title: Evaluation of preoperative bioimpedance spectroscopy quantification of body composition on predicting postoperative outcomes following robotic assisted radical prostatectomy (RARP).
abstract: BACKGROUND
  Bioimpedance spectroscopy (BIS) is a novel, precise quantification of body composition (BC) using low electrical currents through tissue.  Accurate BC quantification may better predict postoperative outcomes.  We compared BIS-BC and body mass index (BMI) for correlation with post-surgical outcomes in robotic assisted radical prostatectomy (RARP) patients.
  
  
  METHODS
  Preoperative BIS-BC and BMI analyses were conducted on men with biopsy-proven prostate cancer undergoing RARP.  Height, weight, percentage and fat mass (PFM, FM), percentage and fat-free mass (PFFM, FFM), percentage and total body water (PTBW, TBW), and percentage and intracellular/extracellular water (PICW, PECW, ICW, ECW) were obtained using the ImpediMed SFB7 Device (San Diego, CA, USA).  Preoperative PSA, biopsy and pathologic Gleason scores, prostate volume, percentage tumor volume, margin status, operative time, estimated blood loss (EBL) and pathologic stage were recorded.  Spearman's rank correlation was estimated to evaluate the association between BIS-BC results, BMI, and post-surgical outcomes.
  
  
  RESULTS
  Between April 2009 and August 2010, 63 men had been enrolled in this ongoing study.  Fourteen were of normal weight (18.5 kg/m2-24.9 kg/m2), 33 were overweight (25 kg/m2-29.9 kg/m2) and 16 were obese (BMI ≥ 30 kg/m2).  Mean age was 60.7 years, mean preoperative PSA was 7.4 ng/mL, and median Gleason was 7.  BMI correlated with FFM (p = 0.002), FM (p = 0.01), and PTBW (p = 0.02).  FM correlated with preoperative PSA (p = 0.01).  PFFM (p = 0.03), PFM (p = 0.03) and PTBW (p = 0.04) correlated with % tumor volume.  ICW (p = 0.01) and TBW (p = 0.009) correlated with EBL.  BMI (p = 0.04), PECW (p = 0.04), FM (p = 0.05), and PICW (p = 0.03) correlated with pathologic tumor stage.
  
  
  CONCLUSIONS
  BMI correlates with BIS-BC FFM, FM and PTBW.  PFFM, PFM and PTBW correlated with % tumor volume.  ICW and TBW correlated with EBL.  BMI, PECW, FM, and PICW correlated with pathologic tumor stage.  BIS-BC metrics may be helpful in predicting post-RARP outcomes.  Further study is required to validate these predictions.
authors.affiliation: Department of Urology, Columbia University Medical Center, New York, New York 10032, USA.
authors.forename: Gina M
authors.initials: GM
authors.lastname: Badalato
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Wosnitzer
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Truesdale
authors.forename: Marco
authors.initials: M
authors.lastname: Sandri
authors.forename: Woo Jin
authors.initials: WJ
authors.lastname: Ko
authors.forename: Jaime
authors.initials: J
authors.lastname: Landman
authors.forename: Ketan K
authors.initials: KK
authors.lastname: Badani
mesh_terms: D001706:Biopsy; D001823:Body Composition; D058266:Dielectric Spectroscopy / Q000295:instrumentation*; D017097:Electric Impedance; D004867:Equipment Design; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D057234:Preoperative Period; D011468:Prostatectomy / Q000379:methods*; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000601:surgery; D012189:Retrospective Studies; D012371:Robotics; D016896:Treatment Outcome