Table 3.
Diagnostic performance of the Kato-Katz method for T. trichiura infection
| No. of smears | No. of positive cases | No. of negative cases | Prevalence (95% CI) (%) | False negative rate (%) | GMEPG of the positive cases (1)a | Overestimation of GMEPG (%)b | GMEPG of the positive cases (2)c | GMEPG of the false negative casesc |
|---|---|---|---|---|---|---|---|---|
| 1 stool × 1 smear | 16 | 381 | 4.0 (2.1–6.0) | 20.0 | 58.0 | 94.7 | 35.0 | 15.7d |
| 1 stool × 2 smears | 17 | 380 | 4.3 (2.3–6.3) | 15.0 | 44.7 | 49.9 | 32.0 | 19.7e |
| 1 stool × 3 smears | 18 | 379 | 4.5 (2.5–6.6) | 10.0 | 36.7 | 23.3 | 30.8 | 21.9f |
| 2 stools × 1 smear | 18 | 379 | 4.5 (2.5–6.6) | 10.0 | 37.4 | 25.5 | 33.2 | 11.3g |
| 2 stools × 2 smears | 20 | 377 | 5.0 (2.9–7.2) | 0.0 | 32.0 | 7.4 | 29.8 | – |
| 2 stools × 3 smears | 20 | 377 | 5.0 (2.9–7.2) | 0.0 | 29.8 | 0.0 | 29.8 | – |
aOnly the available smears were calculated
bThe calculation was based on the GMEPG of the positive cases (1)
cAll six smears in ‘gold’ standard were calculated
dt(18) = 1.14, P = 0.270, compared to the GMEPG of the positive cases (2)
et(18) = 0.60, P = 0.554, compared to the GMEPG of the positive cases (2)
ft(18) = 0.35, P = 0.727, compared to the GMEPG of the positive cases (2)
gt(18) = 1.15, P = 0.264, compared to the GMEPG of the positive cases (2)