| Characteristic | N | % |
|---|
| Sex |
| Male | 51 | 96 |
| Female | 3 | 4 |
| Age |
| Median (IQR) | 28 | 25–32 |
| Race |
| Mixed ancestry | 3 | 6% |
| Black African | 34 | 63% |
| Indian ancestry | 3 | 6% |
| White | 14 | 26% |
| > 10 years drug use history | 30 | 56% |
| Criminal record | 28 | 53% |
| Frequency of heroin use (current) |
| Daily | 1 | 2% |
| 1–2 times per day | 4 | 7% |
| 3–4 times per day | 15 | 28% |
| > 4 times | 31 | 57% |
| Missing | 3 | 6% |
| Duration of pattern of use |
| 1–3 months | 1 | 2% |
| 3–6 months | 3 | 6% |
| > 6 months | 47 | 87% |
| Missing | 3 | 6% |
| Injected heroin in last year | 10 | 19% |
| Drugs detected on urine (baseline) |
| Opioids | 54 | 100% |
| Cannabis | 17 | 32% |
| Cocaine | 8 | 15% |
| Amphetamine | 1 | 2% |
| Methamphetamine | 6 | 11% |
| Benzodiazepines | 1 | 2% |
| HIV positive | 7 | 13% |
| ECG abnormalitiesa | 0 | 0% |
- aNo abnormalities suggestive of cardiac disease
