SIX SIGMA AND LEAN CONCEPT IN LABORATORY

MEDICINE

Abdurrahman COŞKUN, MDDüzce University, School of Medicine, Department of Clinical Biochemistry

Düzce-TURKEY

Six Sigma The Six Sigma was developed in the

early 1980s by Motorola Corp. to improve the products reliability

The methodology represents an evolution in quality management that is being widely implemented in business and industry in the new millennium

The Six Sigma strategy

The Six Sigma strategy measures the degree to which any process deviates from its goal

The sigma value indicates how often errors are likely to occur; the higher the higher the sigma value, the less likely it the sigma value, the less likely it is that the process will produce is that the process will produce errors.errors.

Sigma metrics

Sigma metrics are being adopted as a universal measure of quality and the performance of all processes can be characterized on the "Sigma scale."

Any process can be evaluated in terms of the number of sigma metrics that fit acceptable limits.

The process Sigma level can be calculated by dividing the allowable tolerance for the process by twice the process SD:

Sigma = Total process tolerance /

(2×process SD).

However in clinical laboratory measurements, it is straightforward to measure the sigma performance of analytical methods as formulated below:

Sigma = (TEa-bias)/CV

where TEa is the total error allowable and CV is the coefficient of variation.

Ideally, Six Sigma, or six SD, should fit within the acceptable limits of a process

-6s -5s -4s -3s -2s -1s 0s 1s 2s 3s 4s 5s 6s

-6s -5s -4s -3s -2s -1s 0s 1s 2s 3s 4s 5s 6s

T

Tests Sigma

Triglyceride 10.8

ALT 16.1

CK 26.0

TSH 10.4

The best or ‘‘world class’’ processes have a level of 6 sigma, which means that in this process fewer than 3.4 errors occur per million products or tests (with 1.5 standard deviation (SD) shift)

Sigma metric EPM without shift

EPM with shift

1.00 317400 697700

2.00 45400 308637

2.50 12419 158686

3.00 2700 66807

3.50 465 22750

4.00 63 6210

4.50 6.8 1350

5.00 0.57 233

5.50 0.038 32

6.00 0.002 3.4

6.8

3.4

In clinical laboratories, Sigma is usually calculated for the analytical phase of testing process

However the entire medical loop of the total testing process, i.e. from the clinician to the laboratory and back to the clinician consist 5 phases: Pre-pre-analytical, Pre-analytical, Analytical, Post-analytical and Post-post-analytical phases.

Phase Error Rate (%)

Pre-pre-analytical phase

12.0

Pre-analytical-phase 2.0

Analytical Phase 0.2

Post-analytical Phase 3.2

Post-post-analytical phase

5.0

Total ErrorSigma

202.4

Strooban et al 2003

Lean Concept

In patient focused quality management high level of quality itself is not adequate, the result of patients’ the result of patients’ tests should be reported within tests should be reported within the given timethe given time and in communication with the physicians.

For that reason we should combine the Lean

concept with Six Sigma to make the work faster (using Lean principles) and better (using Six Sigma principles)

Traditionally the ‘Six Sigma’ focused more on quality than the speed and the ‘Lean’ focused on the flow speed than quality improvement

The ‘four keys’ of Lean Six Sigma could be defined as: Delight patients with speed and

quality, Improve methods and processes, Work together for maximum gain, and Base decision on data and facts

Clinical laboratories, which have been used Lean Six Sigma in total quality management, decreased errors and contributed patients’ safety more than most other healthcare sectors