Table 3.
Demographic and behavioral risk factors* among seronegative IDUs according to presence or absence of HCV-specific T-cell responses
| Characteristic | T-Cell (+) | T-Cell (-) | OR (95% CI)† | p† |
|---|---|---|---|---|
| N (%) | N (%) | |||
| Total | 12 (46) | 14 (54) | ||
| Age (years)§ | ||||
| 18-25 | 4 (33) | 8 (57) | 1.0 | 0.22 |
| 26-33 | 8 (67) | 6 (43) | 2.67 (0.54, 13.2) | |
| Duration of injection drug use | ||||
| 0-6 years | 6 (50) | 7 (50) | 1.0 | 1.00 |
| 7-18 years | 6 (50) | 7 (50) | 1.0 (0.16, 6.17) | |
| Frequency of injection (past 30 days)§ | ||||
| ≤ 15 times (less often than every other day) | 3 (33) | 6 (43) | 1.0 | 0.43 |
| > 15 times | 9 (53) | 8 (57) | 2.25 (0.42, 12.1) | |
| Ever injected cocaine (or crack)§ | ||||
| No | 2 (17) | 6 (43) | 1.0 | 0.22 |
| Yes | 10 (83) | 8 (57) | 3.75 (0.59, 23.9) | |
| # times used a syringe previously used by another IDU (past 6 months) | ||||
| None | 6 (50) | 6 (43) | 1.0 | 0.88 |
| 1-9 times | 2 (17) | 5 (36) | 0.4 (0.06, 2.93) | |
| 10 or more times | 4 (33) | 3 (21) | 1.33 (0.20, 8.71) | |
| # times divided drugs (to share them) with a used syringe (past 6 months)‡ | ||||
| Never | 6 (50) | 12 (86) | 1.0 | 0.01 |
| 1-3 times | 1 (8) | 2 (14) | 1.0 (0.01, 23.1) | |
| 4 or more times | 5 (42) | 0 (0) | ∞ (1.27, ∞) | |
| # people who had used syringes used to split drugs (past 6 months)‡ | ||||
| None | 6 (50) | 12 (86) | 1.0 | 0.04 |
| 1-3 people | 5 (42) | 2 (14) | 5.0 (0.56, 53.9) | |
| 4-9 people | 1 (8) | 0 | ∞ (0.04, ∞) | |
| # times used cooker after another IDU stuck a used needle in it (past 6 months)§ | ||||
| Never | 6 (50) | 10 (77) | 1.0 | 0.07 |
| 1-3 times | 1 (8) | 2 (15) | 1.2 (0.09, 16.2) | |
| 4 or more times | 5 (42) | 1 (8) | 10.0 (0.4, 250) | |
| Any injection in shooting gallery (past 6 months) | ||||
| No | 10 (83) | 12 (86) | 1.0 | 1.00 |
| Yes | 2 (17) | 2 (14) | 1.2 (0.14, 10.1) | |
| Most common location of injection (past 6 months)§ | ||||
| Home¶ | 4 (33) | 8 (57) | 0.35 (0.08, 1.89) | 0.43 |
| Other places | 8 (67) | 6 (43) | 1.0 | |
| Who gave first injection‡ | ||||
| Self | 1 (8) | 5 (38) | 1.0 | 0.01 |
| Someone < 30 years old | 7 (58) | 8 (62) | 4.38 (0.33, 236) | |
| Someone 30 years or older** | 4 (33) | 0 (0) | ∞ (1.02, ∞) | |
Each of the 11 factors in this table was significantly associated with an increased likelihood of having HCV antibody among the 270 IDUs who participated in the Swan Study.
Odds ratios and P values reflect the association between the characteristic and the presence or absence of HCV-specific T-cell responses (comparing the 12 seronegative IDUs with T-cell responses to the 14 without them).
Factors significantly associated with HCV-specific, interferon-γ T-cell responses
Factors with associations with HCV-specific, interferon-γ T-cell responses that were not significant but are of expected direction and magnitude.
Injections in the home allow more opportunity for the use of safer injection techniques.
IDUs > 30 years old are more likely to have HCV infection than those younger.
Abbreviations: HCV, hepatitis C virus; IDUs, injection drug users; OR, odds ratio; CI, confidence interval.