Table 2.
Predictors of virologic failure 24 months postpartum among HIV-positive women receiving antiretroviral therapy in Johannesburg, South Africa.
| Virologic failure | Person-years | Rate per100 PY (95% CI) | Total sample | Women with incident pregnancy | Women with prevalent pregnancy | ||
| Crude HR (95% CI) | aHR (95% CI) | aHR (95% CI) | aHR (95% CI) | ||||
| Total sample | 510 (8.1) | 10 091.5 | 5.1 (4.6–5.5) | ||||
| Timing of pregnancy | |||||||
| No recorded pregnancy | 198 (8.2) | 3870.1 | 5.1 (4.5–5.9) | 1 | 1 | ||
| Incident pregnancy | 188 (9.6) | 3284.9 | 5.7 (5.0–6.6) | 1.1 (0.9–1.4) | 1.3 (1.0–1.8) | ||
| Prevalent pregnancy | 124 (6.4) | 2936.4 | 4.2 (3.5–5.0) | 0.8 (0.7–1.0) | 0.7 (0.5–1.0) | ||
| Age at baseline | |||||||
| Under 25 | 73 (10.0) | 1085.6 | 6.7 (5.3–8.5) | 1 | 1 | 1 | 1 |
| 25–29.9 | 166 (8.8) | 2947.8 | 5.6 (4.8–6.6) | 0.8 (0.6–1.1) | 0.8 (0.6–1.1) | 0.9 (0.5–1.7) | 0.6 (0.3–1.3) |
| 30–39.9 | 257 (7.5) | 5583.2 | 4.6 (4.1–5.2) | 0.7 (0.5–0.9) | 0.7 (0.5–0.9) | 0.6 (0.4–1.1) | 0.9 (0.5–1.7) |
| 40–49.9 | 14 (5.0) | 473.2 | 3.0 (1.8–5.0) | 0.4 (0.2–0.8) | 0.3 (0.1–0.7) | 0.2 (0.1–0.8) | 0.4 (0.1–1.7) |
| Highest level of education at ART initiation | |||||||
| Primary school | 43 (9.0) | 744.2 | 5.8 (4.3–7.8) | 1 | |||
| Some secondary school | 96 (7.3) | 1974.3 | 4.9 (4.0–5.9) | 0.8 (0.6–1.2) | |||
| Grade 12 completed | 203 (8.5) | 3875.3 | 5.2 (4.6–6.0) | 0.9 (0.7–1.3) | |||
| Postmatric | 11 (8.6) | 210.5 | 5.2 (2.9–9.4) | 0.9 (0.5–1.8) | |||
| No schooling or unknown | 141 (8.0) | 2908.2 | 4.8 (4.1–5.7) | 0.8 (0.6–1.2) | |||
| Employment status at ART initiation | |||||||
| Employed | 160 (7.0) | 3777.8 | 4.2 (3.6–4.9) | 1 | 1 | 1 | 1 |
| Unemployed | 333 (9.0) | 5847.9 | 5.7 (5.1–6.3) | 1.3 (1.1–1.6) | 1.2 (0.9–1.5) | 1.0 (0.7–1.4) | 1.2 (0.8–1.9) |
| ART site | |||||||
| Clinic in hospital complex | 219 (8.4) | 4258.7 | 5.1 (4.5–5.9) | 1 | |||
| Local primary care clinic | 167 (8.4) | 3012.6 | 5.5 (4.8–6.5) | 1.1 (0.9–1.3) | |||
| NGO-run clinic | 124 (7.2) | 2819.2 | 4.4 (3.7–5.2) | 0.9 (0.7–1.1) | |||
| First ever ART regimen | |||||||
| TDF + 3TC/FTC + EFV/NVP | 130 (6.8) | 2845.0 | 4.6 (3.8–5.4) | 1 | 1 | 1 | 1 |
| ZDV + 3TC + EFV/NVP | 44 (7.2) | 1001.8 | 4.4 (3.3–5.9) | 1.0 (0.7–1.3) | 1.0 (0.7–1.6) | 0.9 (0.3–3.0) | 1.2 (0.6–2.3) |
| d4T + 3TC + EFV/NVP | 332 (8.8) | 6221.6 | 5.3 (4.8–5.9) | 1.2 (0.9–1.4) | 0.7 (0.4–1.2) | 2.3 (1.2–4.4) | 0.2 (0.1–0.8) |
| ABC + 3TC + EFV/NVP | 4 (25.0) | 23.1 | 17.3 (6.5–46.1) | 3.8 (1.4–10.3) | 0.9 (0.2–3.5) | 5.5 (1.1–27.0) | – |
| ART regimen changes by delivery/baseline | |||||||
| First-line regimen preserved | 377 (8.0) | 7600.6 | 5.0 (5.9–5.5) | 1 | 1 | 1 | 1 |
| First-line drug substitution | 74 (7.3) | 1730.9 | 4.3 (3.4–5.4) | 0.9 (0.7–1.1) | 0.8 (0.6–1.2) | 1.0 (0.7–1.5) | 0.6 (0.1–2.5) |
