was conducted in order to compare the prevalence of
COPD (all criteria) stratified by sex, age, schooling and
smoking status. Chi-square tests for heterogeneity and
trend were calculated. The relationships between
smoking status and all criteria were also adjusted for
sex, age and schooling using a multivariable regression.
However, due to the fact that the results
were unchanged, data from this adjusted analysis are
not shown.