Table 1 CD4 T cell counting in absolute cells/μl and percentage in 182 HIV-1-infected adults and 76 HIV-1-infected children older than 5 years, by the Apogee Auto40 flow cytometer at the hôpital Militaire D’Instruction, N’Djamena, Chad, and by the FACSCalibur at the hôpital de la Liberté, N’Djamena

Absolute CD4 T cells (cells/ μl)

Apogee Auto40

Mean ± SD

627 ± 591

1432 ± 821

FACSCalibur

Mean ± SD

635 ± 588

1449 ± 835

Absolute bias (limits of agreement)^a

Mean (±1.96 SD)

−16.0 (−38.2;6.1)

30.0 (−14.7;88.7)

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

Mean (±1.96 SD)

1.0 (−1.8;3.8)

0.3 (−2.2;2.7)

Percentage of CD4 T cells (%CD4)

Apogee Auto40

Mean ± SD

29.1 ± 12.8

32.1 ± 10.1

FACSCalibur

Mean ± SD

28.5 ± 12.5

32.3 ± 10.6

Absolute bias (limits of agreement)^a

Mean (±1.96 SD)

−3.0 (−7.1;1.1)

1.0 (−0.4;2.4)

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

Mean (±1.96 SD)

−11.0 (−25.8;3.8)

3.0 (−1.3;5.3)