Risk factors for incident urethral 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 those risk variables that were significant multivariate predictors and those sexual behaviours that could have led to exposure of the urethra to infection (insertive oral sex and UAI) 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) | 0.004† | 0.016† | |||
| <25 | 10.03 | 1 | 1 | ||
| 25–34 | 11.26 | 1.21 (0.67 to 2.17) | 1.18 (0.64 to 2.18) | ||
| 35–44 | 8.51 | 0.93 (0.52 to 1.68) | 0.96 (0.52 to 1.78) | ||
| 45–54 | 6.15 | 0.70 (0.36 to 1.38) | 0.73 (0.36 to 1.48) | ||
| >54 | 3.77 | 0.41 (0.15 to 1.16) | 0.47 (0.16 to 1.34) | ||
| Chlamydia contact | 0.001‡ | 0.001‡ | |||
| No | 7.65 | 1 | 1 | ||
| Yes | 43.58 | 5.37 (3.61 to 8.00) | 4.61 (3.07 to 6.92) | ||
| Number of casual partners in the past 6 months | 0.001† | 0.01† | |||
| 1 | 4.39 | 1 | 1 | ||
| 2–5 | 5.96 | 0.73 (0.34 to 1.55) | 1 | ||
| 6–10 | 8.50 | 1.43 (0.92 to 2.22) | 1.14 (0.72 to 1.81) | ||
| 11–50 | 10.90 | 1.81 (1.25 to 2.63) | 1.49 (1.01 to 2.19) | ||
| >50 | 15.95 | 2.73 (1.69 to 4.43) | 1.83 (1.09 to 3.06) | ||
| Unprotected anal intercourse | |||||
| According to position | 0.001‡ | 0.029‡ | |||
| No UAI | 7.61 | 1 | 1 | ||
| Insertive only | 10.72 | 1.45 (0.98 to 2.14) | 1.13 (0.75 to 1.70) | ||
| Insertive and receptive | 15.37 | 2.03 (1.42 to 2.91) | 1.61 (1.10 to 2.35) | ||
| Receptive only | 4.84 | 0.64 (0.30 to 1.38) | 0.55 (0.24 to 1.26) | ||
| According to partner’s HIV status | 0.001† | ||||
| No UAI | 7.61 | 1 | NA§ | ||
| Negative only | 4.74 | 0.69 (0.32 to 1.47) | |||
| Some HIV unknown | 12.05 | 1.56 (1.14 to 2.13) | |||
| Some HIV positive | 20.56 | 2.92 (1.61 to 5.29) | |||
| Insertive oral sex with ejaculation | 0.001† | 0.007† | |||
| Never | 6.31 | 1 | 1 | ||
| Occasionally | 12.90 | 1.96 (1.46 to 2.63) | 1.54 (1.13 to 2.11) | ||
| Often | 12.59 | 1.95 (1.06 to 3.56) | 1.65 (0.89 to 3.06) | ||