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Table 4 Bland-Altman analysis for bias and 95% confidence interval compared to SST for HAI titers

From: Influence of sample collection tube method, anticoagulant-containing plasma versus serum, on influenza virus hemagglutination inhibition titer and microneutralization titer serological assays

Collection Method

Bias, 95% Confidence

Type A, H1N1

Type A, H3N2

Type B

RT Sera

−0.1 (−1.17, 0.97)

− 0.07 (− 1.12, 0.99)

−0.25 (− 1.77, 1.27)

ACD Plasma

− 0.23 (− 1.22, 0.75)

−0.38 (− 1.4, 0.64)

−0.2 (− 1.84, 1.44)

Hep Plasma

− 0.2 (− 1, 0.6)

−0.15 (− 1.42, 1.12)

−0.2 (− 1.76, 1.36)

Cit Plasma

− 0.4 (− 2.95, 2.15)

−0.35 (− 2.23, 1.53)

−0.25 (− 2.24, 1.74)

EDTA Plasma

0.13 (− 0.86, 1.13)

0.43 (− 0.85, 1.71)

2.17 (0.17, 4.17)

  1. Dilution factor bias for each sample collection method compared to SST is shown. Negative values indicate overall lower titer values and positive values indicate overall higher titer values compared to SST. The closer the value is to zero the better the agreement between the two collection tube methods. The 95% confidence interval is also shown demonstrating the dilution factor limits of agreement between the two methods
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BMC Health Services Research

ISSN: 1472-6963

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