Table 3.
Positive and negative ketamine expectancies of the RDS-sample in Taipei Metropolitan Area (N = 1115), by illicit drug use experience
| Ketamine expectancies | Illicit drug-naïve (Group 1; N = 840) |
Exclusive ketamine use (Group 2; N = 30) |
Polydrug ketamine use (Group 3; N = 132) |
The other illicit drug use (Group 4; N = 113) |
Group comparison | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| %wt | 95% CI | %wt | 95% CI | %wt | 95% CI | %wt | 95% CI | P | Post-hocb | |
| P1 (stand up to others) | 11.2 | (7.9–14.8) | 22.5 | (7.7–44.0) | 25.5 | (16.0–39.9) | 12.0 | (4.6–21.2) | <.001 | 3 > 1, 4 |
| P2 (join in with others) | 46.0 | (40.7–51.5) | 63.7 | (38.9–83.4) | 76.1 | (66.6–86.1) | 41.6 | (26.8–53.3) | <.001 | 3 > 1, 4 |
| P3 (drive better) | 4.7 | (2.4–7.6) | 19.2 | (1.4–41.5) | 1.0 | (0.0–2.7) | 7.6 | (0.0–17.2) | <.001 | 2 > 1, 3; 4 > 3 |
| P4 (make parties more fun) | 35.5 | (30.9–40.6) | 64.5 | (37.8–83.6) | 72.7 | (64.5–84.0) | 51.8 | (38.0–65.0) | <.001 | 3 > 1, 4; 2, 4 > 1 |
| P5 (enjoy a holiday) | 20.7 | (16.7–25.2) | 31.9 | (7.7–54.2) | 27.9 | (19.1–40.9) | 26.3 | (13.1–37.5) | .074 | |
| P6 (make the world a better place) | 13.7 | (10.4–17.5) | 15.4 | (1.9–33.6) | 19.3 | (10.3–30.5) | 22.6 | (9.6–37.6) | .041 | |
| N1 (lose controls and have accidents) | 71.2 | (66.3–76.5) | 51.2 | (29.2–79.2) | 54.8 | (40.8–65.4) | 56.0 | (40.9–69.3) | <.001 | 1 > 3, 4 |
| N2 (make people less friendly) | 51.4 | (46.2–57.1) | 28.4 | (12.4–53.2) | 18.6 | (9.8–27.7) | 39.5 | (25.2–51.6) | <.001 | 1, 4 > 3 |
| N3 (have a go at kids who are using) | 69.5 | (64.2–75.3) | 58.6 | (34.9–82.0) | 74.4 | (63.0–84.4) | 61.3 | (43.8–73.5) | .099 | |
| N4 (don’t understand things when using) | 66.8 | (60.9–72.5) | 73.0 | (52.0–90.4) | 61.8 | (48.9–73.1) | 52.4 | (36.5–64.4) | .014 | 1 > 4 |
| N5 (break and destroy things when using) | 67.9 | (62.6–73.6) | 35.9 | (17.7–63.1) | 41.3 | (28.1–55.2) | 49.0 | (33.6–60.2) | <.001 | 1 > 2, 3, 4 |
| N6 (have trouble remembering) | 74.3 | (69.3–79.9) | 77.4 | (57.5–94.4) | 74.4 | (63.8–83.6) | 64.5 | (48.3–77.3) | .170 | |
| Summary of expectancies | ||||||||||
| Positive sum, mean (SD) | 1.4 | (1.5) | 2.1 | (1.6) | 2.3 | (1.5) | 1.7 | (1.6) | <.001 | 3 > 1 |
| Negative sum, mean (SD) | 4.2 | (2.2) | 3.5 | (2.2) | 3.1 | (1.7) | 3.6 | (2.3) | <.001 | 1 > 2, 3; 4 > 2 > 3 |
| High Positive (≥ 1)a, n (%) | 53.5 | (48.3–58.9) | 71.8 | (47.5–89.6) | 86.0 | (79.3–94.1) | 70.3 | (56.4–80.3) | <.001 | 3 > 1,4; 4 > 1 |
| High Negative (≥ 5)a, n (%) | 59.1 | (53.5–64.9) | 28.5 | (12.6–55.0) | 30.3 | (16.9–43.4) | 46.4 | (31.5–58.6) | <.001 | 1 > 2, 3, 4 |
| Combination of expectancies, n (%) | <.001 | |||||||||
| Low Positive-High Negative | 17.3 | (14.1–21.6) | 9.2 | (0.0–25.3) | 0.8 | (0.1–2.0) | 12.3 | (4.8–21.0) | ||
| Low Positive-Low Negative | 29.3 | (23.4–34.9) | 19.8 | (2.9–39.6) | 12.8 | (5.5–20.5) | 17.5 | (10.0–29.5) | ||
| High Positive-High Negative | 41.5 | (36.1–46.6) | 19.2 | (6.4–42.5) | 29.8 | (16.1–42.6) | 34.9 | (21.3–45.8) | ||
| High Positive-Low Negative | 11.9 | (8.9–15.4) | 51.8 | (22.3–72.4) | 56.6 | (44.4–71.3) | 35.3 | (20.9–51.1) | ||
aThe median of the illicit drug-naïve as the cut-off, with High Positive being ≥ the median (i.e., 1) and High Negative being ≥ the median (i.e., 5)
bTukey’s HSD test in ANOVA; a Tukey-type multiple comparison for proportions in a 2*4 cross-tabulation for categorical variables (Elliott and Reisch 2006)