Oblique supine position versus prone position for percutaneous nephrolithotomy: a systematic review and meta-analysis

Introduction
To compare the efficacy and safety of percutaneous nephrolithotomy (PCNL) in the oblique supine position (OSP) and the prone position (PP).

Aim
To perform a systematic review and meta-analysis to evaluate the efficacy and safety of OSP versus PP for PCNL.

Material and methods
A systematic literature search of PubMed, Ovid, SCOPUS, and citation lists was conducted to identify eligible comparative studies up to November 2022. All studies comparing OSP versus PP for PCNL were included. Statistical analysis was performed with the Collaboration’s Review Manager (RevMan) 5.4 software.

Results
Overall, eight studies were included involving 1185 patients (OSP = 634; PP = 551). There were no statistically significant differences between OSP and PP in age (WMD = –0.95 years; 95% CI: –2.12 to 0.21; p = 0.83) or proportion of male patients (OR = 0.02; 95% CI: –0.03 to 0.08; p = 0.43). We found that OSP was performed more frequently for smaller stone size and patients with higher BMI (WMD = –0.1 cm, 95% CI: –0.18 to –0.02; p = 0.01) and patients with higher BMI (WMD = 0.66 kg/m2; 95% CI: 0.29 to 1.03; p = 0.0005). The operation time was shorter in OSP than PP (WMD = –14 min; 95% CI: –27.00 to –1.00; p = 0.03). The reduction of hemoglobin was lower in OSP than PP (WMD = –0.39 g/dl; 95% CI: –0.60 to –0.13; p = 0.03). There was no significant difference in stone-free rate and hospitalization between the two groups (OR = 1.32; 95% CI: 0.98 to 1.78; p = 0.07; WMD = –5.99 h; 95% CI: –17.15 to 5.16; p = 0.29). The overall complications were fewer in OSP than in PP (OR = 0.59; 95% CI: 0.43 to 0.81; p = 0.001), but no difference was observed between the positions with regard to the major complications (Clavien-Dindo score ≥ 3) (OR = 0.76; 95% CI: 0.43 to 1.34; p = 0.35).

Conclusions
OSP showed non-inferior stone-free rate, blood loss, and hospitalization compared with PP. OSP may be superior in terms of operative time and complications than PP.