National rates and risk factors for stent failure after successful insertion in patients with obstructed, infected upper tract stones

Introduction: We report the incidence of stent failure, defined as the need for salvage percutaneous nephrostomy (PCN) placement following the placement of a ureteral stent, in patients with infection of an obstructed urinary tract secondary to urolithiasis. We also sought to identify risk factors associated with ureteral stent failure. Methods: Using the Nationwide Inpatient Sample, we used time trend analysis to examine the incidence of ureteral stent failure for infected urolithiasis, as well as the estimated annual percent change (EAPC) from 1998 to 2010. Logistic regression was performed to estimate the odds of stent failure based on patient and hospital characteristics. Results: A total of 164 546 stents were placed during the study period. Of these, 97.8% resulted in successful decompression. The rates of successful stent decompression and stent failure increased over time (EAPC 14.05%, p < 0.001; EAPC 11.61%, p < 0.001). Middle-aged males with renal stones and acute kidney failure had higher odds of stent failure (p < 0.05). Salvage percutaneous nephrostomies were performed most frequently in urban teaching institutions (odds ratio [OR] 1.98, p = 0.001; OR 1.83, p < 0.001). Conclusions: Ureteral stent decompression for an infected obstructed urinary tract secondary to urolithiasis is almost always effective. For a small proportion of patients, stent failure will occur and will require the placement of a nephrostomy tube. Stent failure is associated with male gender, stone location, and renal failure. Salvage percutaneous nephrostomies for these patients occur most frequently in urban teaching hospitals. Of note, this study was limited by the presumption that coding for a PCN after stent placement indicated stent failure, which could not be verified because of the inherent limitations of the dataset.