Table 4.

Backward stepwise logistic regression (LR) analysis of OPRD1 SNPs in cases and controls

Variables	AD vs Con			DD vs Con			CD vs Con			OD vs Con
	P	β	OR	P	β	OR	P	β	OR	P	β	OR
Genotype LR additive
Male	< 0.001	−1.78	0.17	< 0.001	1.74	5.73	< 0.001	1.95	7.00	0.009	0.89	2.43
Age	< 0.001	0.17	1.19	< 0.001	0.14	1.15	< 0.001	0.15	1.16	< 0.001	0.12	1.12
OPRD1^2^G	—	—	—	—	—	—	—	—	—	0.04	1.27	3.56
Genotype LR dominant
Male	< 0.001	1.81	6.12	< 0.001	1.76	5.79	< 0.001	1.96	7.13	0.009	0.88	2.40
Age	< 0.001	0.18	1.19	< 0.001	0.14	1.15	< 0.001	0.15	1.16	< 0.001	0.12	1.12
OPRD1^5^T	0.06	0.75	2.12	0.09	0.77	2.16	0.09	0.83	2.28	—	—	—
OPRD1^7^C	0.04	−0.83	0.44	0.08	−0.82	0.44	0.07	−0.88	0.41	—	—	—
Genotype LR recessive
Male	< 0.001	1.82	6.18	< 0.001	1.79	6.02	< 0.001	1.94	6.94	0.003	1.02	2.78
Age	< 0.001	0.18	1.19	< 0.001	0.14	1.15	< 0.001	0.15	1.16	< 0.001	0.12	1.13
OPRD1^2^G	—	—	—	0.05	2.03	7.63	—	—	—	—	—	—
OPRD1^4^G	0.07	−0.72	0.49	0.03	−1.70	0.18	0.04	−1.80	0.16	0.09	−1.22	0.29
OPRD1^9^G	—	—	—	0.02	2.12	8.32	0.03	2.17	8.79	—	—	—
Haplotype LR
Male	< 0.001	1.48	4.38	< 0.001	1.46	4.31	< 0.001	1.54	4.67	< 0.001	0.94	2.55
Age	< 0.001	0.16	1.17	< 0.001	0.13	1.13	< 0.001	0.13	1.14	< 0.001	0.11	1.12
OPRD1^GCAACT	0.03	1.86	6.43	0.01	2.32	10.18	—	—	—	< 0.001	3.92	50.57

Abbreviations: AD, cases with alcohol dependence; CD, cases with cocaine dependence; Con, normal controls; DD, cases with drug (cocaine and/or opioid) dependence; OD, cases with opioid dependence.

Note: Only the covariates that were retained in the final regression step are listed. Statistically significant P-values are in bold.