Risk factors for incident anal chlamydia in the Health In Men Study (for those who reported casual partners)
| Incidence (/100 person-years) | Univariate | Multivariate | |||
|---|---|---|---|---|---|
| HR (95% CI) | p Value | HR (95% CI) | p Value | ||
| NA, not applicable; UAI, unprotected anal intercourse. | |||||
| Only age and those risk variables that were significant multivariate predictors and those sexual behaviours, that could have led to exposure of the anorectum to infection (UAI, receptive fingering, fisting, rimming and use of dildos) are reported in this table. | |||||
| *Attained age at each interview. | |||||
| †p for trend. | |||||
| ‡p for homogeneity. | |||||
| §Could not be included in the model because of the collinearity with UAI according to position. | |||||
| Age* (years) | 0.437† | 0.925† | |||
| <25 | 6.97 | 1 | 1 | ||
| 25–34 | 6.89 | 1.02 (0.50 to 2.09) | 1.10 (0.52 to 2.34) | ||
| 35–44 | 5.00 | 0.75 (0.37 to 1.55) | 0.84 (0.39 to 1.82) | ||
| 45–54 | 5.15 | 0.79 (0.36 to 1.75) | 0.99 (0.43 to 2.30) | ||
| >54 | 6.82 | 1.02 (0.41 to 2.59) | 1.47 (0.56 to 3.86) | ||
| Chlamydia contact | 0.001‡ | 0.001‡ | |||
| No | 5.49 | 1 | 1 | ||
| Yes | 17.11 | 3.03 (1.67 to 5.51) | 2.70 (1.48 to 4.94) | ||
| Number of casual partners in the past 6 months | 0.001† | 0.019† | |||
| 1 | 2.19 | 1 | 1 | ||
| 2–5 | 3.40 | 1.56 (0.54 to 4.51) | 1 | ||
| 6–10 | 6.00 | 2.80 (0.98 to 8.00) | 1.48 (0.86 to 2.56) | ||
| 11–50 | 7.47 | 3.48 (1.26 to 9.59) | 1.55 (0.96 to 2.51) | ||
| >50 | 11.80 | 5.69 (1.95 to 16.59) | 2.12 (1.16 to 3.90) | ||
| Unprotected anal intercourse | |||||
| According to position | 0.001‡ | 0.001‡ | |||
| No UAI | 4.01 | 1 | 1 | ||
| Insertive only | 5.26 | 1.39 (0.80 to 2.41) | 1.13 (0.65 to 1.99) | ||
| Receptive withdrawal | 12.82 | 3.24 (2.13 to 4.92) | 2.62 (1.69 to 4.06) | ||
| Receptive to ejaculation | 14.64 | 3.66 (2.21 to 6.06) | 2.98 (1.76 to 5.02) | ||
| According to partner’s HIV status | 0.001† | NA§ | |||
| No UAI | 4.01 | 1 | |||
| Negative only | 7.47 | 1.97 (1.04 to 3.75) | |||
| Some HIV unknown | 9.97 | 2.52 (1.74 to 3.66) | |||
| Some HIV positive | 15.66 | 4.35 (2.16 to 8.77) | |||
| Receptive fingering | 0.001† | 0.562† | |||
| Never | 3.61 | 1 | 1 | ||
| Occasionally | 6.76 | 1.82 (1.18 to 2.81) | 1.12 (0.71 to 1.79) | ||
| Often | 8.94 | 2.42 (1.41 to 4.15) | 1.19 (0.65 to 2.18) | ||
| Receptive fisting | 0.006† | 0.280† | |||
| Never | 5.60 | 1 | 1 | ||
| Occasionally | 13.47 | 2.40 (1.29 to 4.47) | 1.47 (0.78 to 2.77) | ||
| Often | 12.89 | 2.21 (0.31 to 15.97) | 1.22 (0.17 to 8.96) | ||
| Receptive rimming | 0.001† | 0.004† | |||
| Never | 2.32 | 1 | 1 | ||
| Occasionally | 7.14 | 3.00 (1.76 to 5.12) | 2.07 (1.19 to 3.61) | ||
| Often | 9.22 | 3.86 (2.10 to 7.11) | 2.53 (1.35 to 4.76) | ||
| Receptive of dildos | 0.064† | 0.763† | |||
| Never | 5.55 | 1 | 1 | ||
| Occasionally | 7.57 | 1.37 (0.85 to 2.21) | 0.82 (0.50 to 1.35) | ||
| Often | 14.11 | 2.42 (0.77 to 7.65) | 1.53 (0.47 to 5.03) | ||