title: Assessing the activity of perianal Crohn's disease: comparison of clinical indices and computer-assisted anal ultrasound.
abstract: BACKGROUND
  Assessing perianal disease activity is important for the treatment and prognosis of Crohn's disease (CD) patients, but the diagnostic accuracy of the activity indices has not yet been established. The aim of this study was to determine the accuracy and agreement of the Fistula Drainage Assessment (FDA), Perianal Disease Activity Index (PDAI), and computer-assisted anal ultrasound imaging (AUS).
  
  
  METHODS
  Sixty-two consecutive patients with CD and perianal fistulae underwent clinical, FDA, PDAI, and AUS evaluation. Perianal disease was considered active in the presence of visible fistula drainage and/or signs of local inflammation (induration and pain at digital compression) upon clinical examination. The AUS images were analyzed by calculating the mean gray-scale tone of the lesion. The PDAI and gray-scale tone values discriminating active and inactive perianal disease were defined using receiver operating characteristics statistics.
  
  
  RESULTS
  Perianal disease was active in 46 patients. The accuracy of the FDA was 87% (confidence interval [CI]: 76%-94%). A PDAI of >4 and a mean gray-scale tone value of 117 maximized sensitivity and specificity; their diagnostic accuracy was, respectively, 87% (CI: 76%-94%) and 81% (CI: 69%-90%). The agreement of the 3 evaluations was fair to moderate. The addition of AUS to the PDAI or FDA increased their diagnostic accuracy to respectively 95% and 98%.
  
  
  CONCLUSIONS
  The diagnostic accuracy of the FDA, PDAI, and computer-assisted AUS imaging was good in assessing perianal disease activity in patients with CD. The agreement between the techniques was fair to moderate. Overall accuracy can be increased by combining the FDA or PDAI with AUS.
authors.affiliation: Postgraduate School of Gastroenterology, University of Milan, Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Milan, Italy. alessandra.losco@unimi.it
authors.forename: Alessandra
authors.initials: A
authors.lastname: Losco
authors.forename: Chiara
authors.initials: C
authors.lastname: Viganò
authors.forename: Dario
authors.initials: D
authors.lastname: Conte
authors.forename: Bruno Mario
authors.initials: BM
authors.lastname: Cesana
authors.forename: Guido
authors.initials: G
authors.lastname: Basilisco
mesh_terms: D000328:Adult; D000368:Aged; D001004:Anus Diseases / Q000000981:diagnostic imaging*; D003424:Crohn Disease / Q000000981:diagnostic imaging*; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008875:Middle Aged; D012003:Rectal Fistula / Q000000981:diagnostic imaging*; D012680:Sensitivity and Specificity; D014463:Ultrasonography; D014481:United States; D014486:United States Food and Drug Administration