Comparison of mini percutaneous nephrolithotomy and standard percutaneous nephrolithotomy for renal stones > 2cm: a systematic review and meta-analysis

Background: The purpose is to compare the efficacy and safety of mini percutaneous nephrolithotomy (mini-PCNL) versus standard percutaneous nephrolithotomy (standardPCNL) in patients with renal stones >2cm. Materials and Methods: A systematic literature search was conducted in PubMed, Web of Science, Scopus, and the Cochrane Library databases to identify relevant studies before March 8, 2021. Stone-free rate (SFR), operation time, fever rate, hemoglobin drop, blood transfusion rate, and hospitalization time were used as outcomes to compare mini-PCNL and standard-PCNL. The meta-analysis was performed using the Review Manager version 5.4. Results: Seven randomized controlled trials were included in our meta-analysis, involving 1407 mini-PCNL cases and 1436 standard-PCNL cases. Our results reveal that, for renal stones >2cm, mini-PCNL has a similar SFR (risk ratio (RR)=1.01, 95% confidence interval (CI): 0.98 to 1.04, p=0.57) and fever rate (RR=1.22, 95% CI: 0.971.51, p=0.08). Standard-PCNL was associated with a significantly shorter operating time (weighted mean difference (WMD)=8.23, 95% CI: 3.44 to 13.01, p <0.01) and a longer hospitalization time (WMD=-20.05, 95% CI: -29.28 to -10.81, p <0.01) than mini-PCNL. Subgroup analysis showed hemoglobin drop and blood transfusion for 30F standardPCNL were more common than mini-PCNL (WMD=-0.95, 95% CI: -1.40 to -0.50, p <0.01; RR=0.20, 95% CI: 0.07 to 0.58, p <0.01). Conclusion: In the treatment of >2cm renal stones, mini-PCNL should be considered an effective and reliable alternative to standard-PCNL (30F). It achieves a comparable SFR to standard-PCNL, but with less blood loss, lower transfusion rate, and shorter hospitalization. However, the mini-PCNL does not show a significant advantage over the 24F standard-PCNL. On the contrary, this procedure takes a longer operation time.