Table 2.

Using club drugs and alcohol abuse to predict drop-out (Cox regression analyses, n=401)

		Univariate		Adjusted for significant background variables^a
	Row %	HR(95%CI)	P-value	HR(95%CI)	P-value
Club drug abuse
Use of any of the club drugs in the last six months
No	19.8	1.00		1.00
Yes	32.4	1.86 (1.01, 3.42)	0.047	1.90 (1.01, 3.56)	0.047
Use of methamphetamine in the last six months
No	19.7	1.00		1.00
Yes	35.5	2.13 (1.13, 4.02)	0.019	2.26 (1.15, 4.43)	0.017
Use of Ma Gu in the last six months
No	20.6	1.00		1.00
Yes	37.5	2.11 (0.67, 6.68)	0.204	1.79 (0.55, 5.80)	0.334
Use of Triazolam Tablets in the last six months
No	20.9	1.00		1.00
Yes	25.0	1.26 (0.18, 9.06)	0.817	1.51 (0.21, 10.97)	0.684
Use of ketamine in the last six months
No	21.0	1.00		1.00
Yes	20.0	0.97 (0.14, 6.98)	0.977	0.91 (0.12, 6.78)	0.926
Use of ecstasy in the last six months
No	20.9	1.00		1.00
Yes	25.0	1.26 (0.18, 9.06)	0.817	1.63 (0.22, 12.23)	0.635
Alcohol abuse
Overdrinking
No	19.8	1.00		1.00
Yes	25.0	1.30 (0.80, 2.12)	0.290	1.17 (0.72, 1.92)	0.519
Drinking frequency
Never	21.9	1.00		1.00
At least once	19.9	0.89 (0.58, 1.37)	0.603	0.84 (0.54, 1.29)	0.421
Drinks on a typical day when drinking
1–2 drinks	17.3	1.00		1.00
≥3 drinks	24.2	1.50 (0.78, 2.88)	0.229	1.38 (0.71, 2.69)	0.335
Frequency of having 6 or more drinks on 1 occasion when drinking
Never	16.2	1.00		1.00
At least once	27.8	1.85 (0.96, 3.56)	0.067	1.94 (1.00, 3.78)	0.051

Cox regression models adjusting for potential confounders (current marital status and number of times of compulsory drug detoxification), which predicted drop-out significantly at end of the study in a multivariate model (stepwise). HR: hazards ratio; CI: confidence interval.