Allelic and genotypic associations of DRD2 Taq I A polymorphism with heroin dependence in Spanish subjects: a case control study

Table 1 Features of heroin-dependent patients^a

	All	Males	Females	Gender comparisons
	(n = 281)	(n = 207)	(n = 74)	t or χ²	P
Age (years)	36.4 ± 6.3	36.6 ± 6.2	35.8 ± 6.5	t = 0.92	0.36
Heroin use
Age of onset (years)	20.1 ± 5.3	20.0 ± 5.1	20.3 ± 5.8	t = -0.45	0.66
Route of administration (%)
Intravenous	70.4	73.5	62.5	χ² = 2.38	0.31
Smoked	10.8	9.5	14.3
Intranasal	18.7	17.0	23.2
Non-opioid substance use^b (%)
Alcohol	56.6	59.9	47.3	χ² = 3.53	0.06
Benzodiazepines	42.7	43.0	41.9	χ² = 0.03	0.87
Cannabis	81.5	85.0	71.6	χ² = 6.49	0.01
Cocaine	71.5	70.5	74.3	χ² = 0.39	0.54

^a Values are mean ± SD unless otherwise indicated
^b Non-opioid substance use is defined as a regular and/or maladaptative pattern of non-opioid substance use during a longlife cumulative period longer than a year

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