Data quality at the Cancer Registry of Norway: An overview of comparability, completeness, validity and timeliness
Introduction
The reporting of neoplasms (and certain precancerous lesions) to the Cancer Registry of Norway (CRN) has been compulsory following a directive from the Ministry of Health and Social Affairs in 1951. A Health Registry Act came into force in 2002 that included statutory regulations for the CRN,1 strengthening the legal obligation to report new precancerous and cancerous cases, and requiring all hospitals, laboratories and general practitioners in Norway to report these cases. This legislation, the efficient reporting from multiple sources and the trace-back routines have been built up at the Registry over the last decades.
Several studies at the regional2 and site-specific level3, 4, 5 have reported an overall estimated of completeness at the CRN at greater than 95%. An overview of these studies is given in the Appendix. An evaluation of the data quality at CRN was recently included as a special issue of the Registry’s annual report Cancer in Norway.6 Selected results from that evaluation are elaborated and discussed in this paper.
The overall aim of this study is to provide a comprehensive evaluation of the data quality of the data at the CRN for all cancer types, applying the principles and techniques of evaluation described in the accompanying reports on data quality methods in this issue.7, 8
Section snippets
Sources of information in the Cancer Registry of Norway
Hospitals, pathological laboratories, general practitioners and the National Statistics Office (Statistics Norway) provide the key information that enables the CRN to collect, code and store data on cancer patients in Norway. Clinical notifications are reported on structured templates with one form for solid cancers and another for non-solid tumours. Information is sought on localisation, the extent of the disease and treatment on these forms. In addition, some site-specific forms with
Methods
A brief overview of the subset of techniques covered by Bray and Parkin and Parkin and Bray7, 8 that have been applied to the data from the CRN is set out below, together with a specification of the relevant time periods used for each method.
Comparability
Incident cases in Norway comprise all malignant and in situ neoplasms, and the incidence reported in Cancer in Norway (CiN) includes all cases with the 5th-digit behaviour code 3 according to ICD-O-3, for haematological malignancies, and ICD-O-2, for other tumours. Cases with 5th-digit behaviour code 1 are also included for tumours of the central nervous system.
Fig. 1 gives an overview of the international standards that have been followed11, 12, 13, 14, 15, 16 for the classification and coding
Discussion
The prerequisites for population-based high quality cancer incidence data are favourable in Norway with mandatory reporting, unique personal identification numbers and more than 50 years of experience in cancer registration. The present evaluation of the quality of data supports the notion that the Registry has a high degree of comparability, completeness, accuracy and timeliness. Some heterogeneity was, however, observed for some quality indicators for specific cancer sites. Cancers of the
Conclusion
This review indicated that the routines in place at the CRN yield comparable data that can be considered reasonably accurate, close-to-complete and timely, and serves as a justification for our policy of reporting annual incidence one year after the close of registration.
Conflict of interest statement
None declared.
Authors contribution
Study concept and design: FB, DMP, BM
Acquisition of data: IKL
Analysis and interpretation of data: IKL, MS
Drafting of the manuscript: IKL, BM, MS, TBJ
Critical revision of the manuscript for important intellectual content: IKL, MS, TBJ, FL, DMP, FB, BM.
Acknowledgements
We would like to thank the following staffs at the Cancer Registry of Norway for discussion and comment: Aage Johansen, Bjørge Sæther, Svein Erling Tysvær, Tove Dahl, Siri Larønningen, Olaug Talleraas and Christine Mellem. This study was undertaken as part of the Cancer Control using Population-based Registries and Biobanks (CCPRB) project, funded by the EU Sixth Framework Programme (FP6-2002-LifeSciHealth Contract No. 503465).
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