Impact of unlinked deaths and coding changes on mortality trends in the Swiss National Cohort

BMC Medical Informatics and Decision Making

Research Article

Adrian Spoerri¹  Kurt Schmidlin¹  Matthias Egger²  Marcel Zwahlen³  Kerri M Clough-Gorr⁴ 

[1] Division of International & Environmental Health, Institute of Social and Preventive Medicine (ISPM), University of Bern, Bern, Switzerland;Division of International & Environmental Health, Institute of Social and Preventive Medicine (ISPM), University of Bern, Bern, Switzerland;Department of Social and Community Medicine, University of Bristol, Bristol, UK;Division of International & Environmental Health, Institute of Social and Preventive Medicine (ISPM), University of Bern, Bern, Switzerland;Institute of Social and Preventive Medicine (ISPM, University of Bern, Finkenhubelweg 11, CH-3012, Bern, Switzerland;Division of International & Environmental Health, Institute of Social and Preventive Medicine (ISPM), University of Bern, Bern, Switzerland;National Institute for Cancer Epidemiology and Registration (NICER), Institute of Social and Preventive Medicine (ISPM), University of Zürich, Zürich, Switzerland;Section of Geriatrics, Boston University Medical Center, Boston, MA, USA;

关键词: Cohort studies;    Record linkage;    Mortality;    Trends;   

DOI  :  10.1186/1472-6947-13-1

 received in 2012-07-16, accepted in 2012-12-15,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundResults of epidemiological studies linking census with mortality records may be affected by unlinked deaths and changes in cause of death classification. We examined these issues in the Swiss National Cohort (SNC).MethodsThe SNC is a longitudinal study of the entire Swiss population, based on the 1990 (6.8 million persons) and 2000 (7.3 million persons) censuses. Among 1,053,393 deaths recorded 1991–2007 5.4% could not be linked using stringent probabilistic linkage. We included the unlinked deaths using pragmatic linkages and compared mortality rates for selected causes with official mortality rates. We also examined the impact of the 1995 change in cause of death coding from version 8 (with some additional rules) to version 10 of the International Classification of Diseases (ICD), using Poisson regression models with restricted cubic splines. Finally, we compared results from Cox models including and excluding unlinked deaths of the association of education, marital status, and nationality with selected causes of death.ResultsSNC mortality rates underestimated all cause mortality by 9.6% (range 2.4% - 17.9%) in the 85+ population. Underestimation was less pronounced in years nearer the censuses and in the 75–84 age group. After including 99.7% of unlinked deaths, annual all cause SNC mortality rates were reflecting official rates (relative difference between −1.4% and +1.8%). In the 85+ population the rates for prostate and breast cancer dropped, by 16% and 21% respectively, between 1994 and 1995 coincident with the change in cause of death coding policy. For suicide in males almost no change was observed. Hazard ratios were only negligibly affected by including the unlinked deaths. A sudden decrease in breast (21% less, 95% confidence interval: 12% - 28%) and prostate (16% less, 95% confidence interval: 7% - 23%) cancer mortality rates in the 85+ population coincided with the 1995 change in cause of death coding policy.ConclusionsUnlinked deaths bias analyses of absolute mortality rates downwards but have little effect on relative mortality. To describe time trends of cause-specific mortality in the SNC, accounting for the unlinked deaths and for the possible effect of change in death certificate coding was necessary.

【 授权许可】

Unknown   
© Schmidlin et al.; licensee BioMed Central Ltd. 2013. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.