Risk Factors for Readmission after Shock Wave Lithotripsy for Urinary Stones.

Introduction: Cost saving measures have put an increased emphasis on reducing complications and rehospitalization. We analyzed the rate of readmission and presentation to emergency departments within 90 days of shock wave lithotripsy to identify prognostic risk factors for this outcome.

Methods: We retrospectively reviewed patients who underwent shock wave lithotripsy at our institution from January 2011 to May 2013 using the Modulith® SLX-F2 lithotripter for solitary ureteral or renal stones 2.0 cm or smaller. The primary outcome was readmission or presentation to the emergency department within 90 days. Secondary end points included stone-free rates at 30 and 90 days. Univariate and multivariate logistic regression analyses were performed to identify risk factors for primary and secondary outcomes.

Results: The study population consisted of 307 patients with renal and 270 with ureteral stones. Mean stone size was 9.2 mm. The 90-day readmission rate was 11.6%. Of analyzed metrics only urgency of procedure predicted readmission. Among patients who were readmitted renal colic was the most common chief complaint (67%), followed by infection (10%) and postoperative hematoma or hematuria (7.5%). Stone-free rates were 57% and 78% at 30 and 90 days, respectively. Stone size and nonurgent shock wave lithotripsy status predicted stone-free status.

Conclusions: The 90-day readmission rate following shock wave lithotripsy was 11.6%. Urgency of shock wave lithotripsy was predictive of this outcome. Stone centers should monitor their readmission rates following shock wave lithotripsy to establish national standards and guide decision making when considering other endourological methods if these outcomes are considered unacceptable.