[Standarization of PCNL reporting: Comparative methodology.]

To evaluate the impact of a new renal lithiasis classification on the stone free rate. The new system would allow standarization of comparison between different series of percutaneous nephrolithotomy.

Patients undergoing NPCL between November 2011 and November 2016 were retrospectively analyzed. The stones were classified as simple (pelvic and/or calyceal stones that required a single access and/or use of a rigid nephroscope), complex (required the use of more than one percutaneous access and/or flexible instruments and/or combined access) and extremely complex (complete staghorn stones or anatomical alterations), according to the Ibarluzea-Llanes classification. Other variables analyzed were age, sex, diabetes, hypertension or taking anticoagulants, stones composition, placement of postoperative nephrostomy and surgical time. We performed a univariate and multivariate analysis using the chi-square or Fisher test and logistic regression.

Sixty-nine procedures were included in 57 patients with a mean age of 51 years (13-84) and a mean follow-up time of 30 months. The stone free rate was 86%, 75% and 55% for a simple, complex or extremely complex stone, both at three months and a year. Only the stone type was associated with a worse stone free rate (p 0.03) with RR of 2.5 for a 95% CI.

The Ibarluzea-Llanes clasification could be used as a new system for standarization of PCNL outcomes reporting.