title: Completeness and validity in a national clinical thyroid cancer database: DATHYRCA.
abstract: BACKGROUND
  Although a prospective national clinical thyroid cancer database (DATHYRCA) has been active in Denmark since January 1, 1996, no assessment of data quality has been performed. The purpose of the study was to evaluate completeness and data validity in the Danish national clinical thyroid cancer database: DATHYRCA.
  
  
  METHODS
  National prospective cohort. Denmark; population 5.5 million. Completeness of case ascertainment was estimated by the independent case ascertainment method using three governmental registries as a reference. The reabstracted record method was used to appraise the validity. For validity assessment 100 cases were randomly selected from the DATHYRCA database; medical records were used as a reference.
  
  
  RESULTS
  The database held 1934 cases of thyroid carcinoma and completeness of case ascertainment was estimated to 90.9%. Completeness of registration was around or above 90% in most instances. Perfect agreement on the diagnosis of thyroid carcinoma was found, both inter- and intra-observer, and κ values of selected variables showed overall good to excellent agreement.
  
  
  CONCLUSIONS
  In a setup with public health insurance, personal identity numbers and extended governmental databases, it is possible to establish national clinical cancer databases with a satisfactory completeness and validity. The DATHYRCA database is considered reliable in terms of describing thyroid carcinoma at a national level.
authors.affiliation: Department of ENT Head & Neck Surgery, Odense University Hospital, Denmark. Electronic address: stefano.londero@ouh.regionsyddanmark.dk.
authors.forename: Stefano Christian
authors.initials: SC
authors.lastname: Londero
authors.affiliation: Department of ENT Head & Neck Surgery, Odense University Hospital, Denmark.
authors.forename: Jes Sloth
authors.initials: JS
authors.lastname: Mathiesen
authors.affiliation: Department of Pathology, Odense University Hospital, Denmark.
authors.forename: Annelise
authors.initials: A
authors.lastname: Krogdahl
authors.affiliation: Department of Oncology, Odense University Hospital, Denmark.
authors.forename: Lars
authors.initials: L
authors.lastname: Bastholt
authors.affiliation: Department of Experimental Clinical Oncology, Aarhus University Hospital, Denmark.
authors.forename: Jens
authors.initials: J
authors.lastname: Overgaard
authors.affiliation: Department of Oncology, Herlev Hospital, Denmark.
authors.forename: Jens
authors.initials: J
authors.lastname: Bentsen
authors.affiliation: Department of ENT Head & Neck Surgery, Copenhagen University Hospital, Denmark.
authors.forename: Christoffer Holst
authors.initials: CH
authors.lastname: Hahn
authors.affiliation: Department of ENT Head & Neck Surgery, Aarhus University Hospital, Denmark.
authors.forename: Sten
authors.initials: S
authors.lastname: Schytte
authors.affiliation: Department of ENT Head & Neck Surgery, Aalborg University Hospital, Denmark.
authors.forename: Henrik Baymler
authors.initials: HB
authors.lastname: Pedersen
authors.affiliation: Department of Surgery, Aarhus University Hospital, Denmark.
authors.forename: Peer
authors.initials: P
authors.lastname: Christiansen
authors.affiliation: Department of ENT Head & Neck Surgery, Odense University Hospital, Denmark.
authors.forename: Christian
authors.initials: C
authors.lastname: Godballe
mesh_terms: D015331:Cohort Studies; D016208:Databases, Factual / Q000592:standards* / Q000706:statistics & numerical data; D003718:Denmark / Q000453:epidemiology; D006801:Humans; D011446:Prospective Studies; D012042:Registries; D013964:Thyroid Neoplasms / Q000453:epidemiology* / Q000473:pathology
keywords: Agreement; Completeness; Database; Epidemiology; National registry; Thyroid carcinoma; Validation; Validity