Association between methadone dose and concomitant cocaine use in methadone maintenance treatment: a register-based study

Table 1 Sociodemographic characteristics ^a

Variables	Low dose group (LDG) (n = 200)	Medium dose group (MDG) (n = 273)	High dose group (HDG) (n = 140)	Total sample (N = 613)	p value
Gender, n (%) male	132 (66.0)	188 (68.9)	96 (68.6)	416 (67.9)	p > 0.05
Age, mean (SD), y	39.4 (±6.9)	38.4 (±6.4)	38.9 (±6.4)	38.9 (±6.6)	p > 0.05
Nationality, n (%) Swiss	169 (86.2)	230 (86.5)	118 (84.9)	517 (86.0)	p > 0.05
Marital status, n (%) Married	24 (12.0)	28 (10.3)	12 (8.6)	64 (10.4)	p > 0.05
Education, mean (SD), y	10.9 (±1.5)	10.9 (±1.6)	10.6 (±1.6)	10.8 (±1.6)	p > 0.05
Employed, n (%)^b	54 (29.0)	49 (18.8)	17 (12.6)	120 (20.6)	p < 0.001
Age at first heroin use, mean (SD), y^c	20.8 (±5.3)	19.2 (±4.3)	18.1 (±4.1)	19.5 (±4.7)	p < 0.01
Age at first cocaine use, mean (SD), y^d	22.3 (±6.9)	21.3 (±5.7)	19.7 (±4.3)	21.3 (±5.9)	p > 0.05

^aThe groups did not differ in any variable at the p < 0.05 level, except as noted.
^bSignificant difference between patients in the LDG, MDG and HDG (Kruskal-Wallis-Test; χ² = 15.587; df = 2; p < 0.001). The Mann Whitney test revealed that patients in the LDG were significantly more often employed than patients in the MDG (Z = − 2.878; p < 0.01) or in the HDG (Z = −3.603; p < 0.001).
^cSignificant difference between patients in the LDG, MDG and HDG for age at first heroin use (ANOVA; F_(2,277) = 6.206; p < 0.01). Post-hoc tests (Duncan Scheffé’s) revealed that patients in the LDG started heroin use significantly later in their lives than patients in the MDG (p < 0.05) or in the HDG (p < 0.01).
^dNo difference between the LDG, MDG and HDG for age at first cocaine use, but a trend for patients in the HDG to start cocaine use earlier in their lives (trend, p = 0.054).

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