[Risk assessment for complications and stone free status in percutaneous nephrolithotomy]

Percutaneous nephrolithotomy (PNL) is the first line treatment for kidney stones with a diameter > 2 cm. The available scores for measuring success in this procedure only consider the free stone status, without considering the complications.

To present a new prognostic stratification system to predict treatment failure in PNL.

Historic cohort in which prognostic factors and failure as residual stone with or without complication were identified. A bivariate analysis was performed using the numeric variables and with the use of conjunctive consolidation a prognostic stratification system was developed.

A total of 595 cases were included, out of which 73% concluded with free stone status and 12% developed major complications. 66% fulfilled the proposed success definition. In the first conjunct consolidation, a positive urine culture and a complex stone were identified as risk factors; after making one more conjunction with another stratum, the severe Charlson Comorbidity Index (CCI) was also identified as a risk factor. Finally, an operating time ≥ 120 minutes was added as an intraoperative factor that increases risk.

The variables positive urine culture, severe CCI, complex stone and prolonged operating time are associated with major complications and residual stone. The proposed score is a simple and predictive tool that can be used in daily practice, given that it includes 3 pre-operative variables. The treatment success or failure rate of the score can be applied in the selection of patients ongoing PNL.