Table 1:
Participants’ Demographics and Clinical Characteristics (mean ± S.E. or median & range)
| Non-Users (N=56) | Primarily-K (N=60) | K + PolyS (N=64) | p-value | |
|---|---|---|---|---|
| Age (years) | 23.9 ± 0.6 | 26.0 ± 0.6 | 25.6 ± 0.6 | 0.048 a |
| Age range | (18 – 41) | (19 – 39) | (18 – 41) | |
| # Men (%) | 24 (42.1%) | 37 (61.7%) | 36 (56.3%) | 0.092b |
| Education (years) | 13.6 ± 0.3 | 9.2 ± 0.3 | 9.6 ± 0.2 | <0.001 a |
| Monthly Income (*1000HKD) | 8.9 ± 1.2 | 5.3 ± 0.9 | 5.4 ± 1.5 | 0.063a |
| BDI total score (0–63) | 3.8 ± 0.6 | 12.5 ± 1.3 | 14.7 ± 1.3 | <0.001 a |
| HADSA (0–21) | 2.8 ± 0.3 | 5.3 ± 0.5 | 6.9 ± 0.5 | <0.001 a |
| SDS scale score (0–15) | - | 8.3 ± 0.4 | 8.5 ± 0.4 | 0.666c |
| Lifetime alcohol user, n (%) | 34 (60.7%) | 44 (73.3%) | 58 (92.1%) | 0.148b |
| Days of alcohol use in past month | 0.9 ± 1.4 | 3.1 ± 6.8 | 3.3 ± 7.0 | 0.914d |
| Completed MRI scans, n (%) | 46 (80.7%) | 39 (65.0%) | 41 (64.1%) | 0.090b |
| Ketamine usage pattern | ||||
| Age of first use | - | 17.0 ± 0.4 | 16.0 ± 0.4 | 0.05c |
| Age of regular use | - | 19.0 ± 0.6 | 18.4 ± 0.4 | 0.139c |
| Duration of regular use (months) | - | 76.3 ± 5.5 | 77.7 ± 5.4 | 0.855c |
| Days of use in past 2 years (median, range) | - | 512.4 (97–730) | 650 (92–730) | 0.286d |
| Daily dosage (gram) | - | 3.2 (0.3–28) | 3 (0.2–28) | 0.879e |
| Lifetime usage (Log, gram) | - | 3.6 ± 0.1 | 3.7 ± 0.1 | 0.621c |
| Days since last use (median, range) | 63.0 (0 – 666) | 30.0 (0 – 486) | 0.075e | |
| DSMIV-dependence in past year | - | 50 (84.7%) | 57 (90.5%) | 0.615b |
| Cocaine Co-Use | ||||
| Lifetime use, n (%) | - | 45 (76.3%) | 55 (84.6%) | 0.240b |
| Lifetime regular use, n (%) | - | 17 (29.3%) | 45 (69.2%) | <0.001 b |
| Duration of regular use (months) | - | 12 (1–48) | 33 (1.5–105) | 0.007 e |
| # user (past 2 year) | 18 (30.5%) | 41 (64.1%) | <0.001 b | |
| Days of use in past 2 year | 21 (1–51) | 258 (5–728) | <0.001 d | |
| Months since last use (median, range) | - | 28 (0.5–133) | 3.5 (0–145.2) | <0.001 d |
| Methamphetamine Co-Use | ||||
| Lifetime use, n (%) | - | 27 (45.8%) | 31 (47.7%) | 0.830b |
| Lifetime regular user, n (%) | - | 10 (16.9%) | 19 (29.7%) | 0.096b |
| Duration of regular use (months) | - | 16 (1–144) | 12 (1.5–108) | 0.808e |
| # user (past 2 year) | 6 (10.2%) | 14 (21.9%) | 0.079b | |
| Days of use in past 2 year | 31 (0–62) | 97 (1–254) | 0.772d | |
| Months since last use (median, range) | 39 (0.8 – 212) | 14.1 (0–107.6) | 0.047 d | |
| Marijuana Co-Use | ||||
| Lifetime use, n (%) | - | 37 (62.7%) | 44 (67.7%) | 0.561b |
| Lifetime regular use, n (%) | - | 6 (10.2%) | 18 (27.7%) | 0.014 b |
| Duration of regular use (months) | - | 96 (3–136) | 12 (2–196) | 0.663e |
| # user (past 2 year) | 8 (13.8%) | 9 (14.3%) | 0.938b | |
| Days of use in past 2 year | 0 (0–4) | 96 (5–526) | 0.002 d | |
| Months since last use (median, range) | 63 (0.23 −276.3) | 53 (0.03–200.3) | 0.375d | |
| Hallucinogens | ||||
| Lifetime use, n (%) | - | 35 (61.4%) | 35 (53.8%) | 0.400b |
| Lifetime regular use, n (%) | - | 18 (31.6%) | 18 (27.7%) | 0.639b |
| Duration of regular use (months) | - | 24 (3–120) | 18 (1–72) | 0.677e |
| # Any use in past 2 years, n (%) | - | 0 | 0 | - |
| Months since last use (median, range) | - | 77 (25–179) | 98.6 (26–236.9) | 0.197e |
a:
ANOVA;
b:
χ2;
c:
T test;
d
Kruskal-Wallis test;
e:
Mann-Whitney U;
p-values in bold indicates < 0.05. Primarily-K use: use ketamine >1/week in any 6 months in past 2 years; use other drugs less than 1/w in any 6 months in past 2 years. Days of use in past 2 years: calculated only among users, one missing value from cough medicine user; Duration of regular use: calculated only among users; Regular use: ≥1/week x 6 months. BDI = The 21-item version of Beck Depression Inventory. HADSA = Hospital Anxiety Depression Scale (Anxiety). SDS=Severity of Dependence Scale