Table 1.
Characteristics, Exposures, and Risk Behaviors and Association With Incident Hepatitis C Virus Infection in Young Injectors in the UFO Cohort Study, San Francisco, California, 2000–2013
| Baseline Characteristic | Total No. | Incident HCV, No. (%) | Incidence per Person-year(95% CI) | Rate Ratio (95% CI) | P Value |
|---|---|---|---|---|---|
| Overall | 554 | 169 (30.5) | 23.1 (19.9–26.8) | ||
| Age, y | |||||
| ≤22 | 236 | 84 (35.6) | 25.8 (20.8–32.0) | 1 | |
| >22 | 318 | 85 (26.7) | 20.9 (16.9–25.9) | .81 (.60–1.10) | .17 |
| Sex | |||||
| Male | 370 | 107 (28.9) | 21.2 (17.5–25.6) | 1 | |
| Female | 180 | 62 (34.4) | 27.8 (21.6–35.5) | 1.31 (.96–1.79) | .09 |
| Years injecting | |||||
| ≤3 | 288 | 88 (30.6) | 22.8 (18.5–28.1) | 1 | |
| >3 | 264 | 81 (30.7) | 23.4 (18.8–29.1) | 1.03 (.76–1.39) | .86 |
| History of drug treatment | |||||
| No | 196 | 54 (27.6) | 19.4 (14.9–25.3) | 1 | |
| Yes | 353 | 114 (32.3) | 25.5 (21.2–30.6) | 1.31 (.95–1.82) | .1 |
| Ceased injecting for ≥3 mo (any during follow-up) | |||||
| No | 411 | 135 (32.9) | 33.3 (28.1–39.4) | 1 | |
| Yes | 143 | 34 (23.8) | 10.4 (7.4–14.6) | .31 (.22–.46) | <.01 |
| Drug injected most days, last mo | |||||
| Speed/cocaine/crack | 188 | 49 (26.1) | 17.5 (13.2–23.1) | 1 | |
| Heroin/heroin mixed | 337 | 119 (35.3) | 29.6 (24.7–35.4) | 1.69 (1.21–2.36) | <.01 |
| Injection frequency, last mo | |||||
| Less than daily | 367 | 92 (25.1) | 17.5 (14.3–21.5) | 1 | |
| Daily | 187 | 77 (41.2) | 37.1 (30.0–46.3) | 2.11 (1.56–2.86) | <.01 |
| No. of injection events, last mo | |||||
| >100 | 129 | 51 (39.5) | 37.3 (28.4–49.1) | 1 | |
| 30–100 | 198 | 72 (36.7) | 30.6 (24.3–38.5) | .82 (.57–1.18) | .27 |
| <30 | 226 | 46 (20.4) | 12.9 (9.7–17.2) | .35 (.23–.52) | <.01 |
| Borrowed used needle, last 3 mo | |||||
| No | 342 | 90 (26.3) | 18.0 (14.6–22.1) | 1 | |
| Yes | 209 | 79 (37.8) | 34.7 (27.8–43.3) | 1.93 (1.43–2.62) | <.01 |
| No. of people borrowed used needle from, last 3 mo | |||||
| 0 | 341 | 90 (26.4) | 18.0 (14.6–22.1) | 1 | <.01 |
| 1 | 113 | 39 (34.5) | 31.4 (22.9–42.9) | 1.75 (1.20–2.55) | <.01 |
| ≥2 | 91 | 37 (40.7) | 38.2 (27.7–52.7) | 2.13 (1.45–3.13) | |
| Used a contaminated cooker, last 3 mo | |||||
| No | 364 | 96 (26.4) | 18.4 (15.1–22.5) | 1 | |
| Yes | 188 | 73 (38.8) | 35.6 (28.3–44.8) | 1.94 (1.43–2.63) | <.01 |
| Injected someone's rinse, last 3 mo | |||||
| No | 350 | 90 (25.7) | 18.6 (15.1–22.8) | 1 | |
| Yes | 202 | 79 (39.1) | 32.2 (25.8–40.1) | 1.74 (1.28–2.35) | <.01 |
| Days drank alcohol, last mo | |||||
| 0 | 117 | 36 (30.8) | 23.5 (17.0–32.6) | 1 | |
| 1–14 | 230 | 70 (30.4) | 26.1 (20.7–33.0) | 1.11 (.74–1.66) | .61 |
| ≥15 | 207 | 63 (30.4) | 20.3 (15.8–25.9) | .86 (.57–1.30) | .47 |
| Any sex partner, last 3 mo | |||||
| No | 92 | 27 (29.4) | 19.7 (13.5–28.8) | 1 | |
| Yes | 462 | 142 (30.7) | 23.9 (20.2–28.1) | 1.21 (.80–1.82) | .37 |
| IDU sex partner, last 3 mo | |||||
| No | 257 | 71 (27.6) | 20.7 (16.4–26.2) | 1 | |
| Yes | 297 | 98 (33.0) | 25.2 (20.6–30.7) | 1.21 (.89–1.65) | .21 |
Abbreviations: CI, confidence interval; HCV, hepatitis C virus; IDU, injection drug user.