Syphilis incidence among injection drug users by self reported IDU risk behaviours in the past 6 months, Los Angeles County, 1994–6
| Injection risk behaviours | Cases/total sample | Cases/1000 person years | Rate ratio | 95% CI | p Value |
|---|---|---|---|---|---|
| *Total varies because of missing data. | |||||
| Overall incidence | 12/390 | 26.0 | — | 19.4, 32.3 | |
| Injected any drug: | |||||
| Yes | 11/343 | 27.3 | 1.5 | 0.84, 2.75 | >0.05 |
| No | 1/42 | 17.9 | 1.0 | ||
| Speedball injection: | |||||
| More than daily | 1/26 | 35.8 | 1.1 | 0.73, 1.92 | >0.05 |
| Daily or less | 2/113 | 15.4 | 0.5 | 0.27, 0.93 | <0.01 |
| Never | 9/246 | 30.2 | 1.0 | ||
| Cocaine injection: | |||||
| Daily or less | 3/52 | 52.5 | 2.3 | 1.42, 3.71 | <0.01 |
| Never | 9/331 | 22.8 | 1.0 | ||
| Heroin injection: | |||||
| More than daily | 8/187 | 39.2 | 2.9 | 1.60, 5.23 | <0.01 |
| Daily or less | 3/143 | 16.8 | 1.2 | 0.60, 2.54 | >0.05 |
| Never | 1/56 | 13.5 | 1.0 | ||
| Crack smoking: | |||||
| Sometimes | 9/200 | 39.1 | 3.0 | 1.66, 5.51 | <0.01 |
| Never | 3/190 | 12.9 | 1.0 | ||
| Backloaded syringe:* | |||||
| Sometimes | 4/72 | 47.2 | 2.1 | 1.33, 3.58 | <0.01 |
| Never | 7/273 | 21.6 | |||
| Recency of first injection: | |||||
| 5 years or less | 3/22 | 128.7 | 6.2 | 4.18, 9.42 | <0.01 |
| More than 5 years | 9/368 | 20.5 | |||
| Sites of shooting up: | |||||
| Transient | 3/81 | 32.5 | 1.3 | 0.78, 2.23 | >0.05 |
| Non-transient | 9/308 | 24.5 | |||
| Injected with other people: | |||||
| Always | 2/58 | 32.4 | 1.8 | 1.03, 3.26 | <0.05 |
| Sometimes | 8/240 | 28.2 | 1.6 | 0.88, 2.89 | >0.05 |
| Never | 2/89 | 17.6 | |||