title: Validating the British Columbia Perinatal Data Registry: a chart re-abstraction study.
abstract: BACKGROUND
  The British Columbia Perinatal Data Registry (BCPDR) contains individual-level obstetrical and neonatal medical chart data for virtually all births occurring in British Columbia, Canada. The objective of this study was to assess the validity of information in the BCPDR by performing a provincial chart re-abstraction study.
  
  
  METHODS
  A two-stage stratified clustered sampling design was employed. Obstetrical facilities were stratified based on geographic location and obstetrical volume. Charts of mothers and newborns with a length of stay of five or more days or transfer to another facility following the delivery were oversampled. A total of 85 maternal and 32 newborn variables were assessed for completeness (percent completion) and validity (sensitivity and specificity for categorical variables, intra-class correlation coefficient [ICC] for continuous variables).
  
  
  RESULTS
  1,084 maternal and 1,142 newborn charts were abstracted. Mandatory variables such as primary indication for induction and primary indication for cesarean delivery were 100 % complete. Some variables such as pre-pregnancy weight were relatively more complete in the re-abstraction as compared with the BCPDR (83.0 % vs 76.8 %; p < 0.001). The validity of key surveillance variables was high (e.g., HIV screening completed [sensitivity 98.0 %, 95 % confidence interval (CI) 97.0-98.8 %; specificity 72.3 %, 95 % CI 60.8-81.9 %], induction of labour [sensitivity 93.9 %, 95 % CI 90.2-96.5 %; specificity 98.7 %, 95 % CI 97.7-99.3 %], primary elective cesarean delivery [sensitivity 96.0 %, 95 % CI 83.8-99.7 %; specificity 99.8 %, 95 % CI 99.4-100.0 %], gestational age from newborn examination [ICC 0.99, 95 % CI 0.99-0.99]). Examples of variables with lower validity included total admissions prior to delivery episode, maternal smoking status, and timing of breastfeeding initiation.
  
  
  CONCLUSIONS
  Many important clinical and population health variables in the BCPDR had excellent validity. Some key variables warrant strengthening through improved definitions, system changes, and abstractor training.
authors.affiliation: Perinatal Services BC, West Tower, 3rd Floor, 555 West 12th Avenue, Vancouver, British Columbia, Canada, V5Z 3X7. Gillian.Frosst@interiorhealth.ca.
authors.forename: Gillian
authors.initials: G
authors.lastname: Frosst
authors.affiliation: Perinatal Services BC, West Tower, 3rd Floor, 555 West 12th Avenue, Vancouver, British Columbia, Canada, V5Z 3X7. jhutcheon@cfri.ca.|Department of Obstetrics and Gynaecology, University of British Columbia, Shaughnessy Building C420, BC Children's and Women's Hospital, 4500 Oak Street, Vancouver, British Columbia, Canada, V6H 3N1. jhutcheon@cfri.ca.|School of Population and Public Health, University of British Columbia, 2206 East Mall, Vancouver, British Columbia, Canada, V6T 1Z3. jhutcheon@cfri.ca.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Hutcheon
authors.affiliation: Department of Obstetrics and Gynaecology, University of British Columbia, Shaughnessy Building C420, BC Children's and Women's Hospital, 4500 Oak Street, Vancouver, British Columbia, Canada, V6H 3N1. Ksjoseph@cfri.ca.|School of Population and Public Health, University of British Columbia, 2206 East Mall, Vancouver, British Columbia, Canada, V6T 1Z3. Ksjoseph@cfri.ca.
authors.forename: K S
authors.initials: KS
authors.lastname: Joseph
authors.affiliation: Perinatal Services BC, West Tower, 3rd Floor, 555 West 12th Avenue, Vancouver, British Columbia, Canada, V5Z 3X7. Bkinniburgh@phsa.ca.
authors.forename: Brooke
authors.initials: B
authors.lastname: Kinniburgh
authors.affiliation: Perinatal Services BC, West Tower, 3rd Floor, 555 West 12th Avenue, Vancouver, British Columbia, Canada, V5Z 3X7. cjohnson@phsa.ca.
authors.forename: Cathe
authors.initials: C
authors.lastname: Johnson
authors.affiliation: Perinatal Services BC, West Tower, 3rd Floor, 555 West 12th Avenue, Vancouver, British Columbia, Canada, V5Z 3X7. lily.lee@phsa.ca.
authors.forename: Lily
authors.initials: L
authors.lastname: Lee
mesh_terms: D000328:Adult; D001955:British Columbia; D016000:Cluster Analysis; D036861:Delivery, Obstetric / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D000068104:Infant Health / Q000706:statistics & numerical data*; D007231:Infant, Newborn; D000068097:Maternal Health / Q000706:statistics & numerical data*; D008499:Medical Records / Q000706:statistics & numerical data*; D018743:Perinatal Care / Q000706:statistics & numerical data*; D011247:Pregnancy; D012042:Registries / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity