3. Results
3.1. Drug use and consequences
Outcomes were analyzed based on number of alcohol use
days (TLFB), number of cannabis use days (TLFB), number
of alcohol abuse and dependence symptoms (ADI), number
of cannabis abuse and dependence symptoms (ADI), and
score on the drug use consequences scale (PCS).
3.2. Relative outcomes
A repeated-measures analysis of variance (Group × Time)
with intake PESQ score as a covariate indicated significant
Group × Time interactions on all of drug involvement
variables, range of F(2) = 3.2–28.6 (all ps b .05). The effect
sizes (eta squared) ranged from 0.02 to 0.17. The ordering of
group means for the 6-month outcome scores revealed two
trends. First, both intervention groups (BI-AP and BI-A)
revealed better outcomes compared with the CON group
(Student–Newman–Keuls [SNK] post hoc tests, p b .05) on
five outcome variables (alcohol use days, cannabis use days,
alcohol abuse symptoms, alcohol dependence symptoms,
and PCS). Second, the BI-AP showed significantly better
outcomes (p b .05) than the BI-A and CON groups on three
variables (cannabis use days, cannabis abuse symptoms, and
cannabis dependence symptoms). To summarize, at least one
of the target condition (BI-A or BI-AP) was associated with
better results than the CON group for each drug involvement
variable, and the BI-AP group emerged as the bestperforming
group (Table 2).