title: Comparison of fracture risk between patients with ileal pouch-anal anastomosis for ulcerative colitis and the general population.
abstract: BACKGROUND
  Restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA) is the preferred surgical treatment for ulcerative colitis (UC). Little is known of how the operation affects bone metabolism and fracture risk. The aim of this retrospective cohort study was to investigate fracture risk and serum markers of bone metabolism following IPAA in a national cohort of Danish UC patients.
  
  
  METHODS
  Diagnostic codes for 1757 patients and 8785 controls were obtained from the National Patient Register while blood results were collected from a regional database. Postoperative fracture free survival was evaluated on a Kaplan-Meier plot. Fracture hazard ratios (HR) after IPAA were calculated from Cox proportional hazards regression analysis.
  
  
  RESULTS
  Fracture risk after IPAA was significantly reduced (adjusted HR = 0.49, 95% CI: 0.43; 0.55, p<0.001). Prior fractures and alcoholism independently increased fracture risk significantly. Osteoporotic fracture risk after IPAA was reduced, significantly for wrist fractures (aHR = 0.39, 95% CI: 0.22; 0.71, p = 0.002), and borderline insignificantly for spine fractures (aHR = 0.51, 95% CI: 0.26; 1.01, p = 0.054). Vitamin D and calcium levels were significantly higher in the patient group (61.2 nmol/L vs. 58.9 nmol/L, p = 0.04 and 1.24 mmol/L vs. 1.21 mmol/L, p<0.01, respectively), while parathyroid hormone and phosphate levels were significantly lower (4.9 pmol/L vs. 6.2 pmol/L, p<0.01 and 1.08 mmol/L vs. 1.12 mmol/L, p<0.01, respectively).
  
  
  CONCLUSIONS
  Fracture risk after IPAA is significantly reduced compared to the general population. Prospective studies are needed to verify the biochemical results.
authors.affiliation: Colorectal Surgical Unit, Aarhus University Hospital, Tage-Hansens Gade 2, 8000 Århus C, Denmark. Electronic address: anders.mark@studmed.au.dk.
authors.forename: Anders Mark
authors.initials: AM
authors.lastname: Christensen
authors.affiliation: Colorectal Surgical Unit, Aarhus University Hospital, Tage-Hansens Gade 2, 8000 Århus C, Denmark.
authors.forename: Søren
authors.initials: S
authors.lastname: Brandsborg
authors.affiliation: Aalborg University, Aalborg University Hospital, Fredrik Bajersvej 7c, 9220 Aalborg, Denmark.
authors.forename: Peter
authors.initials: P
authors.lastname: Vestergaard
authors.affiliation: Colorectal Surgical Unit, Aarhus University Hospital, Tage-Hansens Gade 2, 8000 Århus C, Denmark.
authors.forename: Søren
authors.initials: S
authors.lastname: Laurberg
mesh_terms: D000293:Adolescent; D000328:Adult; D000437:Alcoholism / Q000453:epidemiology; D000469:Alkaline Phosphatase / Q000097:blood; D001842:Bone and Bones / Q000378:metabolism*; D002118:Calcium / Q000097:blood; D016022:Case-Control Studies; D003093:Colitis, Ulcerative / Q000097:blood* / Q000601:surgery*; D039021:Colonic Pouches; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D058866:Osteoporotic Fractures / Q000453:epidemiology*; D010281:Parathyroid Hormone / Q000097:blood; D010710:Phosphates / Q000097:blood; D015995:Prevalence; D016737:Proctocolectomy, Restorative; D012189:Retrospective Studies; D018570:Risk Assessment; D016103:Spinal Fractures / Q000453:epidemiology; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014954:Wrist Injuries / Q000453:epidemiology; D055815:Young Adult
chemical_list: D010281:Parathyroid Hormone; D010710:Phosphates; D014807:Vitamin D; C104450:25-hydroxyvitamin D; D000469:Alkaline Phosphatase; D002118:Calcium
keywords: Bone metabolism; Fracture risk; Ileal pouch-anal anastomosis; Restorative proctocolectomy; Ulcerative colitis