Table 2.
Risk factors* for early (<4 months) and late (>4 months) postnatal HIV transmission among infants born to HIV-infected women in Lusaka, Zambia
| Early transmission N=37/839 | Late transmission† N=54/695 | |||
|---|---|---|---|---|
| Relative Hazard (95% CI) | Relative Hazard (95% CI) | |||
| Unadjusted | Adjusted | Unadjusted | Adjusted | |
| HIV-1 concentrations in breast milk at 4 months | ||||
| HIV-1 RNA | ||||
| >500 copies/ml | 19.25 (4.43–83.75) | 10.32 (4.88–21.86) | ||
| 50–500 copies/ml | 7.82 (1.52–40.33) | 3.83 (1.60–9.13) | ||
| < 50 copies/ml | 1.0 | 1.0 | ||
| HIV-1 RNA log copies/ml (continuous) | 2.74 (1.90–3.95) | 2.37 (1.54–3.66) | 2.93 (2.18, 3.95) | 2.09 (1.49, 2.95) |
| HIV-1 DNA | ||||
| > 1 copies/ml | 3.66 (1.33–10.06) | 2.79 (1.29, 6.04) | ||
| Undetectable | 1.0 | 1.0 | ||
| HIV-1 DNA log copies/ml (continuous) | 2.12 (1.31–3.45) | 1.52 (1.04, 2.23) | ||
| HIV-1 DNA / cell equivalents | ||||
| > 1 copies/1 million cell equivalents | 3.20 (1.16 – 8.81) | 2.99 (1.34, 6.65) | ||
| Undetectable | 1.0 | 1.0 | ||
| HIV-1 DNA log copies/1M cell equivalents (continuous) | 1.45 (1.09–1.93) | 1.44 (1.15, 1.82) | ||
| HIV-1 concentrations in breast milk at 4.5 months | ||||
| HIV-1 RNA | n/a | |||
| >500 copies/ml | 6.56 (3.07, 13.99) | |||
| 50–500 copies/ml | 1.99 (0.77, 5.15) | |||
| < 50 copies/ml | 1.0 | |||
| HIV-1 RNA log copies/ml (continuous) | 2.37 (1.74, 3.23) | |||
| HIV-1 DNA | n/a | |||
| > 1 copies/ml | 2.34 (1.16, 4.74) | |||
| Undetectable | 1.0 | |||
| HIV-1 DNA log copies/ml (continuous) | 1.90 (1.21, 2.97) | |||
| HIV-1 DNA / cell equivalents | n/a | |||
| > 1 copies/1 million cell equivalents | 2.56 (1.23, 5.32) | |||
| Undetectable | 1.0 | |||
| HIV-1 DNA log copies/1 million cell equivalents (continuous) | 1.32 (1.08, 1.62) | |||
| Feeding Characteristics | ||||
| Non-exclusive breastfeeding‡ | 2.90 (1.43–5.88) | 3.06 (1.19–7.85) | N/A | N/A |
| Exclusive Breastfeeding | 1.0 | |||
| Any breast problems‡ | 3.27 (1.16–9.25) | 1.19 (0.16, 8.81) | ||
| Maternal factors | ||||
| CD4+ T cell counts | ||||
| <350 cells/mm3 | 8.21 (2.91–23.17) | 5.37 (2.76, 10.43) | ||
| >350 cells/mm3 | 1.0 | 1.0 | ||
| CD4 cell count (on continuous scale per 100 cells/mm3) | 0.52 (0.40–0.67) | 0.57 (0.40–0.83) | 0.59 (0.49, 0.71) | 0.69 (0.55, 0.87) |
| Plasma HIV-1 RNA | ||||
| >50,000 copies/ml | 5.73 (2.62–12.53) | 4.60 (2.53, 8.38) | ||
| <50,000 copies/ml | 1.0 | 1.0 | ||
| Plasma HIV-1 RNA log copies/ml (continuous scale) | 3.72 (2.15–6.46) | 3.19 (2.05, 4.96) | 1.96 (1.11, 3.46) | |
| Maternal hemoglobin | ||||
| < 10 g/dL | 2.16 (1.13–4.15) | 1.94 (1.11, 3.39) | ||
| > 10 g/dL | 1.0 | 1.0 | ||
| Rapid Plasma Reagin status during pregnancy§ | ||||
| Positive | 2.53 (1.24–5.14) | 5.00 (2.10–11.93) | 0.84 (0.40, 1.79) | |
| Negative | 1.0 | 1.0 | ||
| Infant factors | ||||
| Birth weight (grams) | ||||
| <2500 | 2.31 (1.01–5.28) | 1.92 (0.90, 4.08) | ||
| >2500 | 1.0 | 1.0 | ||
*
Calculated using Cox Proportional Hazards models. Adjusted relative hazards are from multivariable models adjusting simultaneously for the variables shown.
†
Follow-up time was censored 30 days after cessation of breastfeeding for late transmission only
‡
Coded as a time-dependent covariates
§
A dummy variable for missing Rapid Plasma Reagin results (screening test for syphilis) (n=47) was included in the model