Table 1. Demographic and Participant Characteristics of the Three Study Groups.
| Characteristic (Statistic) | Group |
p | ||
|---|---|---|---|---|
| Standard Treatment (n=37) |
Medication Contingency * (n=42) |
Voucher Incentive (n=41) |
||
| Demographics | ||||
| White (%) | 97.3 | 97.6 | 97.6 | 0.99 |
| Male (%) | 64.9 | 47.6 | 61.0 | 0.26 |
| Never married (%) | 48.6 | 52.4 | 58.5 | 0.67 |
| High school education (%) | 78.4 | 83.3 | 80.5 | 0.85 |
| Employed full-time (%) | 62.2 | 33.3 | 53.7 | 0.03 |
| Age (Yrs) M ± SD | 33.5 ± 11.1 | 31.6 ± 10.1 | 30.6 ± 9.1 | 0.44 |
| Monthly income ($) Md (Q1,Q3) | 1200 (700, 1933) | 1010 (600, 2100) | 1200 (490, 3200) | 0.92 |
| Opioid Use | ||||
| Prior treatment (%) | 67.6 | 71.4 | 80.5 | 0.41 |
| Regular use (Yrs) M ± SD | 7.0 ± 6.9 | 6.1 ± 5.7 | 5.6 ± 6.1 | 0.59 |
| Age of first use (Yrs) M ± SD | 22.5 ± 8.3 | 22.6 ± 7.7 | 21.5 ± 7.7 | 0.80 |
| Previous month’s spending on opioids ($) Md (Q1,Q3) |
1000 (300, 3000) | 1000 (400, 2250) | 1800 (500, 3000) | 0.61 |
| Preferred Route:** | ||||
| Intravenous (%) | 32.4 | 38.1 | 39.0 | |
| Intranasal (%) | 35.1 | 35.7 | 39.0 | |
| Oral (%) | 32.4 | 26.2 | 22.0 | 0.88 |
| Other Drug Dependence | ||||
| Alcohol (%) | 10.8 | 2.4 | 14.6 | 0.14 |
| Cocaine (%) | 18.9 | 11.9 | 24.4 | 0.34 |
| Sedative (%) | 8.1 | 7.1 | 14.6 | 0.47 |
| Cannabis (%) | 43.2 | 33.3 | 39.0 | 0.66 |
| Duration-cocaine use (Yrs) Md (Q1,Q3) |
1 (0, 5) | 1 (0, 3) | 1 (0, 5) | 0.50 |
| ASI Composite Scales | ||||
| Medical Md (Q1,Q3) | 0.08 (0, 0.49) | 0.08 (0, 0.51) | 0.00 (0, 0.34) | 0.42 |
| Employment Md (Q1,Q3) | 0.50 (0.31, 0.62) | 0.50 (0.29, 0.69) | 0.50 (0.18, 0.52) | 0.34 |
| Alcohol Md (Q1,Q3) | 0.00 (0, 0.06) | 0.00 (0, 0.04) | 0.00 (0, 0.08) | >0.99 |
| Drug Md (Q1,Q3) | 0.31 (0.18, 0.41) | 0.30 (0.20, 0.36) | 0.32 (0.20, 0.37) | 0.85 |
| Psychiatric Md (Q1,Q3) | 0.32 (0.05, 0.50) | 0.29 (0.09, 0.50) | 0.27 (0.09, 0.38) | 0.81 |
| Legal Md (Q1,Q3) | 0.19 (0, 0.35) | 0.13 (0, 0.40) | 0.20 (0, 0.31) | 0.92 |
| Family-Social Md (Q1,Q3) | 0.19 (0, 0.40) | 0.14 (0.02, 0.35) | 0.11 (0, 0.33) | 0.53 |
| Cocaine Md (Q1,Q3) | 0.00 (0, 0.01) | 0.00 (0, 0.01) | 0.00 (0, 0.03) | 0.97 |
| Opioids Md (Q1,Q3) | 0.70 (0.61, 0.73) | 0.65 (0.55, 0.72) | 0.70 (0.63, 0.74) | 0.02 |
| Buprenorphine dose Md (Q1,Q3) *** |
12 (12, 18) | 12 (12, 18) | 12 (12, 18) | >0.99 |
| 6 mg/day group (%) | 10.8 | 9.5 | 2.4 | |
| 12 mg/day group (%) | 54.1 | 50.0 | 58.5 | |
| 18 mg/day group (%) | 35.1 | 40.5 | 39.0 | 0.63 |
*
One subject in the medication contingency group provided no data; hence, the medication contingency group had n for denominator of 41.
**
No differences in the proportions of participants’ preferred routes of administration among the three experimental groups (χ2[df=4] =1.169, p=0.883).
***
No differences in the proportions of participants assigned to the three buprenorphine dose groups among the three experimental groups (χ2[df=4] =2.604, p=0.626).
M: mean; Md: median; SD: standard deviation; Q1,Q3: Inter-quartile range; Yrs: years; ASI: Addiction Severity Index.