title: Diagnosis and grading of detrusor instability using a computerized algorithm.
abstract: OBJECTIVE
  Detrusor instability and hyperreflexia are characterized by involuntary detrusor contractions in the filling phase of the voiding cycle. The diagnosis is made when urodynamic evaluation reveals such contractions. To compare patients and evaluate treatment a method is needed to quantify the degree of instability. We developed an instability parameter based on the area under the curve of involuntary detrusor contractions on conventional filling cystometry.
  
  
  METHODS
  We developed an automatic method to calculate the area under the curve of involuntary detrusor contractions in conventional filling cystometry. Logistic regression was used to construct decision rules to differentiate stable from unstable bladders. These rules, derived from a group of 100 children, were applied to a second group of 77 who were independently assessed by 3 urodynamics experts.
  
  
  RESULTS
  Typically 88% of the second group were correctly classified as stable or unstable by the automatic procedure. In the unstable subgroup there was poor correlation between the calculated instability parameter and the instability score assigned by the experts. Most likely this difference occurred because the experts based their opinion mainly on the amplitude of the highest unstable contraction and the percentage of filling time that instability was found.
  
  
  CONCLUSIONS
  The proposed method of automatically grading detrusor instability based on the area under detrusor contractions differs from the intuitive method used by experts. Since no standard is available, it cannot be concluded which method is better. Our proposed method is objective and it results in a single physical value.
authors.affiliation: Department of Urology (Urodynamics), Erasmus University Rotterdam, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Groen
authors.forename: A J
authors.initials: AJ
authors.lastname: Klijn
authors.forename: J L
authors.initials: JL
authors.lastname: Bosch
authors.forename: J M
authors.initials: JM
authors.lastname: Nijman
authors.forename: R
authors.initials: R
authors.lastname: van Mastrigt
mesh_terms: D000465:Algorithms; D002648:Child; D003697:Delphi Technique; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D011312:Pressure; D012021:Reflex, Abnormal / Q000502:physiology*; D001743:Urinary Bladder / Q000503:physiopathology*; D014563:Urodynamics