Prognostic Factors for Residual Lithiasis in Patients With Staghorn Calculi Undergoing Percutaneous Nephrolithotomy in the Maya Region of Yucatan, Mexico: A Case-Control Study.

Abstract

Yucatan stands out as the state with the highest prevalence of urolithiasis in Mexico,placing significant demands on healthcare services, such as consultation and surgical intervention. Staghorn calculi are related to recurrent urinary tract infections, and their management is always surgical. The stone-free rate is a parameter used to measure the success of surgery, with residual stones considered those persisting four weeks after surgical management. There are understudied prognostic factors that can predict the success of achieving stone-free status, taking into account the number of stones, their location, and the anatomical variations of the patient's collecting system. The study aims to determine the prognostic factors for residual lithiasis in patients with staghorn calculi treated with percutaneous nephrolithotomy at the High Specialty Regional Hospital of the Yucatan Peninsula. A case-control study was performed including 188 patients, aged 18 years or older, and diagnosed with staghorn calculus from January 2022 to June 2023, grouping the patients according to their stone-free rate evidence on postoperative computed tomography. Data were collected from the records of the Urology Department at a high-specialty hospital in Yucatan. The groups were analyzed, aiming to establish an association between preoperative factors and postoperative outcomes measured in terms of stone-free rate. A total of 188 patients with staghorn calculi were included, with a predominance in females (58.5%) and a mean age of 45.4 ± 11.9 years. The most common comorbidity was hypertension (29.8%), and 27.7% had a history of recurrent urinary tract infections. Regarding the Sampaio classification, B1 was the most prevalent in our population with 66 cases (35.1%), while Type A2 was the least common (13.8%). According to what was obtained through the multivariate logistic regression model, the calyceal anatomy Type A1 and A2 were associated with residual lithiasis (p= 0.016 OR: 2.994 CI: 1.223-7.331), and Grade IV was associated with a higher rate of residual lithiasis (p=0.005 CI: 1.586-13.100).A statistically significant association was found between stone burden and the presence of residual lithiasis (p=< 0.001). Guy's Score Grade IV showed a higher incidence of residual lithiasis,seemingly associated with stone burden, leading to the conclusion that both factors were categorized as predictors for the development of post-surgical residual lithiasis. Regarding anatomical variations according to Sampaio, it was observed that types A1 and A2 showed a lower rate of stone-free status. Therefore, we also consider them as variables that may influence the achievement of success in endourological management. Personalized patient assessment allows for more accurate prognostic factors, enabling a more comprehensive surgical planning in the presence of staghorn calculi.