Stone burden alone predicts cost for percutaneous nephrostolithotomy

Dallas-Stone burden, a non-modifiable factor, was the only independent predictor associated with cost for percutaneous nephrostolithotomy (PCNL) in a retrospective study, and its effect was largely driven by a need for second-look flexible nephroscopy.

The study, presented at the AUA annual meeting in Chicago, evaluated 212 procedures performed in 200 patients between September 2005 and May 2007. After excluding patients with simultaneous bilateral PCNL or incomplete data, 179 procedures were analyzed.

Patients had a mean age of 52 years, a median BMI of 30, and 55% were females. Almost 70% were recurrent stone formers, 60% had had prior stone surgery, and 17% were receiving preventive medication. More than half of the patients had multiple stones, and about half had staghorn calculi.

In univariate analysis, stone size category, preoperative UTI, and use of allopurinol (Zyloprim) were the only significant predictors of cost. However, only size category maintained a statistically significant association with cost in multivariate analysis. The median direct cost per PCNL procedure was $6,719, but the range was from $5,749 for non-staghorn stones <2 cm to $8,455 for complete staghorns.

Complication and transfusion rates were not related to stone size. However, operative room time, length of stay, need for multiple accesses, residual fragment rate, and second-look rates all increased with increasing stone size category.

Cost center analyses showed increasing costs for anesthesia, operating room services, radiology, room and board, medication, laboratory, and surgical supplies with increasing stone size category.