TABLE 2—

Effect of Selected Exposures on the Incidence Rate of Hepatitis B Virus Infection Among Successfully Vaccinated Drug Users Over the 2-year Follow-Up, Long-Term Effectiveness of Accelerated Hepatitis B Vaccination Schedule

Predictor Variable	Total (No.)	No. With HBV Infection	Person-Years	Incidence Density	Adjusted Relative Risk (95% CI)a	P
Overall	707	10	1166	8.6	. . .
Vaccination schedule						.053
Standard	342	8	576	13.9	1.00 (Ref)
Accelerated	365	2	590	3.4	0.21 (0.04, 1.02)
Age, y						.422
< 40	250	3	394	7.6	1.00 (Ref)
≥ 40	457	7	772	9.1	0.53 (0.11, 2.5)
Gender						. . .
Male	543	8	881	9.1
Female	164	2	286	7.0
Race						.293
Non-African	59	1	130	7.7	1.00 (Ref)
African American	616	9	1036	8.7	3.5 (0.34, 36.27)
Education					. . .	. . .
≤ high school	534	9	885	10.2
> high school	173	1	281	3.6
HCV at enrollment	139	6	218	27.5	6.54 (1.49, 28.76)	.013
MSM	47	1	71	14.2	1.63 (0.19, 13.96)	.658
Past 30 d
IDU	36	0	52	0	. . .	. . .
Crack	656	9	1090	8.3		. . .
Cocaine	98	2	152	13.2		. . .
Methamphetamine	22	0	39	0		. . .
Fry	16	0	27	0		. . .
Marijuana	345	4	563	7.1		. . .
Alcohol	491	8	809	9.9		. . .
Heroin	19	0	28	0		. . .
Speedball	7	0	10	0		. . .
Ever used injecting drugs	146	4	233	17.2	1.75 (0.38, 7.95)	.47
No. drug use						. . .
< 2	138	0	224	0
≥ 2	569	10	942	10.6
Anti-HBs antibody (mIU/ml)b						.176
< 10	368	7	552.5	12.7	1.00 (Ref)
≥ 10	339	3	613.5	4.9	0.39 (0.1, 1.53)

Note. CI = confidence interval; HBs = hepatitis B; IDU = injecting drug use; MSM = men who have sex with men.

^aCox proportional hazard regression.

^bAt 12 months postenrollment.