RENAL nephrometry score is associated with complications after renal cryoablation: a multicenter analysis

Objective: To analyze outcomes and complications of percutaneous (PRC) and laparoscopic renal cryoablation (LRC) using the radius, endophytic, nearness to collecting system, anterior/posterior, and location (RENAL) nephrometry system.

Methods: Retrospective multicenter analysis of 154 consecutive patients who underwent either ultrasound-guided LRC (n = 88) or computed tomography (CT)-guided PRC (n = 66) from March 2003 to December 2011. RENAL score and demographics were compared to postoperative complications (Clavien). Multivariable analysis was carried out for factors associated with development of postprocedure complications.

Results: Mean age was 68 years (94 men/60 women). Median follow-up was 34 months (range 23.6-45.6 months). Mean tumor size was 2.6 ± 1 cm. Mean RENAL score was 5.2 ± 1.4. Differences in (A)nterior/posterior component and (H)ilar domain of the RENAL scores were noted, with PRC favoring posterior tumors and hilar lesions compared to LRC (P < .001 and P = .044, respectively). There were 14.9% complications, all of which were low-grade (Clavien 1,2). There were no differences in complications between LRC and PRC (15.9% vs 13.6%, P = .82). Most common complication type was hemorrhagic in 9 of 154 patients (5.8%); significant increase in the hemorrhagic complication rate was noted for patients with "N" ("nearness") component score of 2 or 3 (5/36, or 13.9%), compared to patients with "N" score of 1 (4/115 or 3.5%, P = .033). multivariable analysis demonstrated that increasing RENAL score was associated with postprocedure complications (odds ratio [OR] = 1.37, P = .025). When separated into individual domains, multivariable analysis revealed that "N" score 3 was significantly associated with postoperative complications (OR 16.15, P = .027).

Conclusion: Increasing RENAL score was associated development of postprocedure complications after renal cryotherapy. Further investigation is requisite to elucidate the role of RENAL nephrometry score in risk stratification prior to renal cryotherapy.