Categories
 
< 200 cells/μl

200 – 350 cells/μl

> 350 cells/μl


Number
 
N = 27

N = 43

N = 188


Absolute CD4 T cells (cells/
μl)*
    
Apogee Auto40

Mean ± SD

118 ± 161

278 ± 129

2990 ± 3745

FACSCalibur

Mean ± SD

100 ± 135

215 ± 103

3017 ± 3756

Absolute bias (limits of agreement)^{a}

Mean (±1.96 SD)

−4.0 (−33.8;+25.8)

10.0 (−70.0;+90.0)

12.0 (−160.7;+184.7)

Relative (%) bias (limits of agreement)^{b}

Mean (±1.96 SD)

62.0 (−134.0;+258.0)

7.0 (−27.2;+41.2)

−3.0 (−12.4;+6.4)

Percent CD4 T cells (%CD4)**
    
Apogee Auto40

Mean ± SD

10.0 ± 12.7

19.5 ± 6.3

55.1 ± 44.5

FACSCalibur

Mean ± SD

9.0 ± 11.3

18.0 ± 4.2

53.3 ± 41.7

Absolute bias (limits of agreement)^{a}

Mean (±1.96 SD)

1.0 (−1.8;+3.8)

2.0 (−2.3;+6.3)

2.0 (−3.4;+7.4)

Relative (%) bias (limits of agreement)^{b}

Mean (±1.96 SD)

6.0 (−10.3;+22.3)

7.0 (−13.2;+27.2)

2.0 (−4.6;+8.6)

 * Results in absolute CD4 T cell counts by Auto40 and FACSCalibur were correlated using the nonparametric Passing–Bablok regression analysis (< 200 cells/μl: r = 0.86, slope = 1.11, intercept = −12.0; 200 – 350 cells/μl: r = 0.68, slope = 1.31, intercept = −96.5; > 350 cells/μl: r = 0.98, slope = 1.02, intercept = −24.8);
 ** Results in percentage CD4 T cell counts by Auto40 and FACSCalibur were correlated using the nonparametric Passing–Bablok regression analysis (< 200 cells/μl: r = 0.89, slope = 1.00, intercept = 0.0; 200 – 350 cells/μl: r = 0.89, slope = 1.00, intercept = 0.0; > 350 cells/μl: r = 0.95, slope = 1.00, intercept = 0.0);
 ^{a} The Bland Altman analysis was carried out to calculate the absolute bias and limits of agreement which are the 95% confidence intervals (±1.96 × SD) of the mean bias of all paired measurements in a given category [27];
 ^{b} The Pollock analysis was carried out to calculate the relative bias and limits of agreement which are the 95% confidence intervals (±1.96 × SD) of the mean bias of all paired measurements in a given category [28].
 SD: Standard deviation.