WS/T 641-2018 English PDF (WST641-2018)

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WS/T 641-2018: Internal quality control for quantitative measurement in clinical laboratory
WS/T 641-2018
HEALTH INDUSTRY STANDARD OF
THE PEOPLE’S REPUBLIC OF CHINA
ICS 11.020
C 50
Internal quality control for quantitative
measurement in clinical laboratory
ISSUED ON: DECEMBER 11, 2018
IMPLEMENTED ON: JUNE 01, 2019
Issued by: National Health and Wellness Committee of the People's
Republic.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Terms and definitions ... 4 
3 Preparation before internal quality control carried out ... 5 
4 Design of internal quality control method ... 6 
5 Actual operation of internal quality control ... 11 
6 Management of internal quality control data ... 17 
7 Quality control method of applicable patient data ... 18 
8 Comparison between laboratories for internal quality control data ... 19 
Annex A (informative) Common quality control rules and meanings ... 21 
Annex B (informative) Power function diagram method ... 23 
Annex C (informative) Operational process specifications diagram method .. 25 
Bibliography ... 27 
Internal quality control for quantitative
measurement in clinical laboratory
1 Scope
This Standard specifies the purpose of internal quality control for quantitative
measurement items in clinical laboratory, the design of internal quality control
method, the actual operation of internal quality control, the management of
internal quality control data, the quality control method based on patient data
as well as the comparison of internal quality control data between laboratories.
This Standard is applicable to the quantitative measurement in clinical
laboratory of the medical institution that carries out the clinical inspection
service.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1 quality control
a part of quality management that is committed to meeting quality requirements
[GB/T 19000-2016, 3.2.10]
2.2 internal quality control
the inspector, according to a certain frequency, continuously measure the
specific components in a stable sample; use a series of methods to analyze;
according to statistical law, infer and evaluate the reliability of the measurement
results for this batch so as to determine whether the inspection report can be
sent out; timely discover and exclude the dissatisfaction factors in quality link
2.3 quality control strategy
quality control variety, testing frequency of each variety, position of placement,
as well as rules for interpretation of quality control data and rules for
determination whether the analysis batch is under control or out of control
2.4 measurement bias [JJF 1001 5.5]
bias for short
3.3 Calibration
The instrument used to measure clinical sample shall be calibrated according
to some certain requirements. In calibration, select suitable (supporting)
calibration product. If possible, ensure that test results are traceable to
reference methods or/and reference materials. For different analysis items, it
shall, according to the characteristics, establish their own calibration
frequencies.
3.4 Quality control product
3.4.1 Characteristics
The quality control product shall have the similar or same matrix with the testing
sample of patient. The quality control product shall be uniform and stable. If
conditions permit, store the quality control product that can be used for one year
or more. The inter-bottle variability shall be less than the variation of analysis
system. If there is no commercialized quality control product, the laboratory can
make the quality control product by itself.
3.4.2 Analyte concentration in quality control product
The concentration of selected quality control product shall be within the
concentration range that is clinically meaningful.
If the fixed-value quality control product is used, the original calibration value in
the user’s manual can be only used as reference. It must be repeatedly
measured by the laboratory to determine the tentative and common mean value
as well as the standard deviation.
4 Design of internal quality control method
4.1 Quality control method selection and design form
The quality control selection form is a 3×3 form. It determines quality control
method that is applicable to nine different types of inspection procedures
(quality control rules and number of quality control results per batch N). For
single-rule fixed-limit quality control method, establish quality control selection
and design form, for example, Levey-Jennings quality control chart. For multi-
rule quality control method, establish quality control selection and design form,
for example, multi-rule quality control method. Table 1 and Table 2 respectively
show two quality control selection and design forms. The process capability of
the form row is described by medically important systematic error (ΔSEc). The
process stability of the form column is described by frequency of errors, f.
new batch number shall be determined with the currently used quality control
product. According to the results of at least 20 quality control measurements
obtained by 20 or more independent batches (excluding abnormal values or
outlying values), calculate average value as tentative mean value.
Use this tentative mean value as the central line of next month’s internal quality
control diagram for internal quality control. After one month, gather the under-
control results of this month and the results of previous 20 quality control
measurements. Calculate the accumulated average (the first month). Use this
accumulated average as the average value of next month’s quality control
diagram.
Repeat the above operation process. Continue three to five months or
continuously accumulate on a monthly basis.
5.1.1.2 Setting of common mean value
Use the accumulated average number that is calculated by the first 20 data and
all data collected by 3~5 months’ under-control data AS the common mean
value of quality control product within validity period. And use it as the average
number for future internal quality control diagram. For the individual item that
the concentration level continuously changes within validity period, the average
value needs adjusting constantly.
5.1.2 Quality control product of short stability
Within 3~4 days, analyze 3~4 bottles per level of quality control products every
day. Repeat 2~3 times per bottle. After data collection, calculate the average
number, standard deviation and coefficient of variation. Inspect the abnormal
value to data. If an abnormal value is found, it needs to recalculate the average
number and standard deviation of the rest data. Use this mean value as the
central line of quality control diagram.
5.2 Setting of control limit
For quality control product that has new batch, it shall determine the control
limit. The control limit is usually represented by the standard deviation multiple.
5.2.1 Quality control product of long stability
5.2.1.1 Setting of tentative standard deviation
To determine the standard deviation, the quality control product that has new
batch number shall be tested together with the currently used quality control
product. According to the results of at least 20 quality control measurements
obtained by 20 or more independent batches (excluding abnormal values or
outlying values), calculate the standard deviation and use it as tentative
5.3.2 Frequency of quality control product inspection
Within each analysis batch, at least perform one inspection for...