Objectives: To describe the characteristics of the children of parents who did not respond to a follow-up questionnaire in a cohort of very preterm infants (EPIPAGE study) and to explore the reasons why they did not complete the questionnaires.
Methods: The non-respondents (N = 176) were the parents who did not return the questionnaires at 1 and 2 years. Contacts were organised by telephone calls and at home visits.
Results: The families of the non-respondents presented more socioeconomic difficulties and their children were born more preterm than those followed up without difficulties. The efforts made to contact the non-respondents revealed that their families were often confronted with major adverse socioeconomic difficulties, had severe illnesses and psychological troubles. Half of the children of the non-respondents were finally examined at the 5-year assessment. They showed lower performances at the cognitive development test and a poorer health status than the children of the respondents.
Conclusion: When the follow-up does not include the initial population in its totality, the socioeconomic difficulties are underestimated and probably also the rate of sequelae associated with very preterm delivery.