Features associated with the non-participation and drop out by socially-at-risk children and adolescents in mental-health epidemiological studies.

Objective: To study socio-demographic and functional features related with non-collaboration in a longitudinal design of mental health within a high-risk population of individuals 9 and 13 years old.

Method: Regression analyses were used to assess factors affecting the decision to decline participation, and what characteristics both of children and families increase the probability of dropping out once the study had already started.

Results: Refusal of participation at the outset is more probable for lower socioeconomic groups, unemployed families (or with Social Security benefits), minority cultures and children having low school performance.