Table 1.
Characteristics of patients on methadone treatment for opioid use disorder
| Characteristic | Total (N = 240) | Responders (n = 167) | Nonresponders (n = 73) | p value |
|---|---|---|---|---|
| Age in years; mean (SD) | 37.1 (10.4) | 37.1 (10.7) | 36.9 (9.6) | 0.868 |
| Male; n (%) | 144 (60.0) | 105 (62.9) | 39 (53.4) | 0.169 |
| Married/common law; n (%) | 93 (38.8) | 66 (39.5) | 27 (37.0) | 0.711 |
| Employed; n (%) | 72 (30.0) | 53 (31.7) | 19 (26.0) | 0.375 |
| Completed post-secondary education; n (%) | 81 (33.8) | 52 (31.1) | 29 (39.7) | 0.196 |
| Ethnicity | ||||
| European; n (%) | 203 (84.6) | 139 (83.2) | 64 (87.7) | 0.381 |
| Native North/South American; n (%) | 19 (7.9) | 14 (8.4) | 5 (6.8) | 0.686 |
| Asian; n (%) | 2 (0.8) | 2 (1.2) | 0 (0) | 0.348 |
| Persian; n (%) | 1 (0.4) | 1 (0.6) | 0 (0) | 0.508 |
| Age of initial opioid use in years; mean (SD) | 23.1 (9.2) | 22.3 (8.8) | 25.0 (9.8) | 0.037 |
| Current cigarette smokers; n (%) | 214 (89.2) | 145 (86.8) | 69 (94.5) | 0.210 |
| Number of cigarettes smoked/day; mean (SD) | 18.0 (10.1) | 18.6 (10.5) | 16.6 (9.2) | 0.158 |
| Psychiatric comorbidity, self-reported; n (%) | 116 (48.3) | 81 (48.5) | 35 (47.9) | 0.937 |
| Family psychiatric history; n (%) | 195 (81.3) | 133 (79.6) | 62 (84.9) | 0.334 |
| Alcohol use disorder; n (%) | 42 (17.5) | 29 (17.4) | 13 (17.8) | 0.934 |
| Methadone dose (mg); mean (SD) | 89.5 (60.8) | 97.5 (67.5) | 71.2 (35.9) | 0.002 |
| Duration of MMT (months); mean (SD) | 40.5 (42.6) | 44.2 (44.1) | 31.8 (37.8) | 0.042 |
| Total number of opioid urine screens; mean (SD) | 65.7 (23.7) | 64.9 (20.7) | 67.5 (29.6) | 0.278 |
| Opioid use (% positive urine screens); mean (SD) | 18.9 (24.1) | 5.4 (5.6) | 49.8 (21.4) | <0.001 |
| BDNF rs6265 genotype frequencies; n (%) | ||||
| G/G | 153 (63.8) | 110 (65.9) | 43 (58.9) | 0.302 |
| A/G | 81 (33.8) | 52 (31.1) | 29 (39.7) | 0.196 |
| A/A | 6 (2.5) | 5 (3.0) | 1 (1.4) | 0.458 |
| DRD2 rs1799978 genotype frequencies; n (%) | ||||
| A/A | 213 (88.8) | 150 (89.8) | 63 (86.3) | 0.427 |
| A/G | 27 (11.3) | 17 (10.2) | 10 (13.7) | 0.427 |
Frequency for DRD2 rs1799978 G/G genotype is 0 % in this sample; therefore, descriptive statistics are not available
BDNF brain-derived neurotrophic factor, DRD2 dopamine receptor D2, SD standard deviation, MMT methadone maintenance treatment