Sigma metric analyzing of XT‐4000i hematologic cellular analyzer to approve performance diagnosisKridsada Sirisabhabhorn, Supaporn Pumpa and Palakorn PuttarukMedical Technology Laboratory, Thammasat University Hospital, Pathumtani Province, Thailand 12120

Background: Application of metric analysis can support to recognize level of performance that benefit for further planning routine QC development. In generaluseful in range of 2 standardize variation (SD) is remain used in daily QC management; however which produce high costs.Objective: To investigate sigma metric performance in 5 parameters including RBC, WBC, PLT, HB and HCT using XT‐4000i hematologic analyzer.Materials/Methods: Total 360 data for 6 months of internal quality control (IQC) results from XT‐4000i (Sysmex Corporation, Kobe, Japan) cell analyzer werestored and calculated in 5 parameters performance of RBC, WBC, PLT, HB and HCT. Each parameter was done in 3 levels of concentration as low, normal and high.The result data were calculated as a percentage such as coefficient of variation (%CV) and %Bias. Data were evaluated to sigma metric with results of RIQASexternal quality assessment.Results: The result illustrated that metric measuring of WBC, HB and PLT parameters were presented over 6.0 sigma level (world class) in all 3 levels ofconcentration. The RBC parameter was shown within range interval of 5.0‐6.0 sigma level (excellent) and HCT played within range of good level (4.0‐5.0 sigma) inof all 3 concentrations. The suitable QC rule analysis for random error detection in our routine practice was 13S or 13.5s in 2 number of running for WBC, HB andPLT with 3 levels of concentration. The rules of 13S and 12.5Swere appropriated for RBC and HCT parameters in 2 numbers of running.Conclusions: The sigma metric in 5 significantly hematology parameters were set in a good through the world class and this study already proved the rules ofcontrol for using in our routine analysis. This study suggested that RBC and HCT parameters should be explored by a new way for developing QC in further.Key words: Sigma metric, XT‐4000i, Quality control, Rule

Abstract

Introduction

The cluster of daily quality control (QC) data will be like as garbage if moderator ignore tosummarize, interpret and apply for useful in handle control. The original rule as 2 SD is aconventional useful to accept QC result within range by general in laboratory. Alternative way,disadvantage of using 2 SD range to detecting error reveal increasing of rerun and budgetlosing. Hence knowledge in multi rules and sigma performance analysis are important role toresolve this problems. The generating QC data by using measurement of sigma metrics affectsto select suitable rule for QC management. So this study to searching suitable rule from sigmametrics for using in QC administration.

Materials and Methods

RBC ,WBC , HCT, HB, PLT  

Low level

Normal level

High level

%CV

Sigma = %TaE ‐ %Bias 

%CV 

Result

No. Parameters Level N % TEa[ref. 1‐4]

% Bias[RIQAS]

% CV (Average)

Sigma range Sigma level Rule

1. Red blood cell: RBC

Low 360 6 0.19 1.00 5.79‐5.88 ≥ 5 13S

Normal 360 6 0.19 1.01 5.68‐5.81 ≥ 5 13S

High 360 6 0.19 1.02 5.68‐5.82 ≥ 5 13S2. White blood 

cell: WBCLow 360 15 1.75 0.93 14.13‐14.35 >6 13S or 13.5s 

Normal 360 15 1.75 0.95 13.83‐14.07 >6 13S or 13.5s High 360 15 1.75 0.97 13.54‐13.91 >6 13S or 13.5s 

3. Hematocrit:HCT

Low 360 6 1.39 0.95 4.61‐5.18 ≥ 4 12.5S

Normal 360 6 1.39 1.02 4.26‐4.93 ≥ 4 12.5S

High 360 6 1.39 1.05 4.01‐5.01 ≥ 4 12.5S4 Hemoglobin: 

HbLow 360 7 0.25 0.99 6.75‐6.87 > 6 13S or 13.5s 

Normal 360 7 0.25 1.02 6.58‐6.72 > 6 13S or 13.5s High 360 7 0.25 1.02 6.50‐6.69 > 6 13S or 13.5s 

5 Platelet: PLT Low 360 25 3.26 0.89 23.33‐24.58 > 6 13S or 13.5s Normal 360 25 3.26 0.91 23.75‐24.09 > 6 13S or 13.5s High 360 25 3.26 0.93 23.79‐22.83 > 6 13S or 13.5s 

No. Sigmalevel

Qualify performance

Rule Number of run

1. < 3 Poor MaximumQC

4 or 6

2. < 4 Marginal MaximumQC

4 or 6

3. ≥ 4 Good 2.5S 2 or 3

4. ≥ 5 Excellent 3S 2 or 3

5. ≥ 6 World class 3S, 3.5S 2 or 3

Discussion and Conclusion

The result of sigma metric calculation wereshown follow on table 1 and sigma assessment withrules available using were shown follow on table 2.The classified data into sigma class was world class(Sigma ≥ 6) in WBC, Hb & PLT parameters following toexcellent and good performance in RBC and HCTrespectively. The rules of control selection for applyusing are 13S or 13.5s in WBC, Hb & PLT follow to 13Sand 12.5S useful with RBC and HCT respectively.

This result is successful exploring in rules ofcontrol handle benefit to develop performinganalysis and suspect in reduction of daily control re‐running due to out of 2SD range values.

References 

Table 2. The quality performance classification bysigma level and control rules administration.

Table 1. The evaluation results of sigma metric measurement in 5 hematologic parameters

1. CLIA ‐ CLIA '88 Proficiency Testing Limits, U.S. Federal Register.2. WSLH Proficiency Testing is a national, full‐service PT program located at the Wisconsin State Laboratory of Hygiene on the campus 

of the University of Wisconsin ‐Madison. (undated, approx June, 2004). For more , visitwww.slh.wisc.edu/pt.3. Wadsworth Center Clinical Laboratory Evaluation Program, Guide to Program Requirements and Services, New York State 

Department of Health (undated, approx June, 2004). For details, visit www.wadsworth.org/labcert.4. American Association of Bioanalysts Table of Grading Limits (undated, approx Oct 2005). For details, 

visit www.aab.org/pts/grdlim.htm5. Westgard JO, Klee GG. Quality management. In: Burtis CA, Ashwood ER, Bruns DE, editors. Tietz textbook of clinical chemistry. 4th   

ed. Philadelphia: Saunders; 2006.

[5] 

This study declared no conflicts and interest.

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