Final multivariate model *describing association between Bacterial vaginosis and HIV infection with effect modification by Trichomoniasis, among 1367 FSWs recruited at 2 African and 2 Indian sites
| Variables | HIV prevalence by exposure level: ni/Ni (%) | Adjusted PR§ | 95% CI | p value |
| Bacterial vaginosis: | ||||
| Positive | 192/651 (29.49) | 1.25 | 1.05 to 1.48 | 0.01 |
| Negative | 177/716 (24.72) | 1.00 | – | – |
| Site: | ||||
| Mudhol/Jhamkandi | 23/49 (46.94) | 1.06 | 0.71 to 1.58 | 0.78 |
| Cotonou | 123/447 (27.52) | 0.63 | 0.50 to 0.79 | <0.0001 |
| Chennai | 56/355 (15.77) | 0.50 | 0.33 to 0.76 | 0.001 |
| Kampala (Ref.) | 167/516 (32.36) | 1.00 | – | – |
| Past history of STI: | ||||
| Yes | 198/615 (32.20) | 1.43 | 1.21 to 1.70 | <0.0001 |
| No | 171/752 (22.74) | 1.00 | – | – |
| Exerting an occupation besides commercial sex work: | ||||
| Yes | 243/906 (26.82) | 0.82 | 0.65 to 1.03 | 0.09 |
| No | 126/461 (27.33) | 1.00 | – | – |
| Current contraceptive method †: | ||||
| Hormonal | 65/221 (29.41) | 0.76 | 0.43 to 1.34 | 0.34 |
| IUD | 3/11 (27.27) | 0.99 | 0.35 to 2.82 | 0.98 |
| Female sterilisation | 43/294 (14.63) | 0.54 | 0.31 to 0.94 | 0.03 |
| Condom | 248/809 (30.66) | 0.89 | 0.53 to 1.50 | 0.67 |
| None (Ref.) | 10/31 (32.26) | 1.00 | – | – |
| Oral sex in the past 30 days: | ||||
| Yes | 5/30 (16.67) | 0.58 | 0.35 to 0.95 | 0.03 |
| No | 364/1337 (27.23) | 1.00 | – | – |
| Age (years): | ||||
| 15–19 (Ref.) | 10/66 (15.15) | 1.00 | – | – |
| 20–24 | 100/380 (26.32) | 1.85 | 1.03 to 3.34 | 0.04 |
| 25–29 | 109/357 (30.53) | 2.23 | 1.24 to 4.00 | 0.01 |
| 30–34 | 68/221 (30.77) | 2.70 | 1.50 to 4.88 | 0.001 |
| 35–60 | 82/343 (23.91) | 2.25 | 1.23 to 4.11 | 0.01 |
| Education duration (years) | ||||
| 0–6 | 240/782 (30.69) | 1.00 | – | – |
| 7–12 | 124/548 (22.63) | 0.76 | 0.63 to 0.92 | 0.005 |
| 13–17 | 5/37 (13.51) | 0.50 | 0.22 to 1.13 | 0.10 |
| Gonorrhoea‡: | ||||
| Positive | 52/111 (46.85) | 1.52 | 1.26 to 1.83 | <0.0001 |
| Negative | 316/1253 (25.22) | 1.00 | – | – |
| Candidiasis: | ||||
| Positive | 118/421 (28.03) | 1.20 | 0.99 to 1.45 | 0.06 |
| Negative | 251/946 (26.53) | 1.00 | – | – |
| Syphilis‡: | ||||
| Positive | 29/82 (35.37) | 1.26 | 0.96 to 1.67 | 0.09 |
| Negative | 339/1282 (26.44) | 1.00 | – | – |
| Trichomoniasis‡: | ||||
| Positive | 29/82 (35.37) | 1.20 | 0.82 to 1.74 | 0.34 |
| Negative | 339/1282 (26.44) | 1.00 | – | – |
| BV_TV¶ | – | 0.61 | 0.32 to 1.13 | 0.12 |
| 1.00 | – | – | ||
*This model includes, besides the site, all other covariables with p value <0.10 (though removal of neither resulted in a substantial change in the PR estimate during the confounders selection process), as well as TV and the product term between BV and TV.
† = 1 missing value.
‡ = 3 missing values.
§ PR=prevalence ratio.
¶ BV_TV=product term between Bacterial Vaginosis (BV) and Trichomoniasis (TV).