Extrapolation put into perspective
Recently, our article entitled 'Effect of smoke-free legislation on the incidence of sudden circulatory arrest in the Netherlands' was published in Heart, in which we investigated sudden circulatory arrest (SCA) incidence trends before and after introduction of smoke-free legislation (1). We found a significant decrease in incidence trend after introduction of a nationwide workplace smoking ban.
Because (changes in) trends are difficult to interpret, we illustrated our study results by estimating the absolute reduction of SCA cases after 1 year of smoke-free legislation in our study population (inhabitants of South Limburg between 20 and 75 years of age). In the discussion section of our article we additionally extrapolated our regional findings to the Netherlands as a whole and over a longer period of time. Although this was only a minor issue in the paper, we feel that we have not adequately addressed the assumptions underlying this extrapolation. With this response we would like to put things into perspective.
First, the South Limburg population may not be representative for the whole Dutch population. Second, we erroneously extrapolated to the entire Dutch population, while we should have taken into account only Dutch citizens between 20 and 75 years of age. This would have led to a lower estimate of prevented SCA cases. Third, calculating the absolute reduction of SCA cases over a longer period (4.5 years; the period between introduction of the first (2004) and second (2008) smoking ban) may have resulted in a less precise estimate. For these reasons, the extrapolation should be interpreted with caution. We hope to have clarified this matter sufficiently with this response.
On behalf of all co-authors,
Dianne de Korte-de Boer Maastricht University, the Netherlands
Reference 1. De Korte-de Boer D, Kotz D, Viechtbauer W, et al. Effect of smoke-free legislation on the incidence of sudden circulatory arrest in the Netherlands. Heart 2012;98:995-9.
Conflict of Interest:
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