Table 3.
Odds Ratios for Intrapartum HIV-1 Infection According to Maternal Demographic and Clinical Characteristics.
| Characteristic | Infected | Uninfected | Odds Ratio (95% CI) | |||
|---|---|---|---|---|---|---|
| Unadjusted | P Value | Adjusted* | P Value | |||
| no./total no. (%) | ||||||
| Treatment group | ||||||
|
| ||||||
| Zidovudine plus nelfinavir and lamivudine | 12/528 (2.3) | 516/528 (97.7) | 0.49 (0.24–0.99) | 0.047 | 0.50 (0.24–1.01) | 0.05 |
|
| ||||||
| Zidovudine plus nevirapine | 11/534 (2.1) | 523/534 (97.9) | 0.44 (0.21–0.91) | 0.03 | 0.39 (0.19–0.82) | 0.01 |
|
| ||||||
| Zidovudine | 24/529 (4.5) | 505/529 (95.5) | 1.00 | 1.00 | ||
|
| ||||||
| Age | ||||||
|
| ||||||
| 13–24 yr | 20/627 (3.2) | 607/627 (96.8) | 0.85 (0.45–1.60) | 0.61 | ||
|
| ||||||
| 25–29 yr | 8/437 (1.8) | 429/437 (98.2) | 0.48 (0.21–1.11) | 0.08 | ||
|
| ||||||
| ≥30 yr | 19/507 (3.7) | 488/507 (96.3) | 1.00 | |||
|
| ||||||
| Race | ||||||
|
| ||||||
|
| ||||||
| Black | 29/776 (3.7) | 747/776 (96.3) | 1.56 (0.73–3.32) | 0.25 | ||
|
| ||||||
| Mixed | 9/425 (2.1) | 416/425 (97.9) | 0.87 (0.34–2.21) | 0.77 | ||
|
| ||||||
| White or other | 9/370 (2.4) | 361/370 (97.6) | 1.00 | |||
|
| ||||||
| Illegal-substance use during pregnancy | 7/137 (5.1) | 130/137 (94.9) | 1.87 (0.82–4.25) | 0.14 | 2.51 (1.08–5.86) | 0.03 |
|
| ||||||
| Increased log10 viral load | 2.16 (1.49–3.13) | <0.001 | 2.28 (1.56–3.35) | <0.001 | ||
|
| ||||||
| Increased CD4+ count | 0.90 (0.81–1.01) | 0.08 | ||||
|
| ||||||
| Prenatal care | ||||||
|
| ||||||
| No | 18/592 (3.0) | 574/592 (97.0) | 1.02 (0.56–1.86) | 0.94 | ||
|
| ||||||
| Yes | 29/974 (3.0) | 945/974 (97.0) | 1.00 | |||
|
| ||||||
| Use of zidovudine during labor | ||||||
|
| ||||||
| No | 29/931 (3.1) | 902/931 (96.9) | 1.11 (0.61–2.02) | 0.73 | ||
|
| ||||||
| Yes | 18/640 (2.8) | 622/640 (97.2) | 1.00 | |||
|
| ||||||
| Syphilis | ||||||
|
| ||||||
| Yes | 3/134 (2.2) | 131/134 (97.8) | 0.71 (0.22–2.31) | 0.57 | ||
|
| ||||||
| No | 44/1403 (3.1) | 1359/1403 (96.9) | 1.00 | |||
|
| ||||||
| Region | ||||||
|
| ||||||
| Americas | 30/1124 (2.7) | 1094/1124 (97.3) | 0.69 (0.38–1.27) | 0.24 | ||
|
| ||||||
| South Africa | 17/447 (3.8) | 430/447 (96.2) | 1.00 | |||
|
| ||||||
| Type of delivery | ||||||
|
| ||||||
| Cesarean before membrane rupture | 7/373 (1.9) | 366/373 (98.1) | 0.56 (0.25–1.27) | 0.17 | ||
|
| ||||||
| Vaginal or cesarean after membrane rupture or timing unknown | 40/1217 (3.3) | 1177/1217 (96.7) | 1.00 | |||
|
| ||||||
| Gestational age | ||||||
|
| ||||||
| 32–36 wk | 6/165 (3.6) | 159/165 (96.4) | 1.28 (0.53–3.05) | 0.59 | ||
|
| ||||||
| ≥37 wk | 41/1426 (2.9) | 1385/1426 (97.1) | 1.00 | |||
All available demographic and clinical variables were tested for their association with transmission. P values are for the significance of the association with transmission from mother to infant. All variables with a P value of 0.20 or less were included in the multivariable regression model. Variables with a P value of more than 0.20 were then removed from the model. The backward-elimination method was used to select the final model. This model used maternal viral load and maternal CD4+ count as continuous variables in addition to treatment group and illegal substance use. The odds ratios shown for log10 viral load and CD4+ count are associated with a 1-log increase in the viral load or a 100-cell increase in the CD4+ count. The CD4+ count was eliminated from the final adjusted model.