Which means you dont need much
Environmental risk factors and comorbidities of primary biliary cholangitis in Korea: a case-control study
Who can say what the heart saw
The following covariates were included in the final models: age (1824 years, 2544 years, 4564 years, 65 + years), gender (male, female), race/ethnicity (non-Hispanic white, non-Hispanic black, non-Hispanic other, Hispanic), education background (less than college, some college, college graduate), poverty level (below poverty level, near poverty level, above poverty level), user subgroups (i.e., defined in Table 1), and years of smoking cigarettes fairly regularly (for respondents who have smoked fairly regularly)