High water intake in preventing the risk of Uric Acid Nephrolithiasis: A systematic review and meta-analysis

Background: Hyperuricosuria, persistently low urinary pH, and low urinary volume are the main risk factors of uric acid nephrolithiasis. Epidemiologic studies suggest that high water intake is protective against the occurrence of symptomatic kidney stone events of all types. The objective of this systematic review and meta-analysis were to evaluate the effectiveness of increased water intake to prevent symptomatic uric acid kidney stone events. Methods: Seventeen studies were identified for the meta-analysis. Analysis of Q and I2% statistics revealed that a high heterogeneity in 16 studies, thus, random effects model was used. Protective associations were identified for high water intake individuals (SMD=0.52 L; 95% CI: 0.19, 0.84; p=0.002); a significantly decreased relative super saturation of uric acid versus controls (SMD=-1.15; 95% CI: -2.00, -0.30; p=0.008). Risk factors including urinary uric acid excretion and pH were not significantly related to high water intake (SMD=7.32mg/d, 95% CI: -52.27, 66.91; p=0.81), (SMD=0.14; 95% CI: -0.02, 0.31; p=0.09), respectively. Further subgroup analyses revealed that urinary uric acid excretion was significantly decreased in healthy individuals (SMD=-36.23 mg/d, 95% CI: -65.14, -7.31; p=0.001) compared to stone formers (SMD=27.41 mg/d, 95% CI: -33.18, 88.01; p=0.38); urinary uric acid excretion was significantly decreased in routine water intake groups (SMD=-61.49 mg/d, 95% CI: -120.74, 12.24; p=0.04) compared to mineral water intake groups (SMD=44.50 mg/d, 95% CI: -18.30, 107.29; p=0.16); urinary pH was significantly higher in mineral water groups (SMD=0.13, 95% CI: 0.01, 0.46; p=0.04) compared to regular water groups (SMD=-0.00, 95% CI: -0.13, 0.13; p=0.98). Results: A total of 129 patients had 150 internal jugular catheter insertions. The mean age was 51.4±15.2 years with male to female ratio of 1.5:1. All the patients had chronic kidney disease; about 80% had tunneled IJC and 96.9% of the catheters were inserted in the right internal jugular vein. Immediate complications were recorded in 10% and late complications in 34.9% of the procedures. The immediate complications were kinking of guide wire (2%), arterial puncture (1.3%) and difficulty in locating the internal jugular vein (1.3%) or tunneling (1.3%). The late complications were infection (12.8%), poor blood flow (9.2%), bleeding (5.5%) and spontaneous removal of the catheter (5.5%). There was no statistical significant difference in both immediate and late complication with age and sex. Conclusion: This meta-analysis identified evidence that urinary uric acid excretion, volume, pH and relative supersaturation of uric acid can be altered with high water intake intervention, reducing the risk of uric acid kidney stones