PECOS framework is used for prevention, etiology and risk factor reviews, where the aim is to determine whether exposure to a substance, behavior, or environmental factor is associated with an outcome.
Example question: Does long-term air pollution exposure increase cardiovascular disease risk in urban adults?
Criteria | Definitions | Inclusion example | Exclusion example |
Population | Group(s) of individuals, organizations, or entities that are the primary focus of the study | e.g. Adults living in urban areas with documented air pollution exposure | e.g. Populations in occupational high-exposure settings (e.g. factory workers) |
Exposure | Condition, lifestyle factor, risk factor, event, or experience the population has been exposed to | e.g. Long-term exposure to PM2.5 or NO2 exceeding WHO guidelines | e.g. Short-term or acute pollution events |
Comparison | Group or condition without the exposure, used as a reference to assess effects | e.g. Adults in areas with low ambient air pollution levels | e.g. Studies with no low-exposure reference group |
Outcomes | Result or effect associated with the exposure being measured | e.g. Incidence or mortality from cardiovascular disease | e.g. Self-reported chest symptoms without clinical diagnosis |
Study design | Research design used in the study | e.g. Prospective cohort study | e.g. Cross-sectional study with no temporal data |
Other | Any additional information that affects a study's eligibility for your review or is helpful to consider during screening | e.g. Studies reporting pollutant concentrations using standardized measures | e.g. Studies conducted before modern air quality monitoring (pre-1990) |