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INTRODUCTION: We aimed to investigate the association between stone composition and recurrence rate in a well-characterized group of patients. METHODS: From our prospectively assembled database of 1328 patients undergoing ureteroscopy and percutaneous nephrolithotomy (PCNL) between 2010 and 2015, we identified 457 patients who met the inclusion criteria: a minimum of two years' followup, stone-free status following surgery, normal anatomy, and Fourier transform infrared (FT-IR) stone analysis results. Stone recurrence was identified by kidney-ureter-bladder (KUB) or an ultrasound (US). All symptomatic events were recorded. Kaplan-Meier and Cox proportional hazard regression methods were used to assess the differences in recurrence rates and associated risk factors. RESULTS: Calcium oxalate (CaOx), uric acid (UA), and struvite stones were found in 298 (65.2%), 99 (21.7%), and 28 (6.1%) patients, respectively. During a median followup of 38 months (interquartile range [IQR] 31-48), stone recurred in 111 (24%) patients. One-year stone-free rates (SFRs) stratified by composition were: CaOx 98%, UA 91.9%, calcium phosphate 90%, struvite 88%, and, cystine 83%; the two-year SFRs were 92.6%, 82.7%, 80%, 73%, and 75%, respectively. On multivariate Cox regression analysis, UA composition, the absence of medical preventive therapy, and preoperative stone burden were associated with a shorter time to recurrence. Secondary intervention for recurrent, symptomatic stones was required in 11 (11.1%) and 22 (7.4%) of patients with UA and CaOx stones, respectively (p=0.02). CONCLUSIONS: UA stone-formers are more likely to have a recurrence and to undergo surgical intervention in comparison to CaOx stone-formers, regardless of medical preventive treatment. These differences are more prominent during the first year of followup and should be incorporated into the patient's followup protocol.
RESUMO
INTRODUCTION: Supine percutaneous nephrolithotomy (PCNL) has become increasingly widespread during the last 2 decades. The aim of this study was to analyze the transition from prone to mainly supine PCNL in 2 endourologic centers. MATERIAL AND METHODS: We retrospectively analyzed data on 214 consecutive supine PCNLs divided into the first (2011-2013) and last (2014-2016) 3 years of this study. The first 27 cases were also included in a randomized controlled trial (RCT) by comparison with 24 prone PCNLs. We compared the clinical outcome and implementation rate. The surgical team was surveyed for their overall impression of performing supine PCNLs. RESULTS: The RCT revealed a trend toward shorter operative time (138 vs. 150 minutes), anesthesia time (174 vs. 192 minutes) and hospitalization (2.2 vs. 2.6 days) in the supine PCNL group, without statistical significance and similar stone free rates (SFR) as for the prone PCNL group. Implementation of the supine PCNL reached 96% in 3 years. There was a decrease in operative time (110 vs. 154 minutes; P <0.0001), hospital stay (1.5 vs. 2.1 days; P <0.01), blood transfusion (5% vs. 14%; P <0.05) and rate of ancillary procedures (5% vs. 16%; P <0.05) in the last 3 years of the study. SFR remained stable. Both the surgeons and anesthesiologists expressed their unanimous preference for the supine position over the prone position. CONCLUSIONS: Supine PCNLs are easy to implement without a significant learning curve for an experienced endourologist. They can be employed in complex cases and improve surgeon's ergonomics and anesthesiologist's access to the patient.
