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Table 2 Concordance (coefficient kappa) and accuracy analysis between Kato-Katz test results obtained by an increasing number of slides and the results of one rapid urine test sample (POC-CCA)

From: Concordance of the point-of-care circulating cathodic antigen test for the diagnosis of intestinal schistosomiasis in a low endemicity area

POC-CCA Kato-Katz 1S 1st AS Kato-Katz 6S 3SA Kato-Katz 16S 3SA
Positive Negative Total Positive Negative Total Positive Negative Total
Positive 5 84 89 14 75 89 23 66 89
Negative 4 279 283 10 273 283 12 271 283
Total 9 363 372 24 348 372 35 337 372
Sensitivity 55.6% (95% CI: 26.6–81.1) 58.3% (95% CI: 38.8–75.5) 65.7% (95% CI: 49.1–79.1)
Specificity 76.9% (95% CI: 72.2–80.9) 78.4% (95% CI: 73.8–82.4) 80.4% (95% CI: 75.8–84.3)
PPV 6.0% (95% CI: 2.4–12.5) 16.0% (95% CI: 9.6–24.6) 26.0% (95% CI: 17.9–37.0)
NPV 98.6% (95% CI: 96.4–99.4) 96.5% (95% CI: 93.6–98.1) 95.8% (95% CI: 92.7–97.6)
Kappa index 0.06 (95% CI: 0.01–0.1) 0.16 (95% CI: 0.1–0.2) 0.27 (95% CI: 0.2–0.3)
Accuracy 76.0% (95% CI: 74.6–82.8) 77.0% (95% CI: 72.6–81.1) 79.0 79.0% (95% CI: 74.6–82.8)
  1. CI Confidence interval, PPV Positive predictive value, NPV Negative predictive value, S Slides, SA Sample, 1S 1st SA One slide of the first sample, 6S 3SA Six slides of three different samples, two slides of each sample, 16S 3SA 16 slides of three different samples, 12 slides of the first sample, two slides of the second sample and two slides of the third sample