title: The rate of obstetric anal sphincter injuries in Finnish obstetric units as a patient safety indicator.
abstract: OBJECTIVE
  To study whether there are significant differences in the rate of obstetric anal sphincter injuries (OASIS) between the different sized delivery units in Finland.
  
  
  METHODS
  The study was performed as a population based registry study in Finland, including all births (294725) between 2006 and 2010. All the Finnish delivery units (34) were categorized by the number of annual deliveries and the OASIS rate was then compared between the different sized delivery units using a logistic regression analysis adjusting for maternal age and parity. The Robson ten group classification was used for more accurate comparison.
  
  
  RESULTS
  The OASIS rate was significantly elevated, both in the largest units with 5000 annual deliveries or more (OR 1.46, 95% CI 1.11-1.92) and in the smallest units with less than 500 annual deliveries (OR 1.33, 95% CI 1.22-1.45). In the Robson's group 1 (primiparous, single cephalic term pregnancy, spontaneous labour) the risk for OASIS was the highest in the largest units (OR 1.44, 95% CI 1.28-1.61) while in the Robson's group 3 (multiparous, single cephalic term pregnancy, spontaneous labour) the highest risk was found in the smallest units (OR 2.90, 95% CI 1.68-5.02).
  
  
  CONCLUSIONS
  There is significant inter-hospital variation in OASIS rates suggesting significant differences in obstetric practices. Robson's ten group classification should be used to enhance the inter-hospital comparison.
authors.affiliation: Department of Obstetrics and Gynaecology, Helsinki University Hospital, PO Box 140, FIN-00029 HUS, Finland. aura.pyykonen@helsinki.fi
authors.forename: Aura
authors.initials: A
authors.lastname: Pyykönen
authors.forename: Mika
authors.initials: M
authors.lastname: Gissler
authors.forename: Maija
authors.initials: M
authors.lastname: Jakobsson
authors.forename: Lasse
authors.initials: L
authors.lastname: Lehtonen
authors.forename: Anna-Maija
authors.initials: AM
authors.lastname: Tapper
mesh_terms: D001003:Anal Canal / Q000293:injuries*; D003696:Delivery Rooms / Q000706:statistics & numerical data*; D036861:Delivery, Obstetric / Q000009:adverse effects; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D016015:Logistic Models; D008423:Maternal Age; D007744:Obstetric Labor Complications / Q000453:epidemiology*; D010298:Parity; D061214:Patient Safety / Q000706:statistics & numerical data*; D011247:Pregnancy