Cohort Profile: the 'children of the 90s'--the index offspring of the Avon Longitudinal Study of Parents and Children

Abstract

The Avon Longitudinal Study of Parents and Children (ALSPAC) is a transgenerational prospective observational study investigating influences on health and development across the life course. It considers multiple genetic, epigenetic, biological, psychological, social and other environmental exposures in relation to a similarly diverse range of health, social and developmental outcomes. Recruitment sought to enroll pregnant women in the Bristol area of the UK during 1990-92; this was extended to include additional children eligible using the original enrollment definition up to the age of 18 years. The children from 14541 pregnancies were recruited in 1990-92, increasing to 15247 pregnancies by the age of 18 years. This cohort profile describes the index children of these pregnancies. Follow-up includes 59 questionnaires (4 weeks-18 years of age) and 9 clinical assessment visits (7-17 years of age). The resource comprises a wide range of phenotypic and environmental measures in addition to biological samples, genetic (DNA on 11343 children, genome-wide data on 8365 children, complete genome sequencing on 2000 children) and epigenetic (methylation sampling on 1000 children) information and linkage to health and administrative records. Data access is described in this article and is currently set up as a supported access resource. To date, over 700 peer-reviewed articles have been published using ALSPAC data.

Figure 1

The life course of the ALSPAC Study Logo

Figure 2

The ALSPAC Eligible Study Area; the study area within the UK and details illustrating the three eligible NHS District Health Authorities (DHAs). © Crown Copyright/database right 2011. An Ordnance Survey/EDINA supplied service

Figure 3

The ALSPAC enrolment campaign flow diagram

Figure 4

Response rates to mother/primary carer completed questionnaires about the child (assessments from 4 weeks old to 18 years of age)

Figure 5

Response rates to child study clinical assessments (excluding CiF sub-sample clinics) and self-completed questionnaires (assessments from 65 months to 18 years). ^aCCXB questionnaire was administered to a subsample of the cohort. ^bCCXC questionnaire piloted a new internet-based data collection and did not receive the normal reminder follow-up procedure

Figure 6

ALSPAC Study attrition^a flow diagram. ^aIndividuals excluded from follow-up due to a ‘permanent’ status change that remained in place up to the age of 18 years (e.g. individuals became untraceable and were not found again before the age of 18 years). Individuals for whom a change in status meant they were temporarily excluded from follow-up are not included and, therefore, this diagram under-represents attrition at individual data collection time points. ^bPost-18-year age tracing and recruitment initiatives in ALSPAC may result in some individuals being included in future follow-up

Figure 7

ALSPAC assessment response across multiple data collection time points. (a) Response to all 55* child-based questionnaires and ‘Focus’ clinical assessments across multiple time points. Number of questionnaires about the child (completed by the child or by the child’s mother/carer) or Focus clinical assessments completed by the child (excludes CiF sub-sample clinics and the puberty, CCXB and CCXC subsample questionnaire assessments). (b) Response to 25* CCQs across multiple time points. Number of questionnaires completed by the child (excludes the puberty, CCXB and CCXC subsample questionnaires). (c) Attendance at 9* child ‘Focus’ clinical assessment visits. Number of ‘Focus’ clinical assessments attended by the child (excludes the CiF sub-sample clinics)