查看文章

Background:

Although cohort members tend to be healthy and affluent compared with the whole population, some studies indicate this does not bias certain exposure-outcome associations. It is less clear whether this holds when socioeconomic position (SEP) is the exposure of interest.

Methods:

As an illustrative example, we use data from the Avon Longitudinal Study of Parents and Children. We calculate estimates of maternal education inequalities in outcomes for which data are available on almost the whole cohort (birth weight and length, breastfeeding, preterm birth, maternal obesity, smoking during pregnancy, educational attainment). These are calculated for the full cohort (n~ 12,000) and in restricted subsamples defined by continued participation at age 10 years (n∼ 7,000) and age 15 years (n∼ 5,000).

Results:

Loss to follow-up was related both to SEP and outcomes. For each outcome, loss to follow-up was …