INTRODUCTION AND OBJECTIVES: The S.T.O.N.E. nephrolithometry
was previously developed to quantitate stone
complexity. We assessed the ability of nephrolithometry score to
predict stone-free status in a multicenter database of patients
undergoing PCNL.
METHODS: We performed a multicenter retrospective study of
patients undergoing PCNL. Preoperative CT images were reviewed
and S.T.O.N.E. score was assigned to each patient. The
association of S.T.O.N.E. score with patient demographics, stone
characteristics, and surgical outcomes was analyzed.
RESULTS: In total, 706 met inclusion criteria and were included
in the analysis. Mean overall nephrolithometry score was 8.2
(SD = 2.2). Overall single procedure stone-free rate was 69%. In
logistic regression analysis, S.T.O.N.E. score was significantly
associated with postoperative stone-free status (P < 0.001). Stonefree
patients had statistically significant lower S.T.O.N.E. scores
than patients with residual stones (7.7 vs. 9.1, respectively;
P < 0.001). On average, for each increase in one unit of S.T.O.N.E
score, odds of being stone-free decreased by 32%. In risk stratification,
low-risk patients with 5–7 scores had 22.8% of residual
stones, compared to medium-risk (8–10) and high-risk patients
(11–13) who had 50.8% and 66.7% of residual stones, respectively
(p = 0.001). On average, compared to scores 5–7, scores 8–
10 and 11–13 have a decrease in the odds of being stone free by
71% and 85%, respectively.
CONCLUSIONS: In a multicenter study including data
from multiple surgeons, S.T.O.N.E. nephrolithometry accurately
predicted stone-free rate following PCNL. The easy-to-use
scoring system obtained from CT imaging may be utilized in
preoperative patient counseling, surgical planning, quality assessment,
and as a standardized measure to evaluate outcomes
across different series.
SOURCE OF FUNDING: None