Assessment of participation biases for a confidential non-anonymous adolescent study: A based population study

A prospective study often receives a low participation rate that may alter the results quality. This study assessed the participation bias for a confidential non-anonymous adolescent survey among 1559 middle-school adolescents from north-eastern France (mean age 13.5 ± 1.3). They completed an anonymous questionnaire gathering demographic/socioeconomic features as well as school, behavior and health-related difficulties, and adolescent's assent to participate with perceived parents' consent (APC) if they were contacted for a confidential non-anonymous survey at home. Such a survey received an APC of 60%. The logistic model including all socioeconomic factors and school, behavior and health-related difficulties showed that the adolescents with APC were less often male (adjusted odds ratio = 0.77, p = 0.014), non-European immigrant (0.48, p = 0.016), living with a single parent (0.72, p = 0.046), in manual-worker families (0.69, p = 0.007), had less often low parents' education (0.70, p = 0.002), body-mass-index measurement refusal (0.60, p = 0.010), no regular physical/sports activity (0.70, p = 0.035), poor social relationships (0.73, p = 0.046) and poor living environment (0.63, p = 0.007). The percentage of subjects with APC steadily decreased with the number of these criteria: from 74% for 0 criterion to 19% for 6-8 criteria. Because of these possible strong participation biases the construction of adolescent cohorts and the results interpretation should be made with prudence.