Table 3.
Univariate associations between general characteristics, drug use characteristics, sexual risk behaviour characteristics and HIV and HCV seroconversion among DU in the ACS.
| HIV | HCV | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Incidence (/100 PY) | sc | PY | IRR | 95% CI | P-value | Incidence (/100 PY) | sc | PY | IRR | 95% CI | P-value | |
| Harm reduction | ||||||||||||
| Level of harm reduction (definitions described in Table 1) | ||||||||||||
| No harm reduction | 3.80 | 18 | 473.6 | 1 | < 0.001 | 23.16 | 11 | 47.5 | 1 | < 0.001 | ||
| Incomplete harm reduction | 2.80 | 46 | 1640.8 | 0.74 | (0.43–1.27) | 24.12 | 34 | 141.0 | 1.04 | (0.53–2.05) | ||
| Full harm reduction | 1.22 | 18 | 1475.9 | 0.32 | (0.17–0.62) | 3.47 | 6 | 173.0 | 0.15 | (0.056–0.40) | ||
| Limited dependence | 0.13 | 1 | 758.1 | 0.035 | (0.005–0.26) | 0.57 | 1 | 174.9 | 0.024 | (0.003–0.19) | ||
| No dependence | 0.57 | 6 | 1048.4 | 0.15 | (0.060–0.38) | 1.64 | 5 | 305.2 | 0.071 | (0.025–0.20) | ||
| Methadone dosage | ||||||||||||
| 0 mg | 2.16 | 44 | 2036.9 | 1 | 0.084 | 8.34 | 34 | 407.7 | 1 | 0.21 | ||
| 0–60 mg | 1.37 | 21 | 1531.8 | 0.63 | (0.38–1.07) | 4.87 | 11 | 226.1 | 0.58 | (0.30–1.15) | ||
| ≥ 60 mg | 1.33 | 25 | 1880.6 | 0.62 | (0.38–1.01) | 5.67 | 12 | 211.8 | 0.68 | (0.35–1.31) | ||
| Needle exchange programme (% of needles obtained via) | ||||||||||||
| No recent injecting | 0.38 | 10 | 2633.8 | 1 | < 0.001 | 1.60 | 10 | 623.4 | 1 | < 0.001 | ||
| 0% | 3.07 | 26 | 847.3 | 8.08 | (3.90–16.8) | 19.66 | 18 | 91.6 | 12.3 | (5.66–26.6) | ||
| 1–99% | 2.30 | 8 | 347.8 | 6.05 | (2.39–15.4) | 30.56 | 11 | 36.0 | 19.0 | (8.09–44.9) | ||
| 100% | 2.91 | 46 | 1578.8 | 7.67 | (3.87–15.2) | 19.10 | 19 | 99.5 | 11.9 | (5.54–25.6) | ||
| Change in methadone dosage compared to previous visit | ||||||||||||
| No change | 1.34 | 39 | 2917.1 | 1 | 0.11 | 3.73 | 16 | 428.4 | 1 | < 0.001 | ||
| Increase | 1.82 | 18 | 991.5 | 1.36 | (0.78–2.37) | 3.64 | 5 | 137.2 | 0.98 | (0.36–2.66) | ||
| Decrease | 1.67 | 13 | 778.5 | 1.25 | (0.67–2.34) | 5.83 | 6 | 102.8 | 1.56 | (0.61–3.99) | ||
| Unknown | 2.56 | 20 | 781.2 | 1.99 | (1.12–3.83) | 16.51 | 31 | 187.8 | 4.42 | (2.42–8.08) | ||
| General characteristics | ||||||||||||
| Sex | ||||||||||||
| Male | 1.57 | 53 | 3384.1 | 1 | 0.62 | 5.65 | 32 | 566.0 | 1 | 0.085 | ||
| Female | 1.78 | 37 | 2084.3 | 1.13 | (0.74–1.72) | 8.96 | 26 | 290.2 | 1.58 | (0.94–2.66) | ||
| Age (per 10 years increase) | 0.52 | (0.39–0.69) | < 0.001 | 0.46 | (0.32–0.65) | < 0.001 | ||||||
| Homelessness | ||||||||||||
| No | 1.58 | 82 | 5176.5 | 1 | 0.18 | 6.5 | 52 | 799.6 | 1 | 0.29 | ||
| Yes | 2.74 | 8 | 291.9 | 1.71 | (0.83–3.54) | 10.6 | 6 | 56.7 | 1.63 | (0.70–3.79) | ||
| Hospitalization in preceding 6 months | ||||||||||||
| No | 1.56 | 80 | 5124.1 | 1.86 | (0.96–3.59) | 0.09 | 6.85 | 56 | 817.1 | 0.75 | (0.18–3.05) | 0.67 |
| Yes | 2.90 | 10 | 344.3 | 1 | 5.11 | 2 | 39.2 | 1 | ||||
| HCV/HIV status at visit | ||||||||||||
| Negative | 1.13 | 10 | 888.5 | 1 | 0.41 | 6.13 | 51 | 831.5 | 1 | 0.0055 | ||
| Positive | 1.73 | 79 | 4553.6 | 1.54 | (0.80–2.98) | 34.82 | 5 | 14.4 | 5.68 | (2.27–14.2) | ||
| Acute infection in previous 6 months | 4.64 | 1 | 21.6 | 4.12 | (0.53–32.2) | 19.18 | 2 | 10.4 | 3.12 | (0.76–12.8) | ||
