title: A nomogram to classify men with lower urinary tract symptoms using urine flow and noninvasive measurement of bladder pressure.
abstract: OBJECTIVE
  Bladder pressure during voiding can be estimated by a noninvasive technique using controlled inflation of a penile cuff. This test provides a valid and reliable estimate of isovolumetric bladder pressure but to our knowledge the role of the test for the routine clinical treatment of patients with lower urinary tract symptoms (LUTS) has yet to be demonstrated. As a first step, we evaluated a proposed nomogram for the diagnosis of bladder outlet obstruction in men with LUTS using noninvasive measurements of pressure and flow.
  
  
  METHODS
  Using a combination of theoretical calculation and experimental data the existing International Continence Society pressure flow nomogram was modified to allow noninvasive measurement of isovolumetric bladder pressure in place of detrusor pressure at maximum urine flow. Accuracy of the nomogram for classifying obstruction was then tested in a group of 144 men with LUTS who underwent an invasive and a noninvasive pressure flow study.
  
  
  RESULTS
  The modified nomogram identified men with obstruction with 68% positive predictive value and 78% negative predictive value. Predictive accuracy could be improved by adding an additional criterion of obstruction, that is maximum urine flow less than 10 ml second, whereby an identifiable 69% of all cases could be classified as obstructed (88% positive predictive value) or not obstructed (86% negative predictive value). In the remaining 31% of patients invasive pressure flow studies would provide additional information, although some results would remain equivocal.
  
  
  CONCLUSIONS
  The proposed nomogram combined with the additional flow rate criterion can classify more than two-thirds of cases without recourse to invasive pressure flow studies. We must now evaluate the usefulness of this classification for the treatment of men with LUTS.
authors.affiliation: Regional Medical Physics Department, Newcastle upon Tyne, United Kingdom. c.j.griffiths@ncl.ac.uk
authors.forename: C J
authors.initials: CJ
authors.lastname: Griffiths
authors.forename: C
authors.initials: C
authors.lastname: Harding
authors.forename: C
authors.initials: C
authors.lastname: Blake
authors.forename: S
authors.initials: S
authors.lastname: McIntosh
authors.forename: M J
authors.initials: MJ
authors.lastname: Drinnan
authors.forename: W A
authors.initials: WA
authors.lastname: Robson
authors.forename: P
authors.initials: P
authors.lastname: Abrams
authors.forename: P D
authors.initials: PD
authors.lastname: Ramsden
authors.forename: R S
authors.initials: RS
authors.lastname: Pickard
mesh_terms: D000368:Aged; D006801:Humans; D008297:Male; D008875:Middle Aged; D049451:Nomograms; D011237:Predictive Value of Tests; D011446:Prospective Studies; D014524:Urethral Obstruction / Q000175:diagnosis; D001743:Urinary Bladder / Q000503:physiopathology*; D001748:Urinary Bladder Neck Obstruction / Q000175:diagnosis* / Q000503:physiopathology; D014555:Urination Disorders / Q000175:diagnosis / Q000503:physiopathology; D014563:Urodynamics