Location [Reference] | Data collection year(s) | Sampling approach | Participation rate | Sample size (n) | Number of HIV-positive | Population HIV prevalence as % (95% CI)* | Power of sample size to detect difference from antenatal HIV prevalence at 95% confidence level† | Comments |
---|---|---|---|---|---|---|---|---|
Tamil Nadu: 3 districts [7] | 1998 | 90 rural & urban clusters selected using probability proportional to size; selected households from each cluster invited for medical camp; first 25 adults 15–45 years old from each cluster who came to camp included in study | 82.5% for selected households; not mentioned for eligible individuals | 1981 | 34 | Age & sex adjusted: 1.80 (0.89–2.71) | 17% to detect 20% difference from 1% antenatal HIV prevalence | Selection bias likely due to medical camp sampling approach, making interpretation difficult; Grossly underpowered for reliable comparison with antenatal HIV prevalence |
Tamil Nadu: 1 rural sub-district, 1 urban town [8] | 1999–2000 | 120 rural & urban clusters selected using probability proportional to size; 15–40 years old people from randomly selected households included in study | 90.9% of 3–40-year-olds; not mentioned for eligible 15–40-year-olds | 2870 | 29 | Crude: 1.01 (0.44–1.58) | 21% to detect 20% difference from 1% antenatal HIV prevalence | Grossly underpowered for reliable comparison with antenatal HIV prevalence |
Karnataka: 1 district [31,32] | 2003 | 10 villages and 20 urban blocks selected with cluster sampling using probability proportional to size; 15–49-year-olds included in study; further details not published | 59.8% of 6700 eligible 15–49-year-olds | 4008 | 118 | Crude: 2.94 (2.12–3.76) | 50% to detect 20% difference from 2.6% antenatal HIV prevalence | Poor participation rate makes interpretation difficult; Underpowered for reliable comparison with antenatal HIV prevalence |
Andhra Pradesh: 1 district [This study] | 2004–2005 | 5 subdistricts selected to represent strata in district, from which 66 rural & urban clusters selected randomly; 15–49-year-olds from randomly selected households included in study | 91.2% of 13838 eligible 15–49-year-olds | 12617 | 241 | Age, sex & rural-urban adjusted: 1.72 (1.35–2.09) | 93% to detect 20% difference from 3% antenatal HIV prevalence | Adequately powered for reliable comparison with antenatal HIV prevalence |