title: Screening for osteoporosis in Crohn's disease. A detailed evaluation of calcaneal ultrasound.
abstract: OBJECTIVE
  To compare calcaneal broadband ultrasonic attenuation (BUA) and velocity of sound (VOS) in patients with Crohn's disease with an age-matched control population. The validity of BUA as a screening tool for osteoporosis was evaluated and the relationship between BUA and previous fracture studied.
  
  
  METHODS
  Cross-sectional study.
  
  
  BACKGROUND
  Since patients with Crohn's disease are at risk of osteoporosis and premature fracture, routine assessment of bone mineral density (BMD) is recommended. Quantitative ultrasound of the calcaneum is an inexpensive and radiation-free means of assessing bone density which also provides information on bone microstructure.
  
  
  METHODS
  BUA (dB/MHz) and VOS (m/s) were measured at the calcaneum (CUBAclinical, McCue Ultrasonics, Winchester, UK) and compared with bone mineral density at the hip and lumbar spine measured by dual-energy X-ray absorptiometry (DEXA); 100 patients (42 men) with Crohn's disease and 52 age-matched healthy controls (23 men) were studied.
  
  
  RESULTS
  BUA was significantly reduced in patients with Crohn's disease compared with age-matched controls [76.53 dB/MHz (+/-17.3) vs 87.29 dB/MHz (+/-17.9), difference in means = 10.76, 95% CI -16.67, -4.85, P = 0.0004] and was significantly associated with BMD at the spine (r = 0.49, 95% CI 0.32, 0.63, P< 0.0001) and femoral neck (r = 0.54, 95% CI 0.38, 0.67, P < 0.0001). In the diagnosis of osteoporosis (t score <-2.5) BUA had a sensitivity of 66.7% at the femoral neck, with a specificity of 85.6%; sensitivity of BUA at the spine was 75% with specificity 89%.
  
  
  CONCLUSIONS
  Patients with Crohn's disease have reduced BUA compared with an age-matched control population. Calcaneal BUA is significantly associated with BMD at the hip and spine but the correlation is insufficient to recommend ultrasound as a screening tool for DEXA.
authors.affiliation: Gastrointestinal Research Unit, Leicester General Hospital, UK.
authors.forename: R J
authors.initials: RJ
authors.lastname: Robinson
authors.forename: I
authors.initials: I
authors.lastname: Carr
authors.forename: S J
authors.initials: SJ
authors.lastname: Iqbal
authors.forename: F
authors.initials: F
authors.lastname: al-Azzawi
authors.forename: K
authors.initials: K
authors.lastname: Abrams
authors.forename: J F
authors.initials: JF
authors.lastname: Mayberry
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D015519:Bone Density; D002111:Calcaneus / Q000000981:diagnostic imaging*; D003424:Crohn Disease / Q000175:diagnosis*; D005069:Evaluation Studies as Topic; D005260:Female; D005272:Femur Neck / Q000000981:diagnostic imaging; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000517:prevention & control*; D014463:Ultrasonography