Table 4.
Comparing population-based and ANC sentinel-surveillance HIV prevalence estimates
| ANC based HIV prevalence estimates1 | Population based HIV prevalence estimates | Ratio of ANC and population based estimates2 | C hi2 (p)3 | |||
| All women | Crude | 37.9 | 25.2 | 1.50 | < 0.001 | |
| 15–19 | 19.5 | 6.9 | 2.83 | < 0.001 | ||
| 20–24 | 37.0 | 28.7 | 1.29 | 0.002 | ||
| 25–29 | 54.3 | 49.6 | 1.09 | 0.254 | ||
| 30–34 | 51.7 | 47.0 | 1.10 | 0.362 | ||
| 35+ | 3 6.5 | 27.7 | 1.32 | 0.053 | ||
| Age standardised | 36.2 | 27.5 | 1.32 | < 0.001 | ||
| Age & location4 | 31.7 | 27.5 | 1.15 | 0.005 | ||
| Age & catchment5 | 35.6 | 27.7 | 1.29 | < 0.001 | ||
| Nulliparous | Crude | 24.8 | 11.9 | 2.08 | < 0.001 | |
| Age standardised | 21.3 | 15.5 | 1.37 | 0.003 | ||
| Age & location4 | 20.1 | 15.9 | 1.26 | 0.037 | ||
| Age & catchment5 | 20.6 | 16.0 | 1.29 | 0.022 | ||
| Parity 1+ | Crude | 46.4 | 33.0 | 1.41 | < 0.001 | |
| Age standardised | 43.0 | 34.4 | 1.25 | < 0.001 | ||
| Age & location4 | 37.0 | 34.1 | 1.09 | 0.153 | ||
| Age & catchment5 | 41.6 | 34.5 | 1.21 | < 0.001 | ||
| Pregnant women | Crude | - | 23.8 | 1.59 | < 0.001 | |
| Age standardised | - | 25.2 | 1.44 | < 0.001 | ||
| Age & location4 | - | 25.3 | 1.25 | 0.006 | ||
| Age & catchment5 | - | 25.0 | 1.42 | < 0.001 | ||
| Clinic location (ANC); residency location (population) | Urban | Crude | 40.7 | 26.0 | 1.56 | 0.006 |
| Age standardised | 39.2 | 27.1 | 1.47 | 0.023 | ||
| Peri-urban | Crude | 36.5 | 33.5 | 1.09 | 0.277 | |
| Age standardised | 36.8 | 36.5 | 1.01 | 0.930 | ||
| Rural | Crude | 29.2 | 21.3 | 1.37 | 0.028 | |
| Age standardised | 28.5 | 23.2 | 1.22 | 0.151 | ||
| Projected clinic catchment (ANC); residence within projected clinic catchment (population) | Peri-urban/urban | Crude | 40.7 | 30.5 | 1.33 | < 0.001 |
| Age standardised | 38.2 | 33.5 | 1.14 | 0.039 | ||
| Rural/peri-Urban | Crude | 39.4 | 27.2 | 1.45 | 0.001 | |
| Age standardised | 38.2 | 29.3 | 1.30 | 0.018 | ||
| Rural | Crude | 32.0 | 20.8 | 1.54 | < 0.001 | |
| Age standardised | 32.3 | 22.7 | 1.42 | < 0.001 | ||
1 18 women excluded from the analyses with age not known
2 Ratio based on ANC totals when no direct comparable ANC group
3 Difference between two proportions (ANC-based HIV prevalence estimate compared to the population-based estimate)
4 Standardisation based on age and residency location (urban, rural and peri-urban) distribution within the ACDIS population
5 Standardisation based on age and predicted ANC clinic catchment (peri-urban/urban, peri-urban/rural and rural) distribution within the ACDIS population