In the subsequent study, where the metabolic parameters were measured, we compared the incidence of metabolic syndrome in antipsychotic-treated Danish psychiatric outpatients with the incidence of metabolic syndrome in the general population. We report on a dramatically increased prevalence of the metabolic syndrome, based on the IDF criteria, in antipsychotic-treated Danish psychiatric patients group compared with the general population, i.e. 48.2% vs. 29.6%, respectively. Only a few European studies using the IDF defi nition have been conducted among psychiatric patients. In comparison, the prevalence of the metabolic syndrome in our study is higher. A Dutch study from 2009 reaches a prevalence of the metabolic syndrome of 38%, but only 76% were on antipsychotic drug treatment (24). The prevalence, based on the IDF criteria, in antipsychotic-treated patients in Belgium was 36% (25). The difference in prevalence between the study from Belgium and our study may be explained by differences in mean age: in our study, the mean age was 47 years, whereas the mean age in the Belgian study was 36.5 years. In addition, in the Belgian study from 2006, data collection began in November 2003, and the Dutch study collected data between January 2003 and April 2007. As the prevalence of the metabolic syndrome has been increasing in recent years worldwide, it is of great importance to compare studies from similar time spans