title: Validity of the Danish National Registry of Patients for chemotherapy reporting among colorectal cancer patients is high.
abstract: BACKGROUND
  The Danish National Registry of Patients (DNRP) is a potentially valuable resource for monitoring national trends in the use of chemotherapy and evaluating the benefits and harms of alternative treatments among colorectal cancer (CRC) patients in Denmark. However, the validity of chemotherapy reporting in the DNRP is unknown. In this study, we evaluated the validity of the DNRP for identifying the receipt of chemotherapy and specific treatments, and the timing and number of treatments among CRC patients, using medical records and pharmacy data as the reference standard.
  
  
  METHODS
  We selected a random sample of CRC patients with lymph node involvement who were diagnosed at Aarhus University Hospital (n = 25) or Aalborg University Hospital (n = 25) from 2009 to 2010. Administration dates, specific treatments, and number of treatment courses were abstracted for the 180 days post diagnosis from the DNRP, medical records, and pharmacy production databases. The prevalence of chemotherapy, timing of first administration, and number of courses were described. DNRP data were compared with the reference standard for each hospital, and the kappa, sensitivity, specificity, positive and negative predictive values, and 95% confidence intervals were calculated for the receipt of any chemotherapy and specific treatments.
  
  
  RESULTS
  The prevalence of chemotherapy was 72% and 68% among CRC patients treated in Aarhus and Aalborg, respectively, with >90% of patients without distant metastasis receiving treatment within 90 days from diagnosis. Patients received on average 4.6 and 4.7 treatment courses in Aarhus and Aalborg, respectively. Kappa, sensitivity, and specificity of chemotherapy reporting in the DNRP was high (≥0.88), but the sensitivity of individual chemotherapies varied by hospital.
  
  
  CONCLUSIONS
  The validity of chemotherapy reporting in the DNRP was high, although some variation by hospital exists. The DNRP represents a population-based nationwide resource that can be used to provide timely and accurate evaluations of chemotherapy use among CRC patients in Denmark.
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Lund
authors.forename: Trine
authors.initials: T
authors.lastname: Frøslev
authors.forename: Thomas
authors.initials: T
authors.lastname: Deleuran
authors.forename: Rune
authors.initials: R
authors.lastname: Erichsen
authors.forename: Tove
authors.initials: T
authors.lastname: Nilsson
authors.forename: Annette Nørkær
authors.initials: AN
authors.lastname: Pedersen
authors.forename: Morten
authors.initials: M
authors.lastname: Høyer
keywords: administrative data; chemotherapy; colorectal cancer
references.citation: J Clin Oncol. 2012 Jul 20;30(21):2624-34
references.pmid: 22665536
references.citation: J Natl Cancer Inst. 2006 May 3;98(9):610-9
references.pmid: 16670386
references.citation: Cancer. 2012 Sep 1;118(17):4309-20
references.pmid: 22294436
references.citation: J Natl Cancer Inst. 2012 Feb 8;104(3):211-27
references.pmid: 22266473
references.citation: Med Care. 2013 May;51(5):e27-34
references.pmid: 22080337
references.citation: N Engl J Med. 2004 Jun 3;350(23):2335-42
references.pmid: 15175435
references.citation: Eur J Cancer Care (Engl). 2012 Nov;21(6):722-7
references.pmid: 22510213
references.citation: Cancer. 2013 Jun 1;119(11):2038-47
references.pmid: 23512326
references.citation: Clin Epidemiol. 2012;4 Suppl 2:33-8
references.pmid: 23115791
references.citation: N Engl J Med. 2004 Jun 3;350(23):2343-51
references.pmid: 15175436
references.citation: JAMA. 2004 Jun 9;291(22):2720-6
references.pmid: 15187053
references.citation: Pharmacoepidemiol Drug Saf. 2013 Aug;22(8):810-8
references.pmid: 23296544
references.citation: Science. 2000 Mar 31;287(5462):2398-9
references.pmid: 10766613
references.citation: Med Care. 2002 Aug;40(8 Suppl):IV-55-61
references.pmid: 12187169