Comparison Between Guys Stone Score and S.T.O.N.E Score in Patients Undergoing Percutaneous Nephrolithotomy

Background: This study was conducted to estimate the stone-free rates and complication rates in patients with different grades of Guy’s stone score and S.T.O.N.E. nephrolithometry scores undergoing percutaneous nephrolithotomy, study the correlation between Guy’s stone score and S.T.O.N.E. score and operative times, length of hospital stay and other selected outcomes, and compare the area under the curve for Guy’s stone score and S.T.O.N.E. score for post-percutaneous nephrolithotomy outcomes. Methods: This was a hospital-based prospective observational study conducted among 164 patients who underwent Percutaneous Nephrolithotomy (PCNL) in the Department of Urology, Government Medical College, Thiruvananthapuram, over a period of one year, after obtaining clearance from the institutional ethics committee and written informed consent from the study participants. Results: The mean Guys stone score in the study population was 1.75 ± 0.95, whereas the mean S.T.O.N.E score was 7.45 ± 1.22. The overall complication rate in our study was 25.61%. The complication rates had a significant correlation with the Guys stone score (p<0.0001) as well as with the S.T.O.N.E. score (p<0.0001). There was a significant correlation between the Guys stone score and stone free rate (p < 0.0001) as well as between the S.T.O.N.E. score and stone free rate (p < 0.0001). Conclusion: Both GSS and STONE scores are equally effective in predicting the success rate as well as complication rates associated with PCNL. Operative time and length of hospital stay also correlate with both scores studied. However, the fluoroscopy time does not correlate with either scoring systems used.