Epidemiological issues in comorbidity: lessons learnt from a pan-European ISADORA project

Aims: This article sets out to identify the issues that are relevant to understanding the current approaches used to determine the extent of the problems as a result of co-existent substance misuse and mental health problems comorbidity 1 in Europe. It is a fundamental prerequisite that it is based on robust epidemiological processes. Method: This article will describe an attempt to identify current data available in 2002 on the prevalence of co-morbidity per 100,000 inhabitants in Poland (Warsaw), Denmark (Aarhus), Finland (Tampere), England & Wales (London and Cambridge), Scotland (Dundee) and France (Paris) as part of the ISADORA project. Results: This exercise highlights methodological challenges in the epidemiology of comorbidity such as setting, subjects, intervention used and context, conceptual, units of contents, time window and accuracy of resolution and assessment method used. Conclusion: These issues need to be resolved before representative information can be interpreted.