Methods The cross-sectional survey will be conducted in 12 European countries (Bulgaria, England, France, Germany, Greece, Ireland, Italy, Latvia, Poland, Portugal, Romania, and Spain), representing geographical, legislative and cultural variations across the EU. In each of the 12 selected countries, approximately 1000 individuals, representative of the general population aged 15 years and over will be enrolled. The final sample will therefore include a total of approximately 12,000 subjects. The sample size in each specific country will allow us to obtain prevalence estimates with a maximum standard error (SE) lower than ± 1.6%. Therefore, with such a sample size we will be able to provide stable prevalence estimates (with a relatively small 95% confidence interval), overall, but also in each specific country.