Article Text
Abstract
Introduction The International Cancer Benchmarking Partnership (ICBP) identified significant international differences in lung cancer survival. Differing levels of comorbid disease across ICBP countries has been suggested as a potential explanation of this variation but, to date, no studies have quantified its impact. This study investigated whether comparable, robust comorbidity scores can be derived from the different routine population-based cancer data sets available in the ICBP jurisdictions and, if so, use them to quantify international variation in comorbidity and determine its influence on outcome.
Methods Linked population-based lung cancer registry and hospital discharge data sets were acquired from nine ICBP jurisdictions in Australia, Canada, Norway and the UK providing a study population of 233 981 individuals. For each person in this cohort Charlson, Elixhauser and inpatient bed day Comorbidity Scores were derived relating to the 4–36 months prior to their lung cancer diagnosis. The scores were then compared to assess their validity and feasibility of use in international survival comparisons.
Results It was feasible to generate the three comorbidity scores for each jurisdiction, which were found to have good content, face and concurrent validity. Predictive validity was limited and there was evidence that the reliability was questionable.
Conclusion The results presented here indicate that interjurisdictional comparability of recorded comorbidity was limited due to probable differences in coding and hospital admission practices in each area. Before the contribution of comorbidity on international differences in cancer survival can be investigated an internationally harmonised comorbidity index is required.
- Lung cancer
- Clinical epidemiology
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Footnotes
Contributors All authors have contributed to the conception or design of the work; or the acquisition, analysis, or interpretation of data for the work. All authors have been involved in drafting the work or revising it critically for important intellectual content, and have approved of the final version to be published. Finally, all authors agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
Funding This study was supported primarily by NHS England, with additional contributions from Cancer Control Alberta, Cancer Institute NSW, Norwegian Directorate of Health, Cancer Care Ontario, Scottish Government, Cancer Council Victoria, Public Health Wales, Tenovus Cancer Care, Northern Ireland Cancer Registry, the Public Health Agency for Northern Ireland and the Danish Cancer Society.
Competing interests None declared.
Ethics approval The study protocol and the project’s secure data management system were approved by the North West Liverpool Central Research Ethics Committee (14/NW/1372). In addition, each participating registry also obtained the necessary ethical approvals required for participation and data sharing in their jurisdiction via their relevant Research Ethics and Information Governance bodies. Details of these approvals are available on request.
Provenance and peer review Not commissioned; externally peer reviewed.
Correction notice This article has been corrected since it was published Online First. A number of issues were corrected: 1) Authors' Luc te Marvelde and Bjørn Møller names were amended; 2) Figure 3 has been replaced it now has the missing legend included; 3) Data within Table 4 has been corrected; 4) Errors within the references list has been corrected.