Table 1 Summary of Deming regression and Bland–Altman analyses comparing the measurements of absolute CD4 cell counts (AbsCD4) between the BD FACSPresto system and the reference standard (BD Tritest kit and BD FACSCalibur system).
BD FACSPresto using venous blood sample vs BD Tritest/FACSCalibur using venous blood sample | BD FACSPresto using capillary blood sample vs BD Tritest/FACSCalibur using venous blood sample | |||||
|---|---|---|---|---|---|---|
All N = 1033 | HIV-positive group N = 402 | HIV-negative group N = 631 | All N = 1016 | HIV-positive group N = 390 | HIV-negative group N = 626 | |
Deming regression | ||||||
Intercept | 4.2 | 2.3 | 8.3 | 7.6 | 5.1 | 16.0 |
Slope | 0.95 | 0.96 | 0.94 | 0.97 | 0.99 | 0.95 |
97.5% CI of slope | 0.94–0.96 | 0.95–0.97 | 0.92–0.95 | 0.96–0.99 | 0.96–1.01 | 0.93–0.98 |
R2 | 0.984 | 0.982 | 0.960 | 0.967 | 0.965 | 0.909 |
P value | < 0.001* | < 0.001* | < 0.001* | < 0.001* | < 0.001* | < 0.001* |
Absolute deviation | ||||||
Mean ± SD | − 32.4 ± 57.9 | − 19.9 ± 47.9 | − 40.4 ± 62.2 | − 13.5 ± 82.8 | − 3.0 ± 69.2 | − 20.1 ± 89.7 |
95% CI | − 35.9 to − 28.9 | − 24.6 to − 15.2 | − 45.2 to − 35.5 | − 18.6 to − 8.4 | − 9.9 to 3.9 | − 27.1 to − 13.0 |
Within mean ± 1.96 SD | 970 (93.9%) | 381 (94.8%) | 592 (93.8%) | 961 (94.6%) | 364 (93.3%) | 593 (94.7%) |
Relative deviation | ||||||
Mean ± SD | − 4.05 ± 8.02 | − 2.99 ± 8.97 | − 4.76 ± 7.29 | − 0.62 ± 11.95 | 0.92 ± 12.85 | − 1.58 ± 11.25 |
95% CI | − 4.54 to − 3.56 | − 3.87 to − 2.11 | − 5.29 to − 4.16 | − 1.35 to 0.12 | − 0.36 to 2.20 | − 2.46 to − 0.69 |
Within mean ± 1.96 SD | 988 (95.6%) | 382 (95.0%) | 601 (95.2%) | 967 (95.2%) | 370 (94.9%) | 594 (94.9%) |
