Koortuuringuid

Koortuuringuid are observational longitudinal research designs in epidemiology that follow a defined group of individuals over time to study the relationship between exposures and outcomes. They can be prospective, collecting data as events occur in the future, or retrospective, using existing records to reconstruct past exposure and outcome data. Some studies are ambidirectional, combining both approaches.

In a koortuuringu study a cohort is selected based on a shared characteristic or exposure status and is followed for a defined period. Baseline data on exposures (for example lifestyle factors, environmental exposures, or medical history) and potential confounders are collected, and outcomes (such as disease incidence, mortality, or recovery) are ascertained through medical records, registries, or direct assessment. The design allows estimation of incidence and assessment of temporal order, enabling calculation of measures such as relative risk, incidence rate ratio, or hazard ratio.

Koortuuringuid offer advantages such as establishing temporality, studying multiple outcomes and exposures, and reducing recall bias relative to case-control studies. They are, however, subject to limitations including confounding, selection bias, loss to follow-up, changes in exposure status over time, and often high cost and long duration. Generalizability depends on how representative the cohort is of the broader population.

Typical applications include identifying risk factors for chronic diseases, understanding prognosis, and evaluating long-term effects of exposures or interventions. Data sources comprise questionnaires, medical records, registries, and periodic physical assessments. Notable examples include classic long-running cohort studies such as those investigating cardiovascular risk factors, cancer incidence, and lifestyle effects on health. Ethical considerations include informed consent, privacy protection, and secure data handling.