Comparison of super-mini PCNL (SMP) versus Miniperc for stones larger than 2 cm: a propensity score-matching study

To compare the efficacy and safety of Super-mini percutaneous nephrolithotomy (SMP, F12-F14) and Miniperc (F18) in the treatment of renal stones of 2-4 cm in size. A prospective comparative analysis of outcomes of patients who underwent SMP and Miniperc for treatment of 2-4 cm renal stones was conducted between July 2014 and January 2017. Demographic data, stone criteria, operative technique, complications, blood transfusion, hemoglobin decrease, stone-free rate (SFR) and length of hospital stay were compared between the two groups. Propensity score-matching (PSM) analysis was performed to further compare the outcomes between the two groups. 79 and 257 patients underwent SMP and Miniperc, respectively. After matching, 73 patients in each group were included. The stone burden was comparable for both groups (3.0 +/- 1.1 vs 3.2 +/- 0.7 cm, p = 0.577). Mean operation time was not significant different between two groups (p = 0.115), while the hospital stay of SMP was much shorter than Miniperc (2.6 +/- 1.4 vs 5.2 +/- 1.8, p < 0.0001). Both groups had similar SFRs in postoperative 1 day and at 1 month follow-up (p = 0.326, p = 0.153), while SMP achieved a markedly higher tubeless rate than Miniperc (84.9 vs 47.9%, p < 0.0001). The total complication rate was significantly lower in SMP (16.4 vs 41.1%, p = 0.0001), and the SIRS rate was markedly lower in SMP group (1.4 vs 12.3%, p = 0.009). SMP is equally effective as Miniperc in the treatment of moderate renal calculi, and has the significant advantage in hospital duration and tubeless rate.