Table 3.
Predictors of being lost to follow-up at 24 months postpartum among HIV-positive women receiving antiretroviral therapy in Johannesburg, South Africa.
| LTFU | Person-years | Rate per 100 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 | 1482 (23.5) | 10077.4 | 14.7 (14.0–15.5) | ||||
| Timing of pregnancy | |||||||
| No recorded pregnancy | 561 (23.3) | 3873.6 | 14.5 (13.3–15.7) | 1 | 1 | ||
| Incident pregnancy | 380 (19.5) | 3281.5 | 11.6 (10.5–12.8) | 0.8 (0.7–0.9) | 1.0 (0.8–1.3) | ||
| Prevalent pregnancy | 541 (27.7) | 2922.3 | 18.5 (17.0–20.1) | 1.3 (1.2–1.5) | 1.2 (1.0–1.5) | ||
| Age at baseline | |||||||
| Under 25 | 216 (29.5) | 1073.7 | 20.1 (17.6–23.0) | 1 | 1 | 1 | 1 |
| 25–29.9 | 462 (24.6) | 2945.1 | 15.7 (14.3–17.2) | 0.8 (0.7–0.9) | 0.8 (0.7–1.0) | 1.3 (0.7–2.3) | 0.8 (0.6–1.2) |
| 30–39.9 | 741 (21.7) | 5591.9 | 13.3 (12.3–14.2) | 0.6 (0.6–0.7) | 0.7 (0.6–0.9) | 1.1 (0.6–1.8) | 0.7 (0.5–1.0) |
| 40–49.9 | 63 (22.5) | 464.9 | 13.6 (10.6–17.3) | 0.7 (0.5–0.9) | 0.9 (0.6–1.3) | 1.0 (0.4–2.2) | 0.9 (0.5–1.6) |
| Highest level of education at ART initiation | |||||||
| Primary school | 115 (24.1) | 750.7 | 15.3 (12.8–18.4) | 1 | 1 | 1 | 1 |
| Some secondary school | 414 (31.5) | 2006.4 | 20.6 (18.7–22.7) | 1.4 (1.1–1.7) | 1.5 (1.1–2.1) | 1.5 (0.8–2.9) | 1.6 (1.0–2.7) |
| Grade 12 completed | 497 (20.7) | 3884.2 | 12.8 (11.7–14.0) | 0.8 (0.7–1.0) | 0.9 (0.7–1.2) | 0.8 (0.5–1.4) | 0.8 (0.5–1.4) |
| Postmatric | 25 (19.5) | 208.7 | 12.0 (8.1–17.7) | 0.8 (0.5–1.2) | 1.1 (0.6–2.0) | 1.0 (0.4–2.5) | 1.2 (0.4–3.2) |
| No schooling or unknown | 372 (21.2) | 2855.9 | 13.0 (11.8–14.4) | 0.8 (0.7–1.0) | 1.5 (1.1–2.0) | 1.4 (0.8–2.4) | 1.5 (0.9–2.6) |
| Employment status at ART initiation | |||||||
| Employed | 491 (21.5) | 3784.9 | 13.0 (11.9–14.2) | 1 | 1 | 1 | 1 |
| Unemployed | 894 (24.1) | 5829.3 | 15.3 (14.4–16.4) | 1.2 (1.1–1.3) | 1.2 (1.0–1.4) | 1.1 (0.8–1.5) | 1.2 (1.0–1.6) |
| ART site | |||||||
| Clinic in hospital complex | 546 (21) | 4232.1 | 12.9 (11.9–14.0) | 1 | 1 | 1 | 1 |
| Local primary care clinic | 595 (30.1) | 3030.6 | 19.6 (18.1–21.3) | 1.6 (1.4–1.7) | 1.3 (1.1–1.5) | 1.5 (1.1–2.1) | 1.1 (0.7–1.7) |
| NGO-run clinic | 341 (19.8) | 2813.7 | 12.1 (10.9–13.5) | 0.9 (0.8–1.1) | 0.6 (0.5–0.7) | 0.6 (0.4–1.0) | 0.8 (0.4–1.5) |
| First ever ART regimen | |||||||
| 3TC/FTC + TDF + EFV/NVP | 634 (33.3) | 2882.8 | 22.0 (20.3–23.8) | 1 | 1 | 1 | 1 |
| ZDV + 3TC + EFV/NVP | 173 (28.2) | 977.8 | 17.7 (15.2–20.5) | 0.8 (0.7–0.9) | 0.9 (0.7–1.1) | 1.2 (0.6–2.4) | 1.3 (0.9–1.9) |
| d4T + 3TC + EFV/NVP | 672 (17.8) | 6192.0 | 10.9 (10.1–11.7) | 0.5 (0.4–0.5) | 1.1 (0.8–1.6) | 1.4 (0.6–3.1) | 1.7 (0.9–3.1) |
| 3TC + ABC + EFV/NVP | 3 (18.8) | 24.8 | 12.1 (3.9–37.5) | 0.5 (0.2–1.7) | 1.1 (0.7–1.7) | 68.3 (6.9–673.2) | |
| ART regimen changes by delivery/baseline | |||||||
| First-line regimen preserved | 1126 (25.3) | 6973.8 | 16.1 (15.2–17.1) | 1 | 1 | 1 | 1 |
| First-line drug substitution | 132 (17.6) | 1263.8 | 10.4 (8.8–12.4) | 0.6 (0.5–0.8) | 0.9 (0.7–1.1) | 0.8 (0.6–1.1) | 0.7 (0.3–1.5) |
| Switched to second-line ART | 180 (19.8) | 1514.6 | 11.9 (10.2–13.8) | 0.7 (0.6–0.8) | 1.1 (0.8–1.6) | 1.1 (0.7–1.7) | 0.3 (0.04–2.2) |
| Treatment Interrupted | 44 (22.1) | 325.2 | 13.5 (10.1–18.2) | 0.8 (0.6–1.1) | 1.1 (0.7–1.7) | 1.2 (0.6–2.4) | 2.0 (0.9–4.3) |
| Time on ART before delivery/baseline | |||||||
| 3 months or less | 553 (28.3) | 2943.8 | 18.8 (17.3–20.4) | 1 | 1 | 1 | |
| 4–6 months | 228 (26.1) | 1341.4 | 17.0 (14.9–19.4) | 0.9 (0.8–1.1) | 1.0 (0.8–1.2) | 0.8 (0.6–1.1) | |
| 7–12 months | 155 (21.8) | 1150.6 | 13.5 (11.5–15.8) | 0.7 (0.6–0.8) | 0.8 (0.6–1.1) | 1 | 0.4 (0.2–0.7) |
| 13–24 months | 269 (19.4) | 2317.1 | 11.6 (10.3–13.1) | 0.6 (0.5–0.7) | 0.8 (0.5–1.2) | 0.9 (0.6–1.4) | |
| 25 months or longer | 277 (20.1) | 2324.5 | 11.9 (10.6–13.4) | 0.6 (0.5–0.7) | 0.7 (0.4–1.2) | 0.9 (0.6–1.5) | |
| BMI (up to 3 months before or after baseline) | |||||||
| Underweight | 39 (22.3) | 264.9 | 14.7 (10.8–20.2) | 1.0 (0.7–1.4) | |||
| Normal | 464 (23.2) | 3175.4 | 14.6 (13.3–16.0) | 1 | |||
| Overweight | 457 (23.9) | 3063.6 | 14.9 (13.6–16.3) | 1.0 (0.9–1.2) | |||
| Obese | 324 (25.7) | 2031.5 | 15.9 (14.3–17.8) | 1.1 (0.9–1.3) | |||
| Anaemic (up to 3 months before or after delivery/baseline) | |||||||
| No | 611 (20.7) | 4843.7 | 12.6 (11.7–13.7) | 1 | 1 | 1 | 1 |
| Yes | 420 (25.6) | 2554.1 | 16.4 (14.9–18.1) | 1.3 (1.2–1.5) | 1.1 (1.0–1.3) | 1.1 (0.8–1.5) | 1.1 (0.9–1.4) |
| CD4+ cell count (up to 3 months before or after delivery/baseline) | |||||||
| Under 200 | 278 (25.9) | 1665.0 | 16.7 (14.8–18.8) | 1 | 1 | 1 | 1 |
| 200–349 | 372 (23.9) | 2455.5 | 15.1 (13.7–16.8) | 0.9 (0.8–1.1) | 0.9 (0.7–1.1) | 0.9 (0.6–1.4) | 0.8 (0.6–1.1) |
| 350 or higher | 514 (22.0) | 3703.5 | 13.9 (12.7–15.1) | 0.8 (0.7–1.0) | 0.9 (0.7–1.0) | 0.7 (0.5–1.1) | 1.1 (0.8–1.5) |
| Unsuppressed viral load (≥50 copies/ml) up to 3 months before or after delivery (or equivalent matched time) | |||||||
| No | 685 (22.0) | 4972.1 | 13.8 (12.8–14.8) | 1 | 1 | 1 | 1 |
| Yes | 505 (25.6) | 3059.5 | 16.5 (15.2–18.0) | 1.2 (1.1–1.4) | 1.5 (1.1–2.1) | 1.6 (1.2–2.1) | 0.9 (0.7–1.2) |
3TC, lamivudine; ABC, abacavir; aHR, adjusted hazard ratio; ART, antiretroviral therapy; CI, confidence interval; d4T, stavudine; EFV, efavirenz; FTC, emtricitabine; HR, hazard ratio; LTFU, loss to follow-up; NGO, nongovernmental organizations; NVP, nevirapine; PY, person-years; TDF, tenofovir; ZDV, zidovudine.