Transcript Principles of Internal Quality and External Quality Assurance

Principles of Internal Quality
and
External Quality Assurance
Dr Kapil Yadav, Prof MG Karmarkar,
International Council for Control of Iodine Deficiency
Disorders (ICCIDD),
All India Institute of Medical Sciences (AIIMS), New Delhi
25th February, 2010
Quality Assurance (QA) and
Quality control (QC)
• Two terms used interchangeably though their
meanings differ.
• Quality assurance is a proactive and continuous
process of monitoring a system for reproducibility and
reliability by:
1. Setting standards of performance & designating
responsibility
2. Ensuring definitive corrective actions are taken when the
criteria not met
3. Performing measurements within a stated level of
confidence
Quality Control (QC)
• A quality control system is an indicator system
for documented performance and actions
that:
1. Provides a record of consistency of performance
2. Records action taken when performance fails to
meet standard
• Thus quality control is tool by which the
principle of quality assurance is achieved.
Elements of QA system
• An inventory agency responsible for
coordinating QA/QC activities;
• A QA/QC plan;
• General QC procedures;
• Functions of participants
• Reporting, documentation, and archiving
procedures.
Internal Quality Assurance
• Steps taken by the implementing
laboratory to ensure that the
process/system used by them
to estimate salt iodine content are
consistent and operate with a specified
level of confidence.
External Quality Assurance
• Steps taken by an external review agency
to ensure that the process/system used
by the implementing laboratory to
estimate salt iodine content are
consistent and operate with a specified
level of confidence.
Steps in Internal Quality Assurance: 1
• Step1: Preparation of known value samples
• Step 2: Analysis of known value sample with
every batch of salt to be tested.
• Step 3: Plotting Levy Jenning (L J) plot.
Levy Jenning Plot
Levy Jenning Plot
5
4
3
+ SD
50
P
2
40
1
Mean
P
30
0
-1
- SD
20
-2
-3
10
-4
0
-5
0
1
2
3
4
Day of Month
5
6
7
M
of I2
Levy Jenning Plot
Name of Laboratory
Reporting Month
Known value salt preparation
Test No. Value
1
34
2
34
3
36
4
31
5
32
6
35
7
36
8
29
9
31
10
35
Known value Mean
33.3
Known value SD
2.41
Day of Month
Value
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
1
2
3
32
33
34
35
31
32
31
33
34
33
32
33
32
32
29
34
32
31
29
ValueMean/SD
-0.54031
-0.12469
0.290938
0.706564
-0.95594
-0.54031
-0.95594
-0.12469
0.290938
-0.12469
-0.54031
-0.12469
-0.54031
-0.54031
-1.78719
0.290938
-0.54031
-0.95594
-1.78719
Value- Mean/SD
4
3
2
1
0
-1
-2
-3
-4
1
4
7 10 13 16 19 22 25 28 31
Steps in Internal Quality Assurance: 2
• Step 4: Monitoring and feedback based on
results of L J plot.
• Step5: Fixