title: Intra-rater and inter-rater reliability of a medical record abstraction study on transition of care after childhood cancer.
abstract: BACKGROUND
  The abstraction of data from medical records is a widespread practice in epidemiological research. However, studies using this means of data collection rarely report reliability. Within the Transition after Childhood Cancer Study (TaCC) which is based on a medical record abstraction, we conducted a second independent abstraction of data with the aim to assess a) intra-rater reliability of one rater at two time points; b) the possible learning effects between these two time points compared to a gold-standard; and c) inter-rater reliability.
  
  
  METHODS
  Within the TaCC study we conducted a systematic medical record abstraction in the 9 Swiss clinics with pediatric oncology wards. In a second phase we selected a subsample of medical records in 3 clinics to conduct a second independent abstraction. We then assessed intra-rater reliability at two time points, the learning effect over time (comparing each rater at two time-points with a gold-standard) and the inter-rater reliability of a selected number of variables. We calculated percentage agreement and Cohen's kappa.
  
  
  RESULTS
  For the assessment of the intra-rater reliability we included 154 records (80 for rater 1; 74 for rater 2). For the inter-rater reliability we could include 70 records. Intra-rater reliability was substantial to excellent (Cohen's kappa 0-6-0.8) with an observed percentage agreement of 75%-95%. In all variables learning effects were observed. Inter-rater reliability was substantial to excellent (Cohen's kappa 0.70-0.83) with high agreement ranging from 86% to 100%.
  
  
  CONCLUSIONS
  Our study showed that data abstracted from medical records are reliable. Investigating intra-rater and inter-rater reliability can give confidence to draw conclusions from the abstracted data and increase data quality by minimizing systematic errors.
authors.affiliation: Department of Health Sciences and Health Policy, University of Lucerne, Lucerne, Switzerland.
authors.forename: Micòl E
authors.initials: ME
authors.lastname: Gianinazzi
authors.affiliation: Department of Health Sciences and Health Policy, University of Lucerne, Lucerne, Switzerland.
authors.forename: Corina S
authors.initials: CS
authors.lastname: Rueegg
authors.affiliation: Pediatric Hematology/Oncology, University Children's Hospital, Bern, Switzerland.
authors.forename: Karin
authors.initials: K
authors.lastname: Zimmerman
authors.affiliation: Swiss Childhood Cancer Registry, Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland.
authors.forename: Claudia E
authors.initials: CE
authors.lastname: Kuehni
authors.affiliation: Department of Health Sciences and Health Policy, University of Lucerne, Lucerne, Switzerland.
authors.forename: Gisela
authors.initials: G
authors.lastname: Michel
mesh_terms: D002648:Child; D003625:Data Collection / Q000592:standards; D006801:Humans; D008499:Medical Records; D009369:Neoplasms; D015588:Observer Variation; D015203:Reproducibility of Results