Univariate and multivariate Cox regression models: factors associated with HIV seroconversion among men who have sex with men participating in the ITACA cohort with at least one follow-up visit (December 2008–December 2011)*
| HIV sc % (n/N) | p-y | HR (95% CI) | p Value | HRa (95% CI)† | p Value | |
|---|---|---|---|---|---|---|
| Sociodemographics | ||||||
| Age | ||||||
| ≤24 | 11/344 | 398.1 | Ref | Ref | ||
| 25+ | 55/1884 | 2496.2 | 0.76 (0.40 to 1.46) | 0.41 | 0.62 (0.30 to 1.29) | 0.20 |
| Origin | ||||||
| Spanish-born | 30/1460 | 1909.8 | Ref | Ref | ||
| Foreign-born | 36/769 | 984.8 | 2.37 (1.46 to 3.85) | <0.001 | 1.98 (1.19 to 3.31) | 0.01 |
| Education level | 0.03 | |||||
| Low | 8/123 | 152.2 | 2.80 (1.29 to 6.07) | – | – | |
| Middle | 26/820 | 1043 | 1.31 (0.78 to 2.19) | – | – | |
| High | 32/1284 | 1697.3 | Ref | |||
| Occupation (employed) | ||||||
| Yes | 45/1679 | 2230.8 | Ref | |||
| No‡ | 21/546 | 659.5 | 1.68 (1.00 to 2.82) | 0.05 | – | – |
| Sexual orientation (homosexual) | ||||||
| Yes | 61/2023 | 2663 | Ref | |||
| No | 5/187 | 209.5 | 1.16 (0.47 to 2.91) | 0.75 | ||
| HIV testing | ||||||
| Previous HIV test at baseline | 0.001 | 0.01 | ||||
| 0–1 | 8/525 | 648.4 | Ref | Ref | ||
| 2–5 | 22/975 | 1300.3 | 1.34 (0.60 to 3.01) | 1.16 (0.50 to 2.67) | ||
| >5 | 35/692 | 909.7 | 3.01 (1.40 to 6.50) | 2.64 (1.14 to 6.11) | ||
| Sexual behaviour | ||||||
| Condomless anal sex with the last steady male partner with the following HIV status | <0.001 | <0.001 | ||||
| HIV+ | 2/53 | 68.3 | 1.62 (0.40 to 6.67) | 2 (0.48 to 8.35) | ||
| Unknown | 12/95 | 114.1 | 5.85 (3.11 to 11.00) | 6.94 (3.56 to 13.51) | ||
| HIV−/other§ | 50/2065 | 2696.3 | Ref | Ref | ||
| Number of casual partner | <0.001 | 0.02 | ||||
| 0–1 | 13/636 | 791 | Ref | Ref | ||
| 2–5 | 18/747 | 964.6 | 1.12 (0.55 to 2.29) | 1.08 (0.50 to 2.33) | ||
| 6–10 | 7/368 | 497.4 | 0.82 (0.33 to 2.05) | 0.70 (0.26 to 1.87) | ||
| >10 | 27/350 | 472.2 | 3.33 (1.71 to 6.46) | 2.20 (1.02 to 4.72) | ||
| Condomless anal sex with casual partner | ||||||
| Yes | 29/506 | 655 | 2.72 (1.67 to 4.44) | <0.001 | 2.21 (1.27 to 3.84) | 0.01 |
| No¶ | 36/1703 | 2219.7 | Ref | Ref | ||
| Contact with casual partner by Internet | ||||||
| Yes | 43/1121 | 1490.7 | 1.76 (1.05 to 2.95) | 0.03 | – | – |
| No | 22/1088 | 1382.3 | Ref | |||
| Intensive drug use** | ||||||
| Yes | 9/129 | 181.3 | 2.50 (1.23 to 5.09) | 0.01 | – | – |
| No | 53/2070 | 2673.5 | Ref | |||
| Self-reported STI | ||||||
| Syphilis | ||||||
| Yes | 2/20 | 19 | 5.82 (1.42 to 23.85) | 0.01 | – | |
| No | 62/2192 | 2857.4 | Ref | |||
| Gonorrhoea | ||||||
| Yes | 7/44 | 60.1 | 5.85 (2.70 to 12.88) | <0.001 | 3.52 (1.45 to 8.53) | 0.01 |
| No | 57/2168 | 2816.2 | Ref | Ref | ||
| Anogenital warts | ||||||
| Yes | 2/39 | 52.8 | 1.86 (0.45 to 7.60) | 0.39 | ||
| No | 62/2173 | 2823.5 | Ref | |||
| Date of enrolment | ||||||
| Calendar years | <0.001 | <0.001 | ||||
| 2009†† | 40/1246 | 2055.5 | Ref | Ref | ||
| 2010 | 23/776 | 753.4 | 2.88 (1.56 to 5.31) | 3.27 (1.71 to 6.28) | ||
| 2011 | 3/207 | 85.7 | 7.99 (2.22 to 28.80) | 6.31 (1.68 to 23.69) | ||
*Nineteen participants were excluded from the analysis because the questionnaire at time of the seroconversion follow-up visit was not collected.
†Adjusted model by age.
‡Included student, pensioner, sexual worker, retired, other.
§Consistent use of condom, non-steady partner, not to have penetrated.
¶Consistent use of condom, non-casual partner, not to have penetrated.
**Intensive drug use was defined as the use of at least one drug always or almost always during or before sex over the last 6 months.
††It includes data from December 2008.
HIV sc, HIV seroconverters; STI, sexually transmitted infection.