact checks
- Drink water only when thirsty; there is no need to force a fixed daily amount. – Studies contradicting or limiting the claim
- Do not drink much water because it distends the abdomen and raises abdominal pressure; even when thirsty during long fasting hours just wet the lips; fasting three days in a row each week without food and drink is not harsh. – Studies contradicting or limiting the claim
- Drinking a lot of water harms the liver; one should drink only when thirsty and not 'flood' the body with water. – Studies contradicting or limiting the claim