| Switched to second-line ART | 27 (9.3) | 446.4 | 6.0 (4.1–8.8) | 1.2 (0.8–1.8) | 0.8 (0.5–1.3) | 1.0 (0.6–1.7) | |
| Treatment interrupted | 32 (16.1) | 313.6 | 10.2 (7.2–14.4) | 2.1 (1.4–2.9) | 1.1 (0.7–1.9) | 1.2 (0.5–2.6) | 0.7 (0.2–2.9) |
| Time on ART before delivery/baseline | |||||||
| 3 months or less | 136 (7.0) | 2973.5 | 4.6 (3.9–5.4) | 1 | 1 | 1 | |
| 4–6 months | 61 (7.0) | 1333.2 | 4.6 (3.6–5.9) | 1.0 (0.8–1.3) | 1.6 (1.1–2.3) | 1.8 (1.0–3.1) | |
| 7–12 months | 59 (8.3) | 1160.5 | 5.1 (3.9–6.6) | 1.0 (0.7–1.4) | 1.4 (0.9–2.2) | 1 | 3.0 (1.4–6.2) |
| 13–24 months | 147 (10.6) | 2300.8 | 6.4 (5.4–7.5) | 1.1 (0.8–1.5) | 2.0 (1.3–3.1) | 1.8 (1.0–3.5) | |
| 25 months or longer | 107 (7.7) | 2323.5 | 4.6 (3.8–5.6) | 1.4 (1.1–1.8) | 1.7 (1.1–2.9) | 1.5 (0.7–2.9) | |
| BMI (up to 3 months before or after baseline) | |||||||
| Underweight | 15 (8.6) | 265.9 | 5.6 (3.4–9.4) | 1.1 (0.6–1.8) | |||
| Normal | 171 (8.6) | 3190.3 | 5.4 (4.6–6.2) | 1 | |||
| Overweight | 138 (7.2) | 3076.3 | 4.5 (3.8–5.3) | 0.8 (0.7–1.1) | |||
| Obese | 104 (8.2) | 2017.9 | 5.2 (4.3–6.2) | 1.0 (0.8–1.2) | |||
| Anaemic (up to 3 months before or after delivery/baseline) | |||||||
| No | 227 (7.7) | 4867.3 | 4.7 (4.1–5.3) | 1 | 1 | 1 | 1 |
| Yes | 160 (9.8) | 2537.3 | 6.3 (5.4–7.4) | 1.4 (1.1–1.7) | 1.2 (0.9–1.5) | 1.6 (1.1–2.3) | 1.0 (0.7–1.6) |
| CD4+ cell count (up to 3 months before or after delivery/baseline) | |||||||
| Under 200 | 149 (13.9) | 1637.7 | 9.1 (7.7–10.7) | 1 | 1 | 1 | 1 |
| 200–349 | 153 (9.8) | 2447.0 | 6.3 (5.3–7.3) | 0.7 (0.5–0.9) | 0.6 (0.4–0.9) | 1.1 (0.7–1.7) | 0.8 (0.5–1.4) |
| 350 or higher | 129 (5.5) | 3740.7 | 3.4 (2.9–4.1) | 0.4 (0.3–0.5) | 0.2 (0.1–0.4) | 0.4 (0.3–0.7) | 0.5 (0.3–0.9) |
| CD4+ recovery from date of ART initiation to date of delivery | |||||||
| Decline/no change | 105 (9.5) | 1684.0 | 6.2 (5.1–7.5) | 1 | 1 | 1 | 1 |
| <99 cell/μl increase | 85 (12.0) | 1098.3 | 7.7 (6.3–9.6) | 1.2 (0.9–1.7) | 1.5 (1.1–2.1) | 1.1 (0.5–2.1) | 1.6 (0.8–3.0) |
| 100–200 cell/ μl increase | 95 (8.8) | 1698.3 | 5.6 (4.6–6.8) | 0.9 (0.7–1.2) | 1.2 (0.8–1.7) | 0.7 (0.4–1.4) | 1.3 (0.6–2.6) |
| >200 cell/μl increase | 146 (7.0) | 3344.6 | 4.4 (3.7–5.1) | 0.7 (0.5–0.9) | 1.3 (0.9–2.0) | 1.0 (05–2.0) | 1.4 (0.6–3.4) |
| Unsuppressed viral load (≥50 copies/ml) up to 3 months before or after delivery (or equivalent matched time) | |||||||
| No | 97 (3.1) | 5080.1 | 1.9 (1.6–2.3) | 1 | 1 | 1 | 1 |
| Yes | 333 (16.9) | 2908.6 | 11.4 (10.2–12.7) | 6.0 (4.8–7.5) | 42.4 (20.2–89.0) | 6.1 (4.2–8.9) | 74.4 (11.6–477.5) |
3TC, lamivudine; ABC, abacavir; aHR, adjusted hazard ratio; ART, antiretroviral therapy; CI, confidence interval; d4T, stavudine; EFV, efavirenz; FTC, emtricitabine; HR, hazard ratio; NGO, nongovernmental organizations; NVP, nevirapine; PY, person-years; TDF, tenofovir; ZDV, zidovudine.