[Facilitators of participation and implementation of the immigrant families' PELFI Sub-Cohort]

PELFI is a multicentre cohort study of migrant families in Spain. The objectives of this manuscript were: 1) to describe the recruitment strategies, data collection and the main socio-demographic characteristics according to geographical origin and sex of participants of the families; and 2) to assess the recruitment and data collection strategies that facilitated participation in the basal assessment of the Badalona and Santa Coloma de Gramanet cohort.

Descriptive study on a convenience sample of migrant and native families residing in Badalona and Santa Coloma de Gramanet. Health interviews were conducted on fathers, mothers and children>16 years; and medical examinations were performed.

There were 115 participating families. Within the recruitment strategies, snow ball achieved 69% cooperation. The cooperation rate of the study was 57.5% and that of the clinical sub-sample was 66.6%. Cooperation rate of the Chinese families was 38.5% and Chinese children >16 years old were not recruited. Twenty-eight percent of the interviews were conducted at weekends or during the evening. Families had a mean of 12.2 years of residence. Seventy-one point two percent of the children >16 years had completed secondary studies. The migrants had lower social class than natives (p < 0.05) and the migrant women had lower levels of education (p < 0.05).

Interacting frequently with the community, using different recruitment strategies simultaneously, incorporating researchers from the same geographical origin as participants, minimising language barriers and offering flexibility in conducting data collection facilitated the participation of the migrant families. The Chinese families presented greater difficulties. The study findings will facilitate the implementation of future cohort studies with similar characteristics.