Overall, 3- and 4-class models fit the data well; but in the latter, some class sizes were low, and for alcohol problems, a satisfactory 4-class solution could not be obtained (2 of the classes were highly similar). As solution comparisons across the 3 indicators were facilitated by a consistent number of classes, a 3-class solution was chosen for each indicator. The 4-class solutions for volume and heavy drinking are available from the authors upon request.
Alcohol Volume Model
In the 3-trajectory class solution (; Loglikelihood -2019.40, BIC 4219.78, AIC 4106.80, average class probabilities .874/.933/.942), Class 1 showed Low to Moderate use (16.5%); Class 2 showed High Desisting use (16.5% of sample); Class 3 showed High Chronic use (67%). The means for volume of use at age 29 years, weighted by estimated class probabilities for Classes 1, 2 and 3, were 1.177 (SD = 1.182), 0.265(SD = 0.473), and 2.435 (SD = 0.544), respectively —which yielded large effect sizes for Class 2 versus 1 (Cohen's d = -1.01), Class 3 versus 1 (d = 1.37), and Class 3 versus 2 (d = 4.26).
3-class solution for volume of alcohol use trajectories.
In Panel I of are the mean levels of the predictors for the 3 classes and Panel II shows the odds ratios for the multivariate regression results. Contrary to hypothesis, parent alcohol use did not significantly distinguish the early adult trajectory classes, although the mean levels indicated that the High Chronic class showed the highest levels of parent alcohol use and the Low to Moderate class the lowest levels. For antisocial behavior, again contrary to hypothesis, the High Chronic class was lower than the other 2 classes. Regarding age at first drunkenness, there were no significant differences among the 3 classes, although the means were in the expected direction.
Heavy-Episodic Drinking Model
In the 3 trajectory group solution for HED (; Loglikelihood -2537.09, BIC 5217.91, AIC 5128.19, average class probabilities .933/.970/.981), Class 1 showed Moderate Desisting HED (18% of sample); Class 2 showed Moderate Increasing drinking (13%); Class 3 showed Low Desisting drinking (69%). The Moderate Desisting class reported drinking 5 or more drinks in a row on about 1.3 occasions on average in the past 2 weeks at ages 18–19 years but only on about 0.3 occasions by ages 28-29 years. The Moderate Increasing class was drinking at a similar level initially but had increased to about 2.6 occasions on average by ages 28–29 years. Note that because the most occasions that could be reported was “3 or more times,” a number of men could have been drinking heavily on more than 3 occasions on average. For HED, the means at age 29 years, weighted by estimated class probabilities for Classes 1, 2 and 3, were 0.289 (SD = 0.454), 2.609 (SD = 0.488), and 0.044 (SD = 0.205), respectively —which yielded large effect sizes for Class 2 versus 1 (Cohen's d = 4.92), Class 3 versus 2 (d = −6.86), and a medium effect size for Class 3 versus 1 (d = −0.70).
3-class solution for heavy-episodic drinking trajectories.
Mean levels of the predictors for the 3-class HED model are shown in Panel I of , and the odds ratios for the multivariate regression results are shown in Panel II of . Mean levels indicated that the Moderate Increasing class showed the highest level of parent alcohol use, and the Moderate Desisting class showed the highest level of antisocial behavior. However, contrary to hypothesis, neither parental alcohol use nor antisocial behavior significantly distinguished the 3 HED classes. Age at first drunkenness was significantly higher for the Low Desisting class than for either of the other 2 classes.
3-Class Heavy-Episodic Drinking Model
Alcohol Problems Model
In the linear model 3-class solution for alcohol problems (; Loglikelihood -1355.36, BIC 2881.06, AIC = 2774.72, average class probabilities .937/.925/.986), Class 1 was Low Desisting (23%), Class 2 was High Desisting (14%), and Class 3 was Moderate Chronic (63%). The means for alcohol problems at age 29 years, weighted by estimated class probabilities for Classes 1, 2 and 3, were 0.102 (SD = 0.214), 0.382 (SD = 0.476), and 0.924 (SD = 0.509), respectively — which yielded a medium-effect size for Class 2 versus 1 (Cohen's d = 0.76) and large-effect sizes for Class 3 versus 1 (d = 2.11) and Class 3 versus 2 (d = 1.10).
3-class solution for alcohol problems trajectories.
Mean levels of the predictors for the 3 groups are shown in Panel I of . The mean levels were in the direction of high childhood and adolescent risk for the High Desisting class. In the multivariate prediction model, parent alcohol use, childhood antisocial behavior, and age at first drunken experience (Panel II of ) all significantly distinguished the alcohol problems classes (at the p < .10 level at least). The High Desisting class showed higher levels and the Moderate Chronic class marginally higher levels of parental alcohol use than did the Low Desisting class. The High Desisting class showed marginally higher levels of antisocial behavior than did the Moderate Chronic class. A higher age at first drunken experience was associated with membership in the Low Desisting class compared with either of the other 2 classes.
3-Class Alcohol Problems Model
Alcohol Treatment by Latent Class Membership
χ2 tests were conducted on the association of class memberships with alcohol treatment from ages 18–19 to 31–32 years. For alcohol volume, the proportions reporting any treatment by class were 24% for the Low Moderate class, 41% for the High Desisting class, and 26% for the High Chronic class, which was not a significant difference (χ2  = 4.02, p = .134). For HED, the treatment proportions were 21% for the Low Desisting class, 41% for the Moderate Desisting class, and 42% for the Moderate Increasing class, which was significant at the .05 level (χ2  = 8.94, p = .011). Finally, for alcohol problems, the treatment proportions were 15% for the Low Desisting class, 45% for the High Desisting class, and 28% for the Moderate Chronic class, which was a significant difference at the .05 level (χ2  = 8.44, p = .015). These findings indicate higher levels of treatment among the HED and alcohol problems desisting groups.
Class Membership Comparisons for the 3 Alcohol Use Indicators
Class membership for each of the 3 alcohol use indicators was compared 2 at a time () because small cell sizes for a number of cells precluded a 3-way comparison. χ2 tests indicated that each of the 2-way comparisons was significant: volume by HED (χ2 (4) = 17.72, p < .01), volume by problems (χ2 (4) = 90.04, p < .001), and problems by HED (χ2 (4) = 33.37, p < .001). Men in the 2 higher HED classes were very unlikely to be in the Low to Moderate volume class and most likely to be in the High Chronic volume class. Many men in the Low Desisting HED class were in the High Chronic volume class (61%), indicating a pattern of drinking frequently and/or at a substantial volume while rarely or never engaging in HED.
Concordance across Classes by Indicator
For alcohol problems versus volume, 86% of the men in the Moderate Chronic problems class also were in the High Chronic volume class. Those with High Desisting problems were most likely to be in the High Desisting volume class.
Finally, for alcohol problems versus HED, men in the Low Desisting problems class were all in the Low Desisting HED class. Men in the High Desisting problems class were very likely to be in 1 of the 2 desisting HED classes. Finally, men in the Moderate Chronic problems class accounted for all but 1 of the men in the Moderate Increasing HED classes. Overall, comparisons across trajectory class membership for the 3 indicators of — alcohol use indicated moderate to high concordance.