Inklusionskriterier

Inklusionskriterier, or inclusion criteria, are predefined characteristics that determine who may participate in a research study. They define the study population and ensure that participants share the conditions or attributes of interest. Inclusion criteria are specified before data collection in the study protocol or register and may include diagnosis or disease, age range, sex, comorbidity profile, disease severity, prior treatments, language proficiency, ability to provide informed consent, and setting (for example hospital or community). They should be objective and verifiable, using validated diagnostic criteria where possible.

Inclusion criteria are complemented by exclusion criteria, which identify factors that disqualify otherwise eligible individuals and help protect participant safety and limit confounding. Together, inclusion and exclusion criteria shape the study sample, influence recruitment feasibility, external validity, and statistical power. In systematic reviews or meta-analyses, inclusion criteria also specify the types of studies, populations, interventions, comparators, and outcomes (PICO).

Operational criteria should be clear and measurable to minimize subjective judgment during screening. They may allow pragmatic flexibility while maintaining core eligibility. Examples include: age 18–65; confirmed diagnosis of a condition by criteria Y; no contraindicated comorbidity; ability to complete questionnaires in language Z.

Ethical and practical considerations require that criteria be justified and documented, and updated only with sound rationale. Predefined criteria support transparency, reproducibility, and consistency across study screening and reporting.