LAUSR

The burden of chronic diseases in Europe will inevitably grow in the nearby future for the reasons outlined in the paper by Brennan et al. [1] in this issue. The life expectation is rapidly improving, but leaving an increasing proportion of those living longer with these diseases, and often with several diseases at the same time (multi-morbidity), either by co-incidence or because of some mutual synergistic relationships between them. In addition to the obvious suffering of the many older people, it puts huge logistic and economic challenges on the health care systems and hence to the societies in general. Moreover, there are already by now considerable disparities between and also within countries in the distributions of these health problems, which by themselves give rise to political tensions. When looking at these huge problems from a scientific point of view—in particular at how we as epidemiologists could help solving them—we may, as done by Brennan et al., emphasize the opportunities we have with continued exploration of the existing and forthcoming multiple large European cohort studies, further improved by closely coordinated integration and harmonization of the information available in the cohorts as aimed at in the European Cohort Consortium (ECC). This will surely generate a lot more of the type of results that the cohort study design as such is capable of, demonstrated by the long-lasting collaborative research of 521,000 participants in 10 countries within the framework of the European Prospective Investigation of Cancer (EPIC), and now emerging also from the utilization of the UK Biobank including another 500,000 participants. On the top of this, the coordination will likely also create opportunities to further increase the epidemiological quality of the evidence and thereby supporting translation of the results to trustworthy knowledge. Furthermore, such results may pave the way for or support the relevance of novel basic investigation in disease mechanisms, out of which may emerge new paths toward options for prevention and even treatment. So, there are no reasons to oppose the build of a consortium like ECC as long as it does not in any way limit the fundamental autonomy and implicit freedom of the researchers to pursue whatever they find as most interesting ideas in their own cohort data, alone or in collaborations with other cohorts, within or outside the ECC. The expected achievements by the ECC immediately invite considerations about how this sort of knowledge can be utilized to mitigate the huge and growing public health problems in Europe. If we take the pragmatic public health position of the receivers of this knowledge, we may start asking in which way the type of knowledge provided is or is not helpful, and, if helpful, what is needed to be able to use it for feasible actions in public health settings. A range of issues needs to be addressed to answer these questions, but two essential ones are about the adequacy of the cohort studies in addressing the public health problems and about the challenges in inferring what would happen if interventions were undertaken from the cohort studies like those included in the ECC that produce merely observational evidence. Before addressing the adequacy of the coverage of knowledge needed to address the public health problems, it is relevant to consider what has already been delivered of & Thorkild I. A. Sørensen [email protected]