Analyzing National Incidences and Predictors of Open Conversion during Minimally Invasive Partial Nephrectomy for cT1 Renal Masses

Objectives: To analyze predictors of open conversion during minimally invasive partial nephrectomy (MIPN) for cT1 renal masses. Methods: The National Cancer Database (NCDB) was investigated for kidney cancer patients who underwent partial nephrectomy (PN) between 2010 and 2015. Patients who underwent MIPN were stratified into converted and nonconverted groups. Sociodemographics, facility characteristics, and surgical outcomes were compared between the two groups, and multivariate logistic regression model was fitted to identify independent predictors of open conversion. Results: In total, 54,246 patients underwent PN for kidney cancer during the 6-year period. Of those, 18,994 (35%) were open partial nephrectomies (OPNs) and 35,252 (64%) were MIPN. Overall, 1010 (2.87%) of MIPNs were converted to OPN. There was an increasing utilization of MIPN from 50.35% in 2010 to 74.73% in 2015. Patients who had open conversion had more 30-day readmissions (5.95% vs 3.31%, p < 0.01). On multivariate analysis; high-volume facility (>30 MIPNs/year), year of surgery (2015 vs 2010), and robotic approach predicted a lower likelihood of conversion (odds ratio [OR] 0.52, confidence interval [CI] 0.44-0.62; OR 0.59, CI 0.47-0.73; and OR 0.31, CI 0.27-0.35; respectively, p < 0.001 for all). Conversely, Medicaid (vs private insurance; OR 1.75, CI 1.39-2.19, p < 0.001) and male sex (OR 1.26, CI 1.11-1.44, p < 0.001) were independent predictors of conversion. Conclusions: Open conversion in MIPN occurred in 2.87% of cases. There was an increasing utilization of MIPN associated with decreased conversion rates. Higher volume hospitals and progressing year of surgery were associated with less likelihood of conversion.