. Author manuscript; available in PMC: 2013 Mar 1.

Published in final edited form as: Addict Behav. 2011 Nov 4;37(3):269–272. doi: 10.1016/j.addbeh.2011.11.003

Table 1.

Latent Trajectory Class^a and Mean Heavy Drinking Days by Class Over Time

Drug	Class Name	N in class	% in class	Mean Heavy Drinking Days, by Interview
Drug	Class Name	N in class	% in class	Baseline	6-mo	12-mo	18-mo	24-mo	30-mo	36-mo
Powder Cocaine	Steady high	60	8.5	7.22	7.53	7.21	6.78	7.07	6.31	5.88
	Declining^b	118	16.6	7.79	6.32	6.27	5.37	4.26	4.71	4.78
	Steady moderate^b	145	20.4	8.59	5.70	6.23	6.40	4.96	5.36	5.22
	Fast low^b	387	54.5	5.55	3.76	3.97	3.57	4.19	3.71	3.97

Crack Cocaine	Steady high	119	16.7	8.16	6.87	8.76	7.17	7.60	7.55	6.91
	Declining^b	165	23.2	8.07	6.58	5.89	5.83	4.04	4.45	4.14
	Increasing	81	11.4	6.60	3.52	4.13	3.64	4.90	4.12	4.43
	Fast low^b	345	48.6	5.53	3.60	3.49	3.61	3.59	3.30	3.37

Meth.	High to moderate	58	8.2	4.86	3.63	2.52	4.35	5.22	3.21	3.57
	Moderate to low	148	20.8	5.82	4.51	4.38	4.48	4.54	4.91	4.05
	Fast low^b	504	71.0	7.15	5.36	5.88	5.04	4.66	4.60	4.95

Classification of individuals based on their most likely latent class membership.

Time trend in heaving drinking days P < 0.05, based on results from generalized linear models for each class with time entered as the only independent variable.