title: Simple and practical nomograms for predicting the stone-free rate after shock wave lithotripsy in patients with a solitary upper ureteral stone.
abstract: OBJECTIVE
  To develop practical nomograms for predicting the stone-free rate after shock wave lithotripsy (SWL) in patients with a solitary stone in the proximal ureter.
  
  
  METHODS
  Between July 2006 and June 2015, 319 patients with a proximal ureteral stone who underwent preoperative non-contrast enhanced computed tomography (NCCT) and subsequently received SWL were identified. Patients' age, gender, laterality, stone size, mean and maximum Hounsfield Unit (HU) of the stone, and skin-to-stone distance (SSD) were assessed. The stone-free status was defined as no radiopacity detected on the 3-month follow-up plain radiography or NCCT.
  
  
  RESULTS
  Mean stone size was 10 mm (range 3-20 mm). Mean and maximum HU of the stone ranged from 115 to 1447 (mean 701) and from 265 to 1881 (mean 1062), respectively. The overall stone-free rate was 70%. Multivariate analyses identified stone size (p < 0.001), maximum HU (p < 0.001), and SSD at 90° (p = 0.038) as independent predictive factors for the stone-free status after SWL. Nomograms could be constructed for predicting the probability of stone-free status after SWL corresponding to SSD of 8, 10, and 12 cm using maximum HU and stone size.
  
  
  CONCLUSIONS
  This study demonstrated that stone size, maximum HU of the stone, and SSD at 90° are significant predictors of successful SWL outcome in patients with a proximal ureteral stone. We have developed simple and practical nomograms corresponding to three different SSDs for predicting the stone-free rate after SWL.
authors.affiliation: Department of Urology, Keio University School of Medicine, Shinanomachi 35, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Niwa
authors.affiliation: Department of Urology, Keio University School of Medicine, Shinanomachi 35, Shinjuku-ku, Tokyo, 160-8582, Japan. kazz_matsumoto@yahoo.co.jp.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Matsumoto
authors.affiliation: Department of Urology, Irumagawa Hospital, Gion 17-2, Sayama, Saitama, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Miyahara
authors.affiliation: Department of Urology, Keio University School of Medicine, Shinanomachi 35, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Minami
authors.initials: M
authors.lastname: Omura
authors.affiliation: Department of Urology, Keio University School of Medicine, Shinanomachi 35, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kobayashi
authors.affiliation: Department of Urology, Keio University School of Medicine, Shinanomachi 35, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Kikuchi
authors.affiliation: Department of Urology, Keio University School of Medicine, Shinanomachi 35, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Miyajima
authors.affiliation: Department of Urology, Irumagawa Hospital, Gion 17-2, Sayama, Saitama, Japan.
authors.forename: Kazutoyo
authors.initials: K
authors.lastname: Miyata
authors.affiliation: Department of Urology, Keio University School of Medicine, Shinanomachi 35, Shinjuku-ku, Tokyo, 160-8582, Japan.
authors.forename: Mototsugu
authors.initials: M
authors.lastname: Oya
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008096:Lithotripsy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D049451:Nomograms; D011379:Prognosis; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D014514:Ureteral Calculi / Q000000981:diagnostic imaging / Q000628:therapy*; D055815:Young Adult
keywords: Hounsfield unit; Lithotripsy; Nomograms; Shock wave lithotripsy; Skin-to-stone distance; Urinary calculi