Fig. 4
a: Forest plot under the fixed effects model stratified by whether any method for patient characteristics matching was utilized in each study. The subgroup analysis demonstrates a statistically significant reduction in the odds for mild complications in robotic compared to the open approach in both subgroups (for the studies without patient matching: petoOR = 0.49, CI95%: [0.37; 0.65], and for the studies with patient matching: petoOR = 0.55, CI95%: [0.42; 0.73]). b: Meta-regression analysis bubble plot and regression line, along with its 95% confidence interval, for the overall estimate of the effect in log scale, by year, and for the subgroup of studies with patient matching. This graph demonstrates a statistically significant difference between the two approaches that is progressively expanding after 2015, in favor of the robotic approach. c: Corresponding meta-regression analysis bubble plot for the subgroup of studies without patient matching. According to this graph, patients undergoing robotic partial nephrectomy are less prone to the development of mild postoperative complications, while the relative benefit seems to remain almost time constant. Abbreviations: CD: Clavien–Dindo classification of postoperative complications