Erythrocyte Sedimentation Rate (ESR) Abnormal Control Retrospective Analysis Project

Submitted By: Ami Desai

Project Year: 2018

Project Team Members: Ami Desai – Clinical Laboratory Scientist

Organization/ Location: California, USA

Type of Laboratory: Clinical Laboratory

Project Problem(s)/ Process Failure(s): Identify a new mean and reference range (Manufacturer’s Mean = 58; Range = 40 – 76) for the Accu-Sed® Plus Abnormal ESR Control (Ref DS-71003) due to a downward trend and several failed results.

Instruments: Excyte® 20 from ELITechGroup

Project Objective(s)/ Goal(s):

  • Attempt to improve accuracy and precision of the control values (Manufacturer Mean = 58 mm/hr, Reference range = 40-76 mm/hr).

Project Design:

  • Retrospective analysis of previous abnormal control results for this lot of abnormal control.

Project Steps:

  • Retrospective Analysis
    • Since the current lot of controls has been in use since September 2017, performed a retrospective analysis of 20 sets of controls tested during different dates by different clinical laboratory scientists (CLSs).
  • Establish New Mean and Reference Range
    • Used the 20 sets of results to establish a new mean and reference range.

Results/ Lessons Learned:

  • Normal Control
    • Mean = 5.95 mm/hr
    • SD = 0.6 mm/hr
    • CV = 10.08%
    • Range = 4.0 – 8.0 mm/hr
      • 1SD = 5.35 – 6.55 mm/hr
      • 2SD = 4.75 – 7.15 mm/hr
  • Abnormal Control
    • Mean = 44 mm/hr
    • SD = 4.3 mm/hr
    • CV = 9.80%
    • Range = 35.0 – 53.0 mm/hr
      • 1SD = 39.7 – 48.3 mm/hr
      • 2SD = 35.4 – 52.6 mm/hr

Comments:

Past practice when receiving a new lot of ESR controls involved using the manufacturer’s mean and reference range. Upon the departure of the former hematology supervisor, I initiated an investigation to identify why the ESR abnormal control consistently provided results at the lower end of the reference range. Upon further investigation, the package insert states the following:

Expected control ranges are provided for the ESR methods listed in the assay table. These ranges are based on data generated by a single laboratory. Variation in interlaboratory results will be greater than the imprecision from any single laboratory. Results can also vary depending on differences in equipment, reagents, temperature, supplies and techniques.

Each laboratory should establish its own intralaboratory mean and standard deviation for each lot of ESR Control according to its own established procedures. Subsequent results should fall within the control ranges established from these statistical parameters.

Moving forward, when a new lot of ESR controls is received, 20 replicates of the normal and abnormal controls will be tested to establish a mean and reference range in keeping with good laboratory practice.

Improvements

  • Established a more robust reference range, which is tighter than the manufacturer’s reference range, to reflect laboratory-specific conditions and effectively detect clinically significant changes in the quality of the results.
    • Post-project Review
      • 20 data points
      • Mean = 45.2 mm/hr
  • Minimized the usage and subsequent waste of control due to failures.
  • Incorporated a QC plan that is lot specific.

References

  1. Accu-Sed® Plus Abnormal ESR Control Kit [package insert]. Logan, UT: ELITechGroup Inc; 2016.