Startkohorte

Startkohorte is a term used primarily in German-language research to denote the initial group of participants enrolled at the outset of a study or program. The word is formed from Start and Kohorte and serves as a descriptive label for the baseline cohort. In epidemiology and longitudinal research, the startkohorte represents the baseline population from which exposure status, covariates, and outcomes are later assessed. Defining a clear startkohorte is crucial for internal validity and for interpreting time-related effects; the composition of the startkohorte affects generalizability and susceptibility to selection biases if the group differs systematically from the target population.

In practice, the concept appears across fields such as clinical cohorts, public health surveillance, and program evaluation. Some studies distinguish the startkohorte from subsequent follow-up cohorts or analytic cohorts created after data cleaning or after applying eligibility criteria. It is common to report the size of the startkohorte, eligibility criteria, recruitment period, and baseline characteristics, along with the number and reasons for loss to follow-up.

Terminology varies; the same idea is often described as the baseline cohort, initial cohort, or recruited cohort. While the term is especially common in German-language texts, readers in other languages may encounter equivalent concepts under different labels.

Example: A study on cardiovascular risk begins with a startkohorte of 5,000 adults enrolled in 2010, with 4,200 retained at five-year follow-up.

See also: Kohortenstudie, baseline, cohort, follow-up.