title: Predictors of outcome of anorectal biofeedback therapy in patients with constipation.
abstract: BACKGROUND
  Anorectal biofeedback therapy (BFT) is a safe and effective treatment in patients with constipation. Given the high prevalence of constipation and therefore high demand for BFT, there is a need to prioritise patients.
  
  
  OBJECTIVE
  To explore clinical features and anorectal physiology which predict success or failure of BFT and to derive a statistical model which helps to predict the success of BFT.
  
  
  METHODS
  A total of 102 patients with constipation referred for BFT were evaluated. All patients underwent comprehensive clinical and anorectal function assessment, including balloon expulsion testing. The BFT protocol consisted of a comprehensive 6-weekly visit programme comprising instruction on toilet behaviour and abdominal breathing, achieving adequate rectal pressure and anal relaxation, and balloon expulsion and rectal sensory retraining. Success of BFT was based on an improvement in global bowel satisfaction.
  
  
  RESULTS
  Harder stool consistency (P=0.009), greater willingness to participate (P<0.001), higher resting anal sphincter pressure (P=0.04) and prolonged balloon expulsion time (P=0.02) correlated with an improvement in bowel satisfaction score. A longer duration of laxative use (P=0.049) correlated with no improvement in bowel satisfaction score. Harder stools, shorter duration of laxative use, higher straining rectal pressure and prolonged balloon expulsion independently predicted successful BFT. A model (S(i) = (p)∑ β(j)X(ij), where β represents a regression coefficient, X is a given predictive variable and S(i) is the weighted index score for each individual) incorporating these four variables enabled prediction of successful BFT, with sensitivity and specificity of 0.79 and 0.81, respectively.
  
  
  CONCLUSIONS
  Important clinical and anorectal physiological features were found to be associated with outcome of anorectal biofeedback therapy in patients with constipation. This information and the predictive model will assist clinicians to prioritise patients for anorectal biofeedback therapy.
authors.affiliation: Gastrointestinal Investigation Unit, Royal North Shore Hospital and University of Sydney, Sydney, NSW, Australia.
authors.forename: L S E
authors.initials: LS
authors.lastname: Shim
authors.forename: M
authors.initials: M
authors.lastname: Jones
authors.forename: G M
authors.initials: GM
authors.lastname: Prott
authors.forename: L I
authors.initials: LI
authors.lastname: Morris
authors.forename: J E
authors.initials: JE
authors.lastname: Kellow
authors.forename: A
authors.initials: A
authors.lastname: Malcolm
mesh_terms: D001003:Anal Canal; D001676:Biofeedback, Psychology / Q000379:methods*; D003248:Constipation / Q000628:therapy*; D003672:Defecation / Q000502:physiology; D005260:Female; D005772:Gastrointestinal Transit / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D017060:Patient Satisfaction; D012007:Rectum; D012044:Regression Analysis; D016896:Treatment Outcome