title: Trends in cholecystectomy rates in a defined population during and after the period of transition from open to laparoscopic surgery.
abstract: OBJECTIVE
  To evaluate cholecystectomy rates in a Norwegian county during the transition time from open to laparoscopic surgery, with focus on the incident rate of laparoscopic operations, sex differences, age at operation, and indications for cholecystectomy.
  
  
  METHODS
  All 2615 patients living in North Trondelag County and operated with cholecystectomy for benign biliary disease between 1990 and 2011 were identified. Poisson regression was used to analyze factors associated with cholecystectomy incidence rate ratios (IRRs).
  
  
  RESULTS
  The proportion of completed laparoscopic cholecystectomies was 8% in 1992, 50% in 1994, 94% in 2003 and 99% in 2011. The incidence of cholecystectomy increased from 6.2 per 10 000 person-years in 1990-1992, 8.0 in 1993-1997, to 10.0 in 1998-2003 and remained at this level with a rate of 10.7 during 2004-2011. Adjusting for age at each year of surgery the IRR for females compared with males was 2.3(2.1-2.5) p < 0.001. The median age at operation was 60.2 years (13-90) in males, 50.1 years (12-93) in females p < 0.001. The median age diminished by 5 years in both males and females. A conversion from laparoscopic to open surgery decreased significantly by calendar year of surgery, increased with age of the patient, and was less often in surgery for gallstone colic than for other indications.
  
  
  CONCLUSIONS
  During the introduction of laparoscopic surgery, the rates of cholecystectomy increased and remained stable at a higher level during the later years of the study. The rate of completed laparoscopic operations increased from 8% in 1992 to 99% in 2011.
authors.affiliation: Department of Surgery, Levanger Hospital, Nord-Trøndelag Health Trust , Levanger , Norway.
authors.forename: Arne
authors.initials: A
authors.lastname: Talseth
authors.forename: Stian
authors.initials: S
authors.lastname: Lydersen
authors.forename: Finnegil
authors.initials: F
authors.lastname: Skjedlestad
authors.forename: Kristian
authors.initials: K
authors.lastname: Hveem
authors.forename: Tom-Harald
authors.initials: TH
authors.lastname: Edna
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002763:Cholecystectomy / Q000706:statistics & numerical data / Q000639:trends; D017081:Cholecystectomy, Laparoscopic / Q000706:statistics & numerical data / Q000639:trends*; D041881:Cholecystitis, Acute / Q000601:surgery; D003085:Colic / Q000601:surgery*; D005260:Female; D042882:Gallstones / Q000601:surgery*; D006801:Humans; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D009664:Norway; D012737:Sex Factors; D055815:Young Adult