Table 2.
Model results of logistic regression including 2-way age by baseline characteristic interaction estimating the odds of relapse. Within each model, the effect of the baseline characteristic on relapse is estimated separately among young adults and among older adults.
| Overall Effecta of 2-way Age*Baseline Measure Interaction | Effect of baseline measure among young adults (≤25 years) | Effect of baseline measure among older adults (>25 years) | ||||||
|---|---|---|---|---|---|---|---|---|
| Baseline characteristic measure | F(df) | p-value | aORb | 95% CI | p-value | aORb | 95% CI | p-value |
| Demographics | ||||||||
| Gender (ref=Female) | F(1, 558)=0.29 | 0.592 | 1.24 | (0.54, 2.86) | 0.611 | 0.96 | (0.62, 1.48) | 0.855 |
| Substance Use | ||||||||
| Any current heroin use (ref=No) | F(1, 558)=0.54 | 0.461 | 2.78 | (0.80, 9.63) | 0.107 | 1.66 | (0.93, 2.97) | 0.084 |
| Any current intravenous use (ref=No) | F(1, 558)=0.09 | 0.765 | 0.91 | (0.34, 2.46) | 0.855 | 1.07 | (0.72, 1.60) | 0.730 |
| Cigarette smoker (ref=Non-smoker) | F(2, 552)=1.40 | 0.247 | ||||||
| Every day | 2.08 | (0.27, 15.92) | 0.478 | 0.64 | (0.36, 1.14) | 0.130 | ||
| Some days | 3.89 | (0.31, 48.10) | 0.290 | 0.41 | (0.17, 0.98) | 0.046 | ||
| Any current cocaine/crack use (ref=No) | F(1, 558)=0.07 | 0.786 | 0.96 | (0.41, 2.23) | 0.917 | 0.84 | (0.57, 1.24) | 0.381 |
| Any current cannabis use (ref=No) | F(1, 558)=0.17 | 0.683 | 1.06 | (0.43, 2.62) | 0.899 | 0.86 | (0.59, 1.27) | 0.455 |
| Past Treatment History | ||||||||
| Current treatment is first treatment in lifetime (ref=No) | F(1, 558)=0.11 | 0.740 | 1.13 | (0.48, 2.65) | 0.784 | 0.96 | (0.64, 1.44) | 0.848 |
| Past methadone or buprenorphine treatment successful (ref=No) | F(1, 558)=0.45 | 0.504 | 0.92 | (0.35, 2.41) | 0.870 | 1.32 | (0.88, 1.97) | 0.181 |
| Past naltrexone treatment successful | NA* | |||||||
| Opioid Withdrawal | ||||||||
| Subjective Opioid Withdrawal Scale (range: 0–64) | F(1, 558)=0.13 | 0.719 | 1.14 | (0.72, 1.80) | 0.584 | 1.04 | (0.85, 1.27) | 0.718 |
| Other Psychiatric Symptoms/Disorders | ||||||||
| Hamilton Depression scale (ref=None) | F(2, 555)=0.07 | 0.929 | ||||||
| Mild | 1.19 | (0.47, 3.00) | 0.713 | 1.03 | (0.66, 1.60) | 0.912 | ||
| Moderate/Severe | 1.34 | (0.31, 5.81) | 0.694 | 1.05 | (0.55, 1.99) | 0.890 | ||
| Anxiety-depression moderate or extreme (EuroQoL) (ref=None) | F(1, 558)=1.99 | 0.159 | 1.95 | (0.72, 5.29) | 0.191 | 0.90 | (0.60, 1.36) | 0.620 |
| Suicidal thoughts (ref=No) | F(1, 558)=0.37 | 0.546 | 0.61 | (0.13, 2.98) | 0.545 | 1.07 | (0.45, 2.53) | 0.879 |
| Social/Living Situation | ||||||||
| Current homelessness (ref=No) | F(1, 558)=0.32 | 0.575 | 1.25 | (0.44, 3.58) | 0.678 | 0.90 | (0.58, 1.40) | 0.642 |
| Any friends/family with heroin/other opioid problems (ref=No) | F(1, 553)=0.69 | 0.407 | 0.50 | (0.18, 1.39) | 0.185 | 0.80 | (0.54, 1.18) | 0.256 |
| Legal Issues | ||||||||
| Current probation/parole (ref=No) | F(1, 557)=0.01 | 0.933 | 1.68 | (0.59, 4.78) | 0.327 | 1.60 | (0.91, 2.82) | 0.103 |
|
Motivation for Participating/
Attitudes Regarding Medication |
||||||||
| Participating to avoid relapse | NA* | |||||||
| Participating because of family/friends (ref=Disagree) | F(2, 555)=1.56 | 0.212 | ||||||
| Agree | 3.34 | (0.70, 15.97) | 0.131 | 0.90 | (0.51, 1.59) | 0.722 | ||
| Neutral | 0.63 | (0.22, 1.81) | 0.394 | 0.90 | (0.56, 1.44) | 0.651 | ||
| Prefer to receive BUP-NX (ref=Disagree) | F(2, 555)=1.96 | 0.142 | ||||||
| Agree | 1.06 | (0.30, 3.66) | 0.932 | 1.27 | (0.76, 2.11) | 0.360 | ||
| Neutral | 0.37 | (0.11, 1.19) | 0.095 | 1.05 | (0.65, 1.69) | 0.833 | ||
| Prefer to receive XR-NTX (ref=Disagree) | F(2, 555)=0.56 | 0.573 | ||||||
| Agree | 1.24 | (0.38, 4.06) | 0.725 | 0.72 | (0.41, 1.24) | 0.231 | ||
| Neutral | 0.67 | (0.23, 1.93) | 0.459 | 0.67 | (0.41, 1.10) | 0.116 | ||
| Receiving a preferred medication (ref=No) | F(1, 557)=0.03 | 0.870 | 0.97 | (0.42, 2.26) | 0.944 | 0.90 | (0.59, 1.37) | 0.613 |
| Cognition | ||||||||
| Trails Difference (B-A) | F(1, 558)=0.09 | 0.763 | 1.01 | (0.66, 1.54) | 0.976 | 1.08 | (0.89, 1.31) | 0.432 |
| Stroop Color-Word raw scorec | F(1, 552)=0.05 | 0.825 | 1.01 | (0.62, 1.64) | 0.966 | 1.07 | (0.88, 1.30) | 0.484 |
| Stroop Interference raw scorec | F(1, 552)=0.07 | 0.792 | 1.04 | (0.64, 1.71) | 0.862 | 0.97 | (0.81, 1.18) | 0.780 |
*
NA indicates that model did not converge due to zero cells
a
Overall effect is a test of the type 3 overall effect of age by baseline measure adjusting for treatment, which tests whether the effect of the baseline measure on the odds of relapse significantly differs between young adults and older adults
b
aOR; adjusting for treatment assignment
c
Analyses using t-scores instead of raw scores for Stroop tests produced similar results