CUA 2018: Effects of a Changing Patient Population on Percutaneous Nephrolithotomy Outcomes

Halifax, Nova Scotia ( Percutaneous nephrolithotomy (PCNL) remains the treatment of choice for large kidney stones. According to current guidelines of both leading Urological organizations such American Urological Association as well as the European Association of Urology, PCNL is the gold standard for stones larger than 2cm. Due to complex nature of the procedure, there have been many modifications proposed to improve the outcomes of the procedure. These changes are thought to improve the surgical outcomes. In this regard, studies assessing the PCNL outcomes over time with different types of surgical techniques is of value for the current state of the literature.

This study presented by Dr. Bjazevic, aimed to assess the impact of changes in patient demographics and surgical techniques over a 25-year time period on PCNL outcomes. Study was performed in a retrospective fashion analyzing prospectively maintained database. This analysis included a total of 2554 patients who underwent PCNL procedure between July 1990 and July 2015. Authors reviewed patient demographics, patient comorbidities, stone characteristics as well as procedural characteristics. Adverse events were consistently categorized according to the Clavien-Dindo classification. Stone free status was defined as no residual fragments present on imaging at 3 months follow up after the procedure.

Authors designed a very interesting study. Patients were stratified into chronological equal terciles of 852 consecutive procedures: First from July 1990 to February 200, second tercile included patients who were operated between March 2000 to March 2007 and finally, the third tercile included patients who underwent PCNL between April 2007 to July 2017.

Changes in patient characteristics and surgical techniques over time were evaluated with a Chi square test. Additionally, authors performed a multivariate logistic regression to elucidate changes in operative duration, length of stay, adverse events and stone-free rate. All patients underwent non-contrast computer tomography (CT) within the 3 months after the procedure to detect any residual fragments.

Dr. Bjazevic reported that the comparison of patient characteristics between the terciles revealed an increase in patient age (<p=0.001), body="" mass="" index="" (bmi),="" (p="0.032)," patient="" comorbidities="" (p<0.001),="" and="" asa="" score="" (figure="" 1).<br="">

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Changes in surgical technique over time included increased use of balloon dilator, ultrasonic lithotripter, ureteric stents (figure 2).

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Overtime, there was a decrease in operative time and hospital stay (figure 3). Complication rate was 15% including major (2.5%), transfusion rate 1% and did not change over time. Complication rate increased over time, which significantly correlated with incrased number of comorbidities. (figure 3)

CUA image 3c

Dr. Bjazevic concluded that patient demographics are changing over time. This is most likely due to increased life expectancy of patients leading to older populations with higher rates of comorbidities. PCNL remains a safe and effective procedure for the management of large and complex kidney stones.

Presented by: Jennifer Bjazevic, MD

Written by: Zhamshid Okhunov, MD, Department of Urology, University of California-Irvine, Twitter: @OkhunovZham, at the 73rd Canadian Urological Association Annual Meeting - June 23 - 26, 2018 - Halifax, Nova Scotia