exclusioncriteria

Exclusion criteria are predefined conditions or factors that disqualify individuals from participating in a study or from being included in a review or analysis. They are part of the broader set of eligibility criteria, which also includes inclusion criteria, and are established before recruitment or study selection to safeguard safety, data quality, and interpretability. Together they define the eligible population and the scope of the evidence to be gathered.

In clinical trials, exclusion criteria identify medical or behavioral factors that could pose safety risks, confound outcome assessment, or interfere with the study protocol. Common examples include severe comorbidity, pregnancy, concurrent participation in another trial, known allergies to study interventions, cognitive impairment, or language barriers limiting informed consent.

In systematic reviews and meta-analyses, exclusion criteria specify study characteristics that render evidence unsuitable for synthesis, such as non-randomized design, inappropriate populations, outcomes not reported, or poor methodological quality. Screening is conducted against these criteria after initial study identification.

Impact and considerations: Exclusion criteria influence generalizability and may introduce selection bias if overly restrictive or inconsistently applied. Criteria are typically defined in the study protocol, documented in consent or screening records, and reviewed by ethics committees. Transparent reporting of exclusions helps readers appraise applicability and risk of bias.