Other potential confounders or effect modifiers because of their known correlations with smoking and/or SRO, measured at wave 1, were: demographic characteristics (age, gender, race/ethnicity, marital status, education, employment status, income, urban residence, geographic region) and lifetime measures of DSM-IV Axis I and Axis II disorders. The Axis I disorders were categorised into mood disorders (major depression, dysthymia, bipolar I and bipolar II), anxiety disorders (panic disorder, social phobia, specific phobia, generalised anxiety), alcohol use disorders (alcohol abuse or dependence) and other substance use disorders (drug abuse or dependence). A history of attention deficit hyperactivity disorder (ADHD), queried only at wave 2, was used among the wave 1 predictors, its lifetime quality presumed since the DSM-IV criteria for ADHD include the presence of ADHD symptoms before age 7. All 10 of the Axis II personality disorders measured in Alcohol Use Disorder and Associated Disabilities Interview Schedule (AUDADIS-IV) (shown in table 1), measured at wave 1, were included as well.