| Drug use variables | ||||||||||||
| Injecting in past 6 months | ||||||||||||
| Yes | 2.83 | 80 | 2831.1 | 7.45 | (3.86–14.4) | < 0.001 | 20.74 | 48 | 231.5 | 12.9 | (6.54–25.6) | < 0.001 |
| No | 0.38 | 10 | 2633.8 | 1 | 1.60 | 10 | 623.4 | 1 | ||||
| Borrowing of needles | ||||||||||||
| No recent injecting | 0.38 | 10 | 2633.8 | 1 | < 0.001 | 1.60 | 10 | 623.4 | 1 | < 0.001 | ||
| Recent injecting, no borrowing | 2.71 | 54 | 1996.3 | 7.12 | (3.63–14.0) | 14.51 | 23 | 158.5 | 9.05 | (4.31–19.0) | ||
| Recent injecting, borrowing 1–9 times | 3.30 | 12 | 363.6 | 8.69 | (3.76–20.1) | 48.11 | 14 | 29.1 | 30.0 | (13.3–67.5) | ||
| Recent injecting, borrowing ≥ 10 times | 2.17 | 1 | 46.2 | 5.71 | (0.73–44.6) | 23.78 | 2 | 8.41 | 14.8 | (3.25–67.7) | ||
| Frequency of injecting drug use in previous 6 months | ||||||||||||
| No injecting drug use in previous 6 months | 0.38 | 10 | 2633.8 | 1 | < 0.001 | 1.60 | 10 | 623.4 | 1 | < 0.001 | ||
| ≥ 2 times/day | 3.66 | 32 | 874.6 | 9.63 | (4.74–19.6) | 34.72 | 17 | 49.0 | 21.6 | (9.91–47.3) | ||
| Once/day | 2.71 | 3 | 110.6 | 7.15 | (1.97–26.0) | 25.45 | 1 | 3.93 | 15.8 | (2.03–123.8) | ||
| ≥ 2 times/week | 3.05 | 29 | 949.6 | 8.04 | (3.92–16.5) | 28.83 | 19 | 65.9 | 18.0 | (8.36–38.7) | ||
| Once a week | 0.00 | 0 | 147.5 | 0 | 8.23 | 1 | 12.2 | 5.13 | (0.66–40.1) | |||
| ≥ 2 times/month | 2.15 | 5 | 232.1 | 5.67 | (1.94–16.6) | 8.13 | 3 | 36.9 | 5.07 | (1.40–18.4) | ||
| Once/month | 3.92 | 4 | 102.0 | 10.33 | (3.24–33.0) | 15.19 | 2 | 13.2 | 9.47 | (2.07–43.2) | ||
| Less frequent | 1.53 | 6 | 393.2 | 4.02 | (1.46–11.1) | 8.36 | 4 | 47.9 | 5.21 | (1.63–16.6) | ||
| Main drug injected in previous 6 months | ||||||||||||
| No injecting drug use in previous 6 months | 0.38 | 10 | 2633.8 | 1 | < 0.001 | 1.60 | 10 | 623.4 | 1 | < 0.001 | ||
| Heroin | 2.26 | 13 | 574.2 | 5.96 | (2.61–13.6) | 19.62 | 9 | 45.9 | 12.2 | (4.97–30.1) | ||
| Cocaine | 1.81 | 8 | 442.7 | 4.76 | (1.88–12.1) | 24.31 | 10 | 41.1 | 15.2 | (6.31–36.4) | ||
| Speedball | 3.41 | 48 | 1408.6 | 8.97 | (4.54–17.7) | 18.30 | 21 | 114.7 | 11.4 | (5.37–24.2) | ||
| Amphetamines | 1.87 | 4 | 213.9 | 4.92 | (1.54–15.7) | 7.45 | (1.63–34.0) | |||||
| Methadone | 3.02 | 4 | 132.6 | 7.95 | (2.49–25.3) | 21.3 | (5.87–77.5) | |||||
| Other | 4.94 | 3 | 60.8 | 13.0 | (3.58–47.2) | 26.92 | 8 | 29.7 | 44.5 | (12.2–161.6) | ||
| Time since start injection drug use (years) | 0.93 | (0.91–0.96) | < 0.001 | 0.80 | (0.74–0.86) | < 0.001 | ||||||
| Sexual risk behaviour | ||||||||||||
| Heterosexual risk behaviour in previous 6 months | ||||||||||||
| No | 1.59 | 52 | 3270.9 | 1 | 0.87 | 7.57 | 36 | 475.9 | 1 | 0.59 | ||
| Yes | 1.73 | 38 | 2192.5 | 1.09 | (0.72–1.66) | 5.79 | 22 | 380.0 | 0.77 | (0.45–1.30) | ||
| HIV status of steady partner | ||||||||||||
| No steady partner | 1.63 | 67 | 4122.5 | 1 | 0.0013 | 7.83 | 53 | 676.7 | 1 | 0.020 | ||
| HIV-positive | 6.90 | 10 | 145.0 | 4.24 | (2.18–8.25) | 10.71 | 2 | 18.7 | 1.37 | (0.33–5.61) | ||
| HIV-negative | 1.14 | 11 | 963.7 | 0.70 | (0.37–1.33) | 2.62 | 3 | 114.6 | 0.33 | (0.10–1.07) | ||
| Unknown HIV status | 0.98 | 2 | 203.8 | 0.60 | (0.15–2.46) | 0.00 | 0 | 34.0 | 0 | |||
Abbreviations: sc = seroconversion, PY = person years, IRR = incidence rate ratio, 95% CI = 95% confidence interval.