Background: Participation rates in large cohort studies have decreased during the last 2
decades. The consequences of this trend for relative risk estimation are unknown. Methods …

Self-selection into prospective cohort studies and loss to follow-up can cause biased
exposure-outcome association estimates. Previous investigations illustrated that such …

Loss to follow-up in cohort studies may result in biased association estimates. Of 61,895
women entering the Danish National Birth Cohort and completing the first data-collection …

Longitudinal cohort studies can provide important evidence about preventable causes of
disease, but the success relies heavily on the commitment of their participants, both at …

Background The aim of pregnancy cohorts was to understand causes and development of
health and disease throughout the life course. A major challenge in cohort studies is to avoid …

Selfselection in epidemiological studies may introduce selection bias and influence the
validity of study results. To evaluate potential bias due to selfselection in a large …

Background Participants in cohort studies are frequently selected from restricted source
populations. It has been recognised that such restriction may affect the study validity …

In population-based cohort studies, a sample, or even the entirety, of a defined population is
selected for longitudinal assessment of exposure-outcome relations. Because of their …

Background Low participation at recruitment to the Danish National Birth Cohort (DNBC) has
raised concern about non-participation bias. Objective To study the socioeconomic pattern …

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 …