Projections of COPD in males in the Netherlands

To the Editors:

In a recent issue of the European Respiratory Journal, projections for a large increase in chronic obstructive pulmonary disease (COPD) in females in the Netherlands up to 2025 were recorded in the study by Hoogendoorn et al. 1. These are depressing, but expected given recent observed trends and the modest changes in smoking made by Dutch females since 1980 2, 3. However, males in the Netherlands, who had the highest known usage of tobacco products per adult of any country from the 1930s to the 1950s 2, have considerably reduced their cigarette consumption since the 1970s 2, 3. Therefore, it is disconcerting to see that continuing upward trends in COPD, albeit smaller in scale, are also projected for Dutch males. Where the predicted time trend is shown 1, there is little, if any, slowing of the rate of increase over the whole period up to 2025. In contrast, according to the World Health Organization (WHO) compilation of national statistics presented by Peto et al. 4, total deaths from lung cancer have recently begun to fall in males within the European Union. In the Netherlands, total male deaths from lung cancer and rates per 100,000 in both the total adult population, and those aged 75–79 yrs, all declined progressively between 1985 and 2000. As discussed in the accompanying editorial by Mannino 5, and elsewhere 6, slower and less dramatic benefits would be expected in COPD than in lung cancer after quitting smoking. Nevertheless, WHO data on COPD mortality in the Netherlands 4 also indicate that between 1990 and 2000 total male deaths have been stable, whereas death rates per 100,000 for the total adult population, and for males aged 75–79 yrs, have both declined by a similar proportionate amount.

While recognising that the primary purpose of the authors' model is to estimate total future costs due to chronic obstructive pulmonary disease, regardless of how these costs arise, the authors hardly comment on the extent to which their estimates depend on demographic changes, in particular, increased age of the population (which perhaps represents medical “success” but increases costs and worries pension funds) and how much depends on the persistence of smoking-related disease (which is amenable to preventive medicine). The increases presented for prevalence and mortality could potentially be explained entirely by population ageing, but there is no quantification of these two major factors to support or refute this possibility. Such information might help the medical reader to better understand the paradox that, while smoking is the most important aetiological factor for causing physician-diagnosed chronic obstructive pulmonary disease, its prevalence and mortality can be projected to continue to increase even after 45 yrs of reduction in cigarette smoking by Dutch males.