Perks Alexandra E, Schuler Trevor D, Lee Jason, Ghiculete Daniela, Chung Dae-Gyun, D'A Honey R John, Pace Kenneth T
Division of Urology, Department of Surgery, and the Department of Radiology, St. Michael's Hospital and University of Toronto, Toronto, Ontario, Canada.
Urology. 2008 Oct;72(4):765-9. doi: 10.1016/j.urology.2008.05.046. Epub 2008 Jul 31.
To determine whether stone attenuation and the skin-to-stone distance (SSD) can predict for stone fragmentation by SWL independently. Identifying the factors predictive of shock wave lithotripsy (SWL) outcome would help streamline the care of patients with stones.
A retrospective review was performed of 111 patients undergoing initial SWL for a solitary, 5-20 mm, renal calculus. Stone size, location, attenuation value, and SSD were determined on pretreatment noncontrast computed tomography. The outcome was categorized as stone free, complete fragmentation <5 mm, and incomplete fragmentation >or=5 mm or unchanged at 2 weeks on kidney/ureter/bladder radiography.
After SWL, 44 (40%) were stone free, 27 (24%) had complete fragmentation, and 40 (36%) of 111 patients had incomplete fragmentation. The stone attenuation of the successfully treated patients (stone free and complete fragmentation groups) was 837 +/- 277 Hounsfield units (HU) vs 1092 +/- 254 HU for those with treatment failure (incomplete fragmentation; P < .01). The mean SSD also differed: 9.6 cm +/- 2.0 vs 11.1 cm +/- 2.5 for the successful treatment group vs the treatment failure group, respectively (P = .01). On multivariate analysis, the factors that independently predicted the outcome were stone attenuation, SSD, and stone composition. When patients were stratified into 4 risk groups (stone <900 HU and SSD <9.0 cm, stone <900 HU and SSD >or=9.0 cm, stone >or=900 HU and SSD <9.0 cm, and stone >or=900 HU and SSD >or=9.0 cm), the SWL success rate was 91%, 79%, 58%, and 41%, respectively (odds ratio 7.1, 95% confidence interval 1.6-32 for <900 HU and SSD <9.0 cm group vs other 3 risk groups; P = .01).
The results of our study have shown that a stone attenuation of <900 HU, SSD of <9 cm, and stone composition predict for SWL success, independent of stone size, location, and body mass index. These factors will be considered important in the prospective design of a SWL treatment nomogram at our center.
确定结石衰减值和皮肤至结石距离（SSD）能否独立预测体外冲击波碎石术（SWL）后结石的粉碎情况。识别预测冲击波碎石术（SWL）治疗结果的因素将有助于优化结石患者的治疗。
对111例因单发、直径5 - 20 mm肾结石接受初次SWL治疗的患者进行回顾性研究。在治疗前的非增强计算机断层扫描上确定结石大小、位置、衰减值和SSD。结局分为结石清除、完全粉碎至<5 mm、不完全粉碎至≥5 mm或2周时在肾脏/输尿管/膀胱平片上结石无变化。
SWL治疗后，44例（40%）结石清除，27例（24%）完全粉碎，111例患者中有40例（36%）不完全粉碎。成功治疗的患者（结石清除和完全粉碎组）的结石衰减值为837±277亨氏单位（HU），而治疗失败（不完全粉碎）的患者为1092±254 HU（P <.01）。平均SSD也不同：成功治疗组为9.6 cm±2.0，治疗失败组为11.1 cm±2.5（P =.01）。多因素分析显示，独立预测治疗结果的因素为结石衰减值、SSD和结石成分。当患者被分为4个风险组（结石<900 HU且SSD<9.0 cm、结石<900 HU且SSD≥9.0 cm、结石≥900 HU且SSD<9.0 cm、结石≥900 HU且SSD≥9.0 cm）时，SWL成功率分别为91%、79%、58%和41%（<900 HU且SSD<9.0 cm组与其他3个风险组相比，优势比为7.1，95%置信区间为1.6 - 32；P =.01）。
我们的研究结果表明，结石衰减值<900 HU、SSD<9 cm和结石成分可预测SWL治疗成功，与结石大小、位置和体重指数无关。在我们中心，这些因素在SWL治疗列线图的前瞻性设计中将被视为重要因素。
