HBV screening in blood donors from Kumasi, Ghana
| Period of testing . | Test* . | Number of samples tested . | Positive results (%) . | Prevalence, %† . | Specificity, %‡ . | Sensitivity, %1-153 . |
|---|---|---|---|---|---|---|
| 2000 | Latex agglutination | 7543 | 723 (9.6) | 8.2 | 97.0 | 53.8 |
| 7/01-12/01 | Dipstick | 3770 | 427 (11.3) | 10.8 | 99.4 | 71.0 |
| 10/99-3/00 | Murex EIA | 3587 | 548 (15.3) | 14.7 | 99.3 | 96.6 |
| Period of testing . | Test* . | Number of samples tested . | Positive results (%) . | Prevalence, %† . | Specificity, %‡ . | Sensitivity, %1-153 . |
|---|---|---|---|---|---|---|
| 2000 | Latex agglutination | 7543 | 723 (9.6) | 8.2 | 97.0 | 53.8 |
| 7/01-12/01 | Dipstick | 3770 | 427 (11.3) | 10.8 | 99.4 | 71.0 |
| 10/99-3/00 | Murex EIA | 3587 | 548 (15.3) | 14.7 | 99.3 | 96.6 |
Latex agglutination and dipstick were from VEDAlab (Alençon, France); EIA was from Murex/Abbott (Dartford, United Kingdom). The analytical sensitivities were 30, 5, and 0.5 ng/mL HBsAg, respectively.
Confirmation of latex agglutination and dipstick was with Murex/Abbott EIA; EIA results were confirmed with an alternative HBsAg EIA (Biokit, Barcelona, Spain). The differences in prevalence between dipstick and agglutination assays and between EIA and dipstick are both significant (P < .0001).
To calculate specificity, the number of confirmed positive samples was extrapolated from the percentage of confirmed samples from a subset of samples effectively submitted to confirmation by EIA to the total sample number. This percentage was 85.6% (119 of 129) for agglutination and 96.2% (125 of 130) for EIA.
Sensitivity was calculated on the basis of 100% true positive being the number of confirmed EIA-positive samples plus 0.5% corresponding to the additional confirmed DNA-positive HBsAg-negative samples (see “Results‘).