title: Development and validation of visceral fat quantification as a surrogate marker for differentiation of Crohn's disease and intestinal tuberculosis.
abstract: OBJECTIVE
  Crohn's disease (CD) and intestinal tuberculosis (ITB) have close phenotypic resemblance. Mesenteric fat (a component of visceral fat [VF]) hypertrophy and fat wrapping, which is visible radiologically as fibrofatty proliferation, is seen more commonly in CD than in ITB.
  
  
  OBJECTIVE
  The present study was conducted to study the role of VF in differentiating CD and ITB.
  
  
  METHODS
  Visceral fat area and subcutaneous (SC) fat area were measured on computed tomography in two cohorts (development and validation). VF/SC ratio was also calculated for all patients. In the development cohort, retrospective data collection was carried out for 75 patients with CD and ITB who were on follow-up from January 2012 to November 2014. In the validation cohort, 82 patients were recruited prospectively from December 2014 to December 2015 and were diagnosed as CD or ITB according to standard diagnostic criteria.
  
  
  RESULTS
  Visceral fat area and VF/SC ratio were significantly higher in CD patients (n = 42: development, n = 46: validation) than in ITB patients (n = 33: development, n = 36: validation) in both the development (106.2 ± 63.5 vs 37.3 ± 22, P = <0.001; 1.1 ± 0.57 vs 0.43 ± 0.24, P = <0.001) and validation cohorts (102.2 ± 69.8 vs 55.8 ± 44.9, P = 0.01; 1.2 ± 0.68 vs 0.56 ± 0.33, P = <0.001). A cut-off of 0.63 for VF/SC ratio in the development cohort had a high sensitivity (82%) and specificity (81%) in differentiating CD and ITB. Similar sensitivity (81%) and specificity (78%) were seen when this cut-off was applied in the validation cohort.
  
  
  CONCLUSIONS
  The VF/SC ratio is a simple, cost-effective, non-invasive and single objective parameter with a good sensitivity and specificity to differentiate CD and ITB.
authors.affiliation: Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Dawesh Prakash
authors.initials: DP
authors.lastname: Yadav
authors.affiliation: Department of Radiodiagnosis, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Kumble Seetharama
authors.initials: KS
authors.lastname: Madhusudhan
authors.affiliation: Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Saurabh
authors.initials: S
authors.lastname: Kedia
authors.affiliation: Department of Radiodiagnosis, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Raju
authors.initials: R
authors.lastname: Sharma
authors.affiliation: Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Venigalla
authors.initials: V
authors.lastname: Pratap Mouli
authors.affiliation: Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Sawan
authors.initials: S
authors.lastname: Bopanna
authors.affiliation: Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Rajan
authors.initials: R
authors.lastname: Dhingra
authors.affiliation: Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Rajesh
authors.initials: R
authors.lastname: Pradhan
authors.affiliation: Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Goyal
authors.affiliation: Department of Biostatistics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Vishnubhatla
authors.initials: V
authors.lastname: Sreenivas
authors.affiliation: Department of Medicine, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Naval K
authors.initials: NK
authors.lastname: Vikram
authors.affiliation: Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Govind
authors.initials: G
authors.lastname: Makharia
authors.affiliation: Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Vineet
authors.initials: V
authors.lastname: Ahuja
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers; D015331:Cohort Studies; D003424:Crohn Disease / Q000175:diagnosis*; D003625:Data Collection; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D050152:Intra-Abdominal Fat / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D050151:Subcutaneous Fat / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed; D014385:Tuberculosis, Gastrointestinal / Q000175:diagnosis*; D055815:Young Adult
chemical_list: D015415:Biomarkers
keywords: CT; Crohn's disease; intestinal tuberculosis; visceral fat