Studies on natural recovery from alcohol dependence: Sample selection bias by media solicitation?

Aims. To assess the selection bias of recruiting participants in studies on natural recovery from alcohol dependence through media solicitation. Design. Two samples with different recruitment strategies are compared. Setting. Media solicitation and general population. Participants. Sample 1 consists of 176 alcohol-dependent individuals remitted without formal help and recruited through media solicitation, sample 2 consists of 32 natural remitters derived from a representative general population study with a sample size of 4075 respondents and a response rate of 70.2%. Measurements. Several triggering mechanisms and maintenance factors of remission were assessed in a personal interview using standardized questionnaires. Findings. Results of logistic regression analyses show that media-solicited subjects were more often abstinent in the last 12 months, were more severely dependent, were less satisfied with eight life domains prior to remission and showed higher scores in a coping behaviour measure. Besides these major differences from the multivariate analysis, media subjects revealed more health problems prior to remission, experienced more social pressure to change drinking behaviour, and showed differences in reasons for not seeking help. Conclusions. Media solicitation leads to a sample selection bias in research on natural recovery from alcohol dependence. When measures to foster self-change are derived from such studies, findings from representative samples have to be considered.