Silent dropouts in health surveys: are nonrespondent absent teenagers different from those who participate in school-based health surveys?

OBJECTIVE: To compare the health problems, needs and behavior of pupils absent from school with participants in the Swiss Multicenter Adolescent Survey on Health.
METHODS: The present pupils' group (N = 3324; adolescents between 15 and 20 years old, randomly selected from high schools and professional centers of French-speaking Switzerland) answered a self-administered anonymous questionnaire. The absent pupils group (N = 96) was questioned on the phone by means of a shorter but similar version of the questionnaire.
RESULTS: The proportion of respondents reporting skin problems, weight concerns, sleep difficulties, headaches, stomach aches, as well as vision or dental problems was higher in the present pupils sample (p < 0.01). The percentages of teenagers reporting the need for help were higher in the present pupils sample than in the absent group: nutrition (21.8 vs. 9.4, p < 0.01) stress (44.2 vs. 31.3, p < 0.05), depression (28.4 vs. 18.9, p < 0.05), sleep problems (21.3 vs. 12.1, p < 0.05), sports (9.2 vs. 4.2, p < 0.05), and love life (31.5 vs. 14.5, p < 0.01). The rates of hospitalizations and injuries were lower among absent pupils (28.2 vs. 40.1, p < 0.01). A higher proportion of absent students were sexually active (p < 0.05). They had a tendency to use tobacco, alcohol, and cannabis more frequently than did present pupils (p < 0.05).
CONCLUSION: Within the Swiss context, nonparticipation owing to school absenteeism is probably related less to physical or chronic health problems that to lifestyles which predispose these students to truancy.