There were two significant two-way interactions with Class 6 as the reference class. The age-by-baseline drinking interaction significantly predicted membership in Class 3 “mixed heavy and low risk drinking”, as compared to Class 6. Simple slopes analysis at one standard deviation below and above the average age indicated that baseline drinking did not predict membership in Class 3 “mixed heavy and low risk drinking” among younger individuals (OR=1.01, 95% CI: 0.92, 1.11), but greater baseline drinking significantly predicted a lower probability of membership in Class 3 among older individuals (OR=0.88, 95% CI: 0.80, 0.96). There was also a significant interaction between age and negative mood in predicting membership in Class 4 “heavy drinking-to-abstinence.” Greater negative mood symptoms predicted a greater likelihood of membership in Class 4 among older individuals (OR=2.54, 95% CI: 1.60, 4.05) but did not predict class membership among younger individuals (OR=1.30, 95% CI: 0.85, 1.99).
