China: Groundbreaking Study on Renal Pelvis Urine Density

In a groundbreaking multi-center prospective study, researchers have unearthed a crucial association between renal pelvis urine density and the peril of severe infectious complications in patients with symptom-free hydronephrosis following shock wave lithotripsy (SWL). The findings, which have significant implications for post-lithotripsy patient care, were published in the latest edition of the renowned medical journal Urolithiasis.

The study revealed a positive linear association between Hounsfield units (HU) in renal pelvis urine and the risk of severe infectious complications in patients with ureteral stones and symptom-free hydronephrosis after SWL, irrespective of gender, age, BMI, stone location, stone size, and hydronephrosis grade. The findings might be helpful in the SWL treatment decision-making process.

"There was a linear association between higher HU values and increased infection risk, & a cut-off value of 12.0 HU was determined, providing 85.94% specificity and 78.59% sensitivity," the researchers reported.

Shock wave lithotripsy, a commonly employed non-invasive procedure for kidney stone removal, has revolutionized urological practice over the past few decades. However, despite its effectiveness, certain patients develop symptom-free hydronephrosis post-SWL, posing a clinical conundrum regarding optimal management strategies and risk assessment for potential complications. So, finding easy-to-obtain and reliable predictors of severe infectious complications after shock wave lithotripsy is a major clinical need, particularly in symptom-free hydronephrosis.

Zhenhua Li, Shengjing Hospital of China Medical University, Shenyang, Liaoning, People’s Republic of China, and colleagues aimed to prospectively investigate the predictive value of Hounsfield units in renal pelvis urine for the risk of severe infectious complications in patients with ureteral stones and symptom-free hydronephrosis after SWL.

For this purpose, the researchers conducted a multi-center prospective study from June 2020 to December 2023. The HU of renal pelvis urine was measured by non-enhanced computed tomography. The severe infectious complications included septic shock, sepsis, and systemic inflammatory response syndrome. Finally, the researchers enrolled 1,436 patients with ureteral stones.

Key Findings

• 8.9% of patients experienced severe infectious complications after SWL treatment.
• After adjusting confounding variables, compared with the patients in the lowest renal pelvis urine density quartile, the OR for the highest quartile was 32.36.
• There was a positive linear association between the HU value of renal pelvis urine and the risk of severe infectious complications after SWL.
• This association was also seen stratified by age, gender, BMI, stone size, stone location, and hydronephrosis grade.
• The nonlinear association employed by restricted cubic splines is not statistically significant.
• The AUROC and 95%CI of renal pelvis urine density were 0.895.
• The cut-off value was 12.0 HU with 78.59% sensitivity and 85.94% specificity.

"The findings underscored the potential of renal pelvis urine density, measured in HU, as a reliable predictor for infectious complications post-SWL in patients with ureteral stones and symptom-free hydronephrosis," the researchers wrote.

Reference

Liu, D., Liu, J., Li, Z. et al. The association between renal pelvis urine density and the risk of severe infectious complications in patient with symptom-free hydronephrosis after shock wave lithotripsy: a multi-center prospective study. Urolithiasis 52, 72 (2024). https://doi.org/10.1007/s00240-024-01572-5