Efforts to convert refusers are effective in reducing non-response bias. However, converted late respondents cannot be seen as proxies of non-respondents, and are at best only indicative of existing response bias due to persistent non-respondents.

The higher prevalence of BN we detected relative to other studies should prompt further monitoring for a possible increasing trend. The female v. male ratios, especially for bulimia and BED, are decreasing. Given that more than half of those affected have never consulted any professional about their problems with eating or weight, routine inquiries about eating and weight by clinicians, school teachers/psychologists, and family members may help those who are at risk, especially among men.

Abstract. Aim: To summarize published findings in peer-reviewed journals of the first two waves of the Swiss Cohort Study on Substance Use Risk Factors (C-SURF), a longitudinal study assessing risk and protective factors of 5,987 young men during the phase of emerging adulthood (20 years at baseline, followed-up 15 months later). Methods: Included were 33 studies published until November 2014 focusing on substance use. Results: Substance use in early adulthood is a prevalent and stable behavior. The 12-month prevalence of nonmedical use of prescription drugs (10.6 %) lies between that of cannabis (36.4 %) and other illicit drugs such as ecstasy (3.7 %) and cocaine (3.2 %). Although peer pressure in the form of misconduct is associated with increased substance use, other aspects such as peer involvement in social activities may have beneficial effects. Regular sport activities are associated with reduced substance use, with the exception of alcohol use. Young men are susceptible to structural conditions such as the price of alcohol beverages or the density of on-premise alcohol outlets. Particularly alcohol use in public settings such as bars, discos or in parks (compared with private settings such as the home) is associated with alcohol-related harm, including injuries or violence. Being a single parent versus nuclear family has no effect on alcohol use, but active parenting does. Besides parenting, religiousness is an important protective factor for both legal and illegal substance use. Merely informing young men about the risks of substance use may not be an effective preventive measure. At-risk users of licit and illicit substances are more health literate, e. g., for example, they seek out more information on the internet than non-at-risk-users or abstainers. Discussion: There are a number of risk and protective substance use factors, but their associations with substance use do not necessarily agree with those found outside Europe. In the United States, for example, heavy alcohol use in this age group commonly takes place in private settings, whereas in Switzerland it more often takes place in public settings. Other behaviors, such as the nonmedical use of prescription drugs, appear to be similar to those found overseas, which may show the need for targeted preventive actions. C-SURF findings point to the necessity of establishing European studies to identify factors for designing specific preventive actions.