Risk factors for urinary tract infection in nephrolithiasis

Objective: to investigate the impact of renal pelvic and ureteral mucosal infection on the severity of hematuria and inflammation in patients with nephrolithiasis (NLT), to establish risk factors (RFs), and to develop an adequate model for predicting urinary tract infection (UTI). Subjects and methods. The clinical, instrumental, and laboratory data were analyzed in 196 patients with NLT. Methods for pair correlation analysis and for construction of multivariate linear regression models using the EZR v package 1.35 (Saitama Medical Center, Jichi Medical University, Saitama, Japan) were applied to predict the risk of UTI in NLT. The adequacy of the regression model was assessed using the adjusted coefficient of determination (adjusted R-squared value (R2adjusted)). Results. In the presence of UTI, the age of patients was established to have a significant impact on the severity of microhematuria in NLT. In patients with comorbidity of NLT and type 2 diabetes mellitus, UTI was found more frequently (p=0.027), the count of red blood cells in urine increased by 66.3% (p=0.014), and gross hematuria was more common (p=0.034). There was evidence that the size and localization of calculi in the renal pelvis and ureter were RFs for UTI in patients with NLT. The occurrence of UTI in the presence of renal pelvic (>50-mm) and ureteral (>10-mm) calculi was accompanied by the increasing severity of microhematuria. The diagnostic model based on the studied factorial signs demonstrated the high effectiveness of UTI prediction in NLT: the area under the receiver operating characteristic (ROC) curve (AUC) was 0.892 (95% confidence interval (CI), 0.768–0.963); the sensitivity was 88.9% (95% CI, 65.3-98.6), and the specificity was 90.0% (95% CI, 73.5–97.9).