Haematology and immunology
CD4 absolute count, cells/µL
Flow cytometry, laboratory platform replaced by Point of care CD4 and haemoglobin analyser. 247 paired results.
Compare it with the other comparisons in the explorer
Comparison line
The new system reads 3.7% higher than the old system on average. The comparison line has a slope of 1.044 (95% interval 1.022 to 1.077) and an intercept of -0.03.
Fig. 1. The comparison line against the line of no change, over the range of the decision limits (100, 200, 350, 500 cells/µL). Dots mark where each line meets each limit; the gap between them is the bias at that limit.
Crossing each limit
Results that moved across a decision limit when the new system replaced the old, against the number repeat testing on one unchanged system would move. The program reports the count across all limits together.
All decision limits together (100, 200, 350, 500 cells/µL)
Crossed after the change: 32
Expected from repeat testing alone: about 33
Grade and warnings
- Re-test band: full (at least the protocol minimum of pairs).
- Band half-width around each limit: 6.49%.
- Results re-tested on data the band was not fitted to, median: 15%.
- Repeat-test imprecision: assumed, not measured at this site.
- Warning from the program: The change moved fewer than 5 more people across a line than repeat testing alone would; excess caught is not meaningful here.
Source
Sagnia B, Mbakop Ghomsi F, Moudourou S, Gutierez A, Tchadji J, Sosso SM, Ndjolo A, Colizzi V (2024). Accurate and reproducible enumeration of CD4 T cell counts and Hemoglobin levels using a point of care system: Comparison with conventional laboratory based testing systems in a clinical reference laboratory in Cameroon. PLoS One. doi:10.1371/journal.pone.0297790 (opens in a new tab); PMC10954178 (opens in a new tab). Licence: CC BY 4.0 (opens in a new tab). Changes: Paired results re-analysed by NakedSignal's program; instruments described generically; only derived results are shown. The deposit names the systems.
Show the numbers
| Field | Value |
|---|---|
| Paired results used | 247 |
| Comparison line slope | 1.043741 |
| Slope, 95% interval | 1.021981 to 1.076633 |
| Comparison line intercept | -0.030269 |
| Mean difference, new minus old, as % of old | 3.734 |
| Decision limits (cells/µL) | 100, 200, 350, 500 |
| Crossed after the change | 32 |
| Expected from repeat testing alone | 33.04 |
| Band half-width (%) | 6.49 |
| Re-tested, unseen data, median (%) | 14.57 |
| Re-tested, unseen data, range (%) | 13.36 to 15.79 |
| Excess caught, line and band (%) | none |
| Excess caught, line alone (%) | none |