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Table 4 Comparing population-based and ANC sentinel-surveillance HIV prevalence estimates

From: Population and antenatal-based HIV prevalence estimates in a high contracepting female population in rural South Africa

    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 & location 4 31.7 27.5 1.15 0.005
   Age & catchment 5 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 & location 4 20.1 15.9 1.26 0.037
   Age & catchment 5 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 & location 4 37.0 34.1 1.09 0.153
   Age & catchment 5 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 & location 4 - 25.3 1.25 0.006
   Age & catchment 5 - 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. 1 18 women excluded from the analyses with age not known
  2. 2 Ratio based on ANC totals when no direct comparable ANC group
  3. 3 Difference between two proportions (ANC-based HIV prevalence estimate compared to the population-based estimate)
  4. 4 Standardisation based on age and residency location (urban, rural and peri-urban) distribution within the ACDIS population
  5. 5 Standardisation based on age and predicted ANC clinic catchment (peri-urban/urban, peri-urban/rural and rural) distribution within the ACDIS population