BENEFIT OF :

SIGMA METRIC IN CLINICAL LABORATORY

48.000-96.000 patients deaths/year is caused by errors ( IOM-USA)

70% of all informations used for patient care is provided by the clinical laboratory.

The challenge is to ensure “error-free”processes …, from pre-analytical, analytical, and to the post-analytical, functions of laboratory services.” ....

Primum non nocere (Galen)

QUALITY CONTROL

Internal QC

External QC

Peer Group QC

Preanalytical QC ? ACCREDITATION

KARS, KALK, ISO 15189 AUTOMATION CONTINUOUS EDUCATION AND TRAINING

The old pippettes have been replaced by large, computerized , advanced instruments,

WHY would you want to use a 50 years old QC rules on a cutting edge instruments?

INTERNAL QUALITY CONTROL

Offer methodology for measuring process performance quantitatively

If you can’t measure quality, you can’t manage it.” ( JO Westgard)

HIGH QUALITY TOP QUALITY

INTERNATIONAL QUALITY BEST QUALITY

WORLD CLASS QUALITY

1980 Introduced by Motorola 1990 Applied widely in manufacturing

industry 2000 Applied in service industry

Six Sigma : World Class Quality

6 SIGMA = WORLD CLASS

QUALITY

CURRENT SITUASION =3

SIGMA

PRA ANALYTIC

ANALYTIC

POST ANALYTIC

Lab A performance 3,5 – 4 S 1% error rate

If Patient B :-10 test :error probability 10%-2x/ week :error probability 20%

DEFECT = ERROR

IMPLEMENTATION OF SIGMA METRIC IN

CLINICAL LABORATORY

Check outcome count defects

Pre and post analytical phase

TAT < 60’ , If > 60 ‘ defects

Characterizing variation of process

Analytical phase

Quality requirement = bias + imprecisionx + quality requirement = x + (bias + 6SD)

if Bias is O (zero):

x + quality requirement = x + 6SD

6S or 6SDs of process variation should fit within quality requirement

If bias : 4mg/dL =2%CV =(Tea – Bias)/ 6

= (10-2)/6 = 1,3 %

SETTING PERFORMANCE SPECIFICATION MEASURING ANALYTICAL PROCESS

QUALITY SELECTING IQC PROCEDURE SELECTING INSTRUMENT AND METHOD

SETTING PERFORMANCE SPECIFICATION Quality Design and Control Process

Process for translating customer needs into product and production specifications

CUSTOMER NEEDS :

▪ QUICK RESULT

▪ GOOD SERVICE

▪ SAFETY

▪ CORRECT RESULT SIGMA

▪ ETC

*Preanalytical error

*Group and within subject BV

SETTING PERFORMANCE SPECIFICATION MEASURING ANALYTICAL PROCESS

QUALITY SELECTING IQC PROCEDURE SELECTING INSTRUMENT AND METHOD

Allowable Total Error (Analytical Outcome Criteria)

Clinical Decision Interval (Clinical Outcome Criteria)

Maximum allowable SD and Maximum allowable bias (analytical performance criteria)

TEa : decision interval,analytical performance, guidelines (CLIA,Biologivariation, RCPA, NCEP)

Bias : difference from true value (EQAS,Peer group, reference method)

S : CV / SD from precision study (IQC)

Sigma metric = ( TEa – Bias ) / S

RCPA CLIA AND PROFESIONAL GUIDELINE

- Choose lab quality requirement

- Document and review lab quality requirement

- Determine lab quality requirement

- Document and review lab quality requirement

.

ALP AST

• Traceability

• Measured

substance

• Method

BHCG

Daily laboratory QC :

Cover different staff, reagent lot, control and calibration

3-6 months

Based on lab mean and SD At clinical important level

Example : CHOLESTEROL

Quality requirement (Tea) 10% Bias 1% Imprecision 4.5%

Sigma = ( Tea – Bias ) / S = (10 – 1)/4.5 = 2 = (308.537 defects / million tests)

Y axis : allowable inaccuracy ( bias, %) TEa

Clinical desicion interval

X axis : allowable imprecision for certain sigma ( CV,%)

Sigma metric = ( TEa – Bias ) / S

- X axis : allowable imprecision for certain sigma ( CV,%)

Ex : Tea = 12%, Bias =0%2S : max CV = 12/2 = 6%3S : max CV = 12/3 = 4%4S : max CV = 12/4 = 3%5S : max CV= 12/5 = 2.4%6S : max CV = 12/6 = 2%

- Albumin : Tea 12%

- Bias : 3%- CV : 3 %- Sigma : 3S

SETTING PERFORMANCE SPECIFICATION MEASURING ANALYTICAL PROCESS

QUALITY SELECTING IQC PROCEDURE SELECTING INSTRUMENT AND METHOD

ANALYTICAL OUTCOME CRITERIA

(TEa)

BIAS and CV/SD

QC RULES AND CONTROL NUMBER

ACCURACY and PRECISION

CLINICAL OUTCOME CRITERIA

ELEMENTS IN ANALYTICAL QUALITY :

Imprecision

Inaccuracy

Instability of measurement procedure

QC rules

GOOD QC RULES High error detection Low false rejection Low cost

QCRULES Number of QC Level Number of Run QC Rules

TEa : decision interval,analytical performance, guidelines (CLIA,RCPA, NCEP)

Bias : difference from true value (EQAS,Peer group, reference method)

S : CV / SD from precision study (IQC)

Sigma metric = ( TEa – Bias ) / S

POTASSIUM : Quality requirement (TEa) :10% (CLIA) Lab X ,instrument Y : CV1.5%, Bias 1% Sigma metric : (TEA – Bias)/ S = (10-1)/1.5 = 6 QC Program : N=2 / 3,5 s control limit

CHOLESTEROL : Quality requirement (TEa) : 10% (CLIA) Lab A, instrument B : CV4.5%, Bias 1% Sigma : ( TEa – Bias ) / S = (10 – 1)/4.5 = 2 QC Program : Maximum N , Multirules and Max

prevention action

SIGMA

6 5 4 3

QC NO AND QC RULES

N2/3,0-3,5 S N2/2,5-3,0 s N4/Multirules Max QC with

Max supervision ,Max experience

Different parameter Easy to difficult to handle

Different QC rules for different parameter With the help of Laboratory Information

System create individualize QC rules and monitoring each parameter

INVENTORY GROUPING TROUBLE SHOOTING AND IMPROVEMENT ; Instrument

Reagen

Methods

Procedures

Staff START WITH QC RULE WITH HIGH ERROR

DETECTION

SETTING PERFORMANCE SPECIFICATION MEASURING ANALYTICAL PROCESS

QUALITY SELECTING IQC PROCEDURE SELECTING INSTRUMENT AND METHOD

SETTING PERFORMANCE SPECIFICATION MEASURING ANALYTICAL PROCESS

QUALITY SELECTING IQC PROCEDURE SELECTING INSTRUMENT AND METHOD

SELECTING INSTRUMENT AND REAGENT

Customizing to customer and laboratory

requirement

Fewer errors, Fewer number of controls, less frequent

testing of controls, simpler control rules Better analytic quality

Analysis by Sten Westgard of 2007 AACC Poster: Gough SA, et al. Site Evaluation of Abbott Architect c16000. Clin Chem Chem 2007;53(s):A228.

SIX SIGMA IN CLINICAL LABORATORY:

Determining laboratory goal Selecting instrument and method Process quality monitoring Internal Quality Control Plan Patient satisfaction and safety

THANK YOU

James O. Westgard. Six Sigma Quality Design and Control .2nd ed,Westgard QC,Inc.2006

Six Sigma .A Quality Metric for Clinical Laboratory. Abbott Workshop Series