Table 3.
Sensitivity (n = 390), specificity (n = 1043) and cost of various combinations of rapid HIV assays
| S/N | 1st Assay | 2nd Assay | Sensitivity % (95% CI) | Specificity % (95% CI) | Cost per algorithm (US$) |
|---|---|---|---|---|---|
| 1 | SD Bioline | First Response | 100 (99.1–100) | 99.9** (99.5–99.9) | 0.47 + 0.65 = 1.12 |
| 2 | First Response*** | SD Bioline | 99.5 (98.2–99.9) | 100 (96–99.1) | 0.65 + 0.47 = 1.12 |
| 3 | SD Bioline | Determine | 100 (99.1–100) | 100* (96–99.1) | 0.47 + 0.80 = 1.27 |
| 4 | Determine | SD Bioline | 100 (99.1–100) | 100* (96–99.1) | 0.80 + 0.47 = 1.27 |
| 5 | SD Bioline | Stat-Pak Dipstick | 100 (99.1–100) | 100* (96–99.1) | 0.47 + 0.80 = 1.27 |
| 6 | Stat-Pak Dipstick*** | SD Bioline | 97.9 (96–99.1) | 100 (96–99.1) | 0.80 + 0.47 = 1.27 |
| 7 | Determine | First Response | 100 (99.1–100) | 100* (96–99.1) | 0.80 + 0.65 = 1.45 |
| 8 | First Response*** | Determine | 99.5 (98.2–99.9) | 99.9 (99.5–99.9) | 0.65 + 0.80 = 1.45 |
| 9 | First Response*** | Stat-Pak Dipstick | 99.5 (98.2–99.9) | 100 (96–99.1) | 0.65 + 0.80 = 1.45 |
| 10 | Stat-Pak Dipstick*** | First Response | 97.9 (96–99.1) | 100 (96–99.1) | 0.80 + 0.65 = 1.45 |
| 11 | Determine | Stat-Pak Dipstick | 100 (99.1–100) | 100* (96–99.1) | 0.80 + 0.80 = 1.60 |
| 12 | Stat-Pak Dipstick*** | Determine | 97.9 (96–99.1) | 100 (96–99.1) | 0.80 + 0.80 = 1.60 |
| 13 | SD Bioline | Uni-Gold™ | 100 (99.1–100) | 100* (96–99.1) | 0.47 + 1.80 = 2.27 |
| 14 | Uni-Gold™ | SD Bioline | 100 (99.1–100) | 100* (96–99.1) | 1.80 + 0.47 = 2.27 |
| 15 | Uni-Gold™ | First Response | 100 (99.1–100) | 100* (96–99.1) | 1.80 + 0.65 = 2.45 |
| 16 | First Response*** | Uni-Gold™ | 99.5 (98.2–99.9) | 100 (96–99.1) | 0.65 + 1.80 = 2.45 |
| 17 | Uni-Gold™ | Stat-Pak Dipstick | 100 (99.1–100) | 100* (96–99.1) | 1.80 + 0.80**** = 2.6 |
| 18 | Stat-Pak Dipstick*** | Uni-Gold™ | 97.9 (96–99.1) | 100 (96–99.1) | 0.80 + 1.80 = 2.60 |
| 19 | Determine | Uni-Gold™ | 100 (99.1–100) | 100* (96–99.1) | 0.80 + 1.80 = 2.60 |
| 20 | Uni-Gold™ | Determine | 100 (99.1–100) | 100* (96–99.1) | 1.80 + 0.80 = 2.60 |
*Combination of the two assays had no concordant false positive results.
**One sample was repeatedly concordantly false positive in the two assays.
***The first test had initial suboptimal sensitivity (< 100%).
****Cost of Stat-Pak Dipstick is indicated as a range 0.8–0.95 US$. The best case scenario of the lowest possible cost for this test was assumed in computing the cost for algorithms involving use of Stat-Pak Dipstick.