Weighted percentages and SEs measured the distribution of the covariates (demographic characteristics and lifetime psychiatric variables) reported at wave 1 for the sample with low mood and for the complementary sample of persons with no low mood. χ2 Tests were used to assess differences between comparison groups, for example, the at-risk sample and the complementary sample of NESARC participants who did not report low mood. Unadjusted and adjusted ORs (OR and AOR) and 95% CIs were calculated from univariate logistic regressions and multivariate logistic regressions, respectively, to assess prediction of wave 2 SRO in the sample of persons reporting low mood. The incidence of SRO at wave 2 (since the wave 1 interview) by smoking status, prior SRO and all other covariates at wave 1 were also calculated. The opposite temporal relationship of prior SRO (reported in wave 1) on future current smoking (reported in wave 2) was tested using the identical covariates for assessing predictors of wave 2 SRO, following Granger.29 All models were estimated with the PROC SURVEYLOGISTIC function of SAS statistical software V.9.2, with the results verified through an internal statistical review at the US Census Bureau.
