Does the presence or degree of hydronephrosis affect the stone disintegration efficacy of extracorporeal shock wave lithotripsy? A systematic review and meta-analysis

The aim of this study was to determine whether the presence or degree of hydronephrosis (HN) affects the stone disintegration efficacy of shock wave lithotripsy (SWL). A comprehensive literature search using PubMed, Embase, Cochrane Library, and Web of Science was conducted to retrieve relevant studies. Risk ratios (RRs) and mean differences (MDs) with corresponding 95% confidence intervals (CIs) were calculated for comparisons of outcomes of interest. In total, seven comparative studies with 2033 patients were included. Overall results indicated no significant difference in stone-free rate (SFR) and retreatment rate between two groups. Subgroup analysis further revealed: (1) compared with moderate or severe HN, non-HN SWL brought significantly lower retreatment rate (RR 0.67, 95%CI 0.52–0.87, P = 0.002 and RR 0.55, 95%CI: 0.40–0.76, P = 0.0003, respectively) and shorter clearance time (MD − 3.80, 95%CI − 5.81 to − 1.79, P = 0.0002 and MD – 5.93, 95%CI − 10.29 to − 1.57, P = 0.008, respectively); (2) SWLs performed without stone-induced HN or with artificial HN were associated with significantly higher SFR (RR 1.11, 95%CI 1.04−1.18, P = 0.001 and RR 0.93, 95%CI 0.87−0.99, P = 0.02, respectively); (3) non-HN SWL brought significantly higher SFR than HN group when treating proximal ureteral stones (RR 1.14, 95%CI 1.04–1.24, P = 0.005). Generally, SWLs performed with HN were shown to offer similar stone disintegration efficacy to those without HN. However, it seemed preferable to perform SWL: (1) without severe to moderate HN or stone-induced HN; (2) with artificial HN; (3) without HN when treating proximal ureteral stones.