Table 3.
Hormonal contraceptive use and risk of HIV-1 seroconversion
| Number of HIV infection/p-yrs |
Incidence | Unadjusted HR1 (95% CI) |
p-value | Adjusted HR (95% CI) |
p-value | |||
|---|---|---|---|---|---|---|---|---|
| All participants 2 | 106/2605 | 4.07 | ||||||
| No hormonal contraception | 29/481 | 3.95 | Ref | -- | -- | -- | -- | -- |
| Injectable | 72/1543 | 4.66 | 1.26 | (0.76, 2.10) | 0.37 | 1.17 | (0.70, 1.96) | 0.56 |
| Oral | 15/580 | 2.58 | 0.77 | (0.38, 1.57) | 0.47 | 0.76 | (0.37, 1.55) | 0.45 |
| Stratified by age at enrollment 3 | ||||||||
| Age <25 years | 58/1218 | 4.76 | ||||||
| No hormonal contraception | 9/172 | 5.22 | Ref | -- | -- | -- | -- | -- |
| Injectable | 38/788 | 4.82 | 1.01 | (0.48, 2.11) | 0.98 | 1.01 | (0.48, 2.11) | 0.99 |
| Oral | 11/257 | 4.29 | 0.93 | (0.37, 2.45) | 0.89 | 0.93 | (0.37, 2.35) | 0.88 |
| Age ≥ 25 years | 48/1388 | 3.46 | ||||||
| No hormonal contraception | 10/309 | 3.24 | Ref | -- | -- | -- | -- | -- |
| Injectable | 34/755 | 4.50 | 1.53 | (0.75, 3.12) | 0.24 | 1.42 | (0.70, 2.91) | 0.34 |
| Oral | 4/324 | 1.23 | 0.46 | (0.13, 1.59) | 0.22 | 0.45 | (0.13, 1.59) | 0.22 |
| Stratified by HSV-2 status at enrollment 4 | ||||||||
| HSV-2 positive | 64/1088 | 5.88 | ||||||
| No hormonal contraception | 14/224 | 6.26 | Ref | -- | -- | -- | -- | -- |
| Injectable | 41/654 | 6.27 | 0.99 | (0.54, 1.85) | 0.99 | 0.87 | (0.46, 1.63) | 0.66 |
| Oral | 9/211 | 4.27 | 0.80 | (0.33, 1.93) | 0.62 | 0.72 | (0.29, 1.75) | 0.46 |
| HSV-2 negative | 42/1517 | 2.77 | ||||||
| No hormonal contraception | 5/257 | 1.94 | Ref | -- | -- | -- | -- | -- |
| Injectable | 31/890 | 3.48 | 2.08 | (0.80, 5.38) | 0.13 | 1.96 | (0.75, 5.12) | 0.17 |
| Oral | 6/369 | 1.62 | 0.93 | (0.27, 3.24) | 0.91 | 0.94 | (0.27, 3.30) | 0.92 |
| Enrolled at South African sites 2 | 65/962 | 6.76 | ||||||
| No hormonal contraception | 10/256 | 3.91 | Ref | -- | -- | -- | -- | -- |
| Injectable | 47/551 | 8.53 | 1.93 | (0.97, 3.80) | 0.06 | 1.70 | (0.85, 3.39) | 0.13 |
| Oral | 8/156 | 5.14 | 1.24 | (0.49, 3.16) | 0.65 | 1.23 | (0.48, 3.13) | 0.67 |
P-yrs = person-years. HR= hazard ratio. CI = confidence interval.
Cox proportional hazards models stratified by site.
Adjusted model =Time-varying Cox proportional hazards models stratified by site and adjusted for baseline age (as a continuous variable), living with a partner, HSV-2 status, and time-varying unprotected sex at last vaginal sex act with censoring at the first positive pregnancy test.
Adjusted models =Time-varying Cox proportional hazards models stratified by site and adjusted for living with a partner, HSV-2 status, and time-varying unprotected sex at last vaginal sex act with censoring at first the positive pregnancy test. Likelihood ratio test for age: p=0.51.
Adjusted models =Time-varying Cox proportional hazards models stratified by site and adjusted for baseline age, living with a partner, and time-varying unprotected sex at last vaginal sex act with censoring at first positive pregnancy test. Likelihood ratio test for baseline HSV-2 status: p=0.51.