RESUMO
Objective To evaluate stone retention time coefficient (RTC) times stone size value (RTC × S) as the indication of extracorporeal shockwave lithotripsy (ESWL) efficacy in the treatment of upper ureteral calculi.Methods From January 2009 to May 2011,180 consecutive patients including 109males and 71 females who underwent ESWL for a single radiopaque upper ureteral stone with the mean stone size (0.9 ± 0.2) cm and the mean stone retention time (12.6 ± 9.7) d were retrospectively analyzed.The mean patient age was 39 years (range from 21 to 65 years).The base of RTC was set as 1 and each 0.1 was added on it if the stone stayed one more week in upper ureter.Patients were classified into 2 groups by stone size.105 patients were in group ＜ 1 cm and 75 patients were in group≥ 1 cm.According to RTC × S value,79 patients were in group ＜ 1 and 101 patients were in group≥ 1.Stone-free rate between these two groups in the same grouping indication and between two matched groups in the different grouping indication were compared respectively.The chi-square test compared categorical variables between the two groups and all statistical analyses were 2-sided with P ＜ 0.05 defined as statistically significant.Results The overall stone-free rate of group ＜ 1 cm was significantly higher than that of group≥ 1 cm (81.9％ vs.68.0％,P ＜0.05).The overall stone-free rate of group RTC × S value ＜ 1 was significantly higher than that of group RTC × S value ≥1 (96.2 ％ vs.60.4％,P ＜ 0.05).Comparison between two matched groups showed that the stone-free rate of group RTC S value ＜ 1 was significantly higher than that of group ＜ 1 cm (96.2％ vs.81.9 ％,P＜0.05),but group RTC×Svalue≥1 was comparable to group≥l cm (60.4％ vs.68.0％,P ＞ 0.05).26 patients with ＜ 1 cm stones were enrolled in group ≥ 1 for long stone retention time and larger RTC × S value.The overall stone-free rate of them was 38.5％ (10/26) which was significantly lower than that of group≥ 1 cm (P ＜ 0.05).Conclusions The stone retention time is an important factor in efficacy of ESWL for upper ureteral calculi.Use RTC × S as a new indication of ESWL,not only the stone size but stone retention time is taken into account as well.ESWL is highly efficacious in patients with RTC × S values ＜ 1.