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Change explorer · Haematology and immunology

Point-of-care mean cell volume (MCV) vs a central laboratory haematology analyser

Public dataBuilt from a published open-access study.

Central lab haematology analyser compared with point of care haematology analyser: 201 paired results from a published study by Shean and Bennett (2026), re-analysed by NakedSignal as if one laboratory had switched from the first system to the second. At 80, 100 fL, 26 results fall in a different category on the second system than on the first, against about 6 expected from repeat testing alone. That expected count uses a default repeat-test imprecision, the setting our program uses when no precision data are supplied, not one measured in this study, so the two numbers are not a test of whether the switch moves more results than repeat testing would.

Haematology and immunology

Mean cell volume, fL

Central lab haematology analyser compared with Point of care haematology analyser. 201 paired results.

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Comparison line

The new system reads 3.8% lower than the old system on average. The comparison line (Passing-Bablok) has a slope of 0.889 (95% interval 0.819 to 0.954) and an intercept of 7.143.

Public data
Comparison line, mean cell volume (fL)Comparison line with slope 0.889 (95% interval 0.819 to 0.954) and intercept 7.143, drawn against the line of no change. Decision limits drawn at 80, 100 fL. Where the comparison line sits above the line of no change, the new system reads higher; below, lower.40608010012040608010012080100No changeComparison lineOld system, fLNew system, fL

Fig. 1. The comparison line against the line of no change, over the range of the decision limits (80, 100 fL). Dots mark where each line meets each limit; the gap between them is the bias at that limit.

Crossing each limit

Results that fall on the other side of a decision limit on the new system than on the old, read as if the new system had 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 (80, 100 fL)

Crossed between the two systems: 26

Expected from repeat testing alone: about 6

Grade and warnings

  • Re-test band: full (at least the protocol minimum of pairs).
  • Band half-width around each limit: 2.55%.
  • Results re-tested on data the band was not fitted to, median: 15%.
  • Share of the excess crossings caught on unseen data, comparison line and band together: 89%; comparison line alone: 56%. The excess is the crossings above what repeat testing alone would cause, so the share can exceed 100% or fall below zero.
  • Repeat-test imprecision: default value.

Source

Shean RC, Bennett ST (2026). Clinical Evaluation of a Novel Point-of-Care Hematology Analyzer for Complete Blood Count With Differential. Int J Lab Hematol. doi:10.1111/ijlh.70032 (opens in a new tab); PMC12956494 (opens in a new tab). Licence: CC BY 4.0 (opens in a new tab). Re-analysed by NakedSignal. The deposit names the systems.

Show the numbers
All values for mean cell volume, Central lab haematology analyser to Point of care haematology analyser
FieldValue
Paired results used201
Comparison line slope0.889031
Slope, 95% interval0.819243 to 0.953519
Comparison line intercept7.142965
Mean difference, new minus old, as % of old-3.764
Decision limits (fL)80, 100
Crossed between the two systems26
Expected from repeat testing alone6.19
Band half-width (%)2.55
Re-tested, unseen data, median (%)14.93
Re-tested, unseen data, range (%)13.93 to 15.92
Excess caught, line and band (%)89.42
Excess caught, line alone (%)55.54

Related

Other comparisons from the same study:

Guide: Crossings by chance

Every study behind the explorer, with its licence: public data. How the counts are made: how it works.

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