TABLE 2.

Negative Binomial Regression of VA Substance Abuse Services: Baseline to 9 Months (Exp(β))

Baseline	Model 1	Model 2	Model 3
Need indicators
Days in last 30 experienced alcohol problems	1.04*	1.02	1.05**
Days in last 30 experienced drug problems	1.01	1.00	0.99
Days in last 30 experienced psychological problems	1.01	1.01	0.98
Any chronic medical problems interfere with life	0.71	0.81	1.23
Controls
Age	0.99	0.98	1.00
Race (White)	0.84	0.96	1.55
Sex (male)	1.83	1.41	1.38
Service preference (0=not at all; 4=extremely important)
Importance of treatment for alcohol problems		1.23***	1.20**
Importance of treatment for drug problems		1.39***	0.98
Test of peer effect
Substance abuse service use 3 mo prebaseline			1.18***
Randomized to peer specialist			1.71*
Akaike Information Criterion (AIC)	764.86	751.02	755.34
Finite Sample Corrected AIC	766.10	752.95	757.98
Bayesian Information Criterion	787.49	779.30	789.84
N †	125	125	125

^†4 extreme outliers excluded (x>60).

^*P≤0.05.

^**P≤0.01.

^***P≤0.001.