Conversion of Robot-assisted Partial Nephrectomy to Radical Nephrectomy: A Prospective Multi-institutional Study

To assess the incidence and factors affecting conversion from robot-assisted partial nephrectomy (RAPN) to radical nephrectomy.

Between November 2014 and February 2017, 501 patients underwent attempted RAPN by 22 surgeons at 14 centers in 9 countries within the Vattikuti Collaborative Quality Initiative database. Patients were permanently logged for RAPN prior to surgery and were analyzed on an intention-to-treat basis. Multivariable logistic regression with backward stepwise selection of variables was done to assess the factors associated with conversion to radical nephrectomy.

Overall conversion rate was 25 of 501 (5%). Patients converted to radical nephrectomy were older (median age [interquartile range] 66.0 [61.0-74.0] vs 59.0 [50.0-68.0], P = .012), had higher body mass index (BMI) (median 32.8 [24.9-40.9] vs 27.8 [24.6-31.5] kg/m², P = .031), higher age-adjusted Charlson comorbidity score (median 6.0 [4.0-7.0] vs 4.0 [3.0-5.0], P <.001), higher American Society of Anesthesiologists score (score ≥3; 13/25 (52.0%) vs 130/476 (27.3%), P = .021), Preoperative estimated glomerular filtration rate (P = .141), clinical tumor stage (P = .145), tumor location (P = .140), multifocality (P = .483), and RENAL (radius, exophytic/endophytic properties, nearness of tumor to the collecting system or sinus in millimeters, and anterior/posterior location relative to polar lines) nephrometry score (P = .125) were not significantly different between the groups. On multivariable analysis, independent predictors for conversion were BMI (odds ratio [95% confidence interval]; 1.070 [1.018-1.124]; P = .007) and Charlson score (odds ratio [95% confidence interval]; 1.459 [1.179-1.806]; P = .001).

RAPN was associated with a low rate of conversion. Independent predictors of conversion were BMI and Charlson score. Tumor factors such as clinical stage, location, multifocality, or RENAL score were not associated with increased risk of conversion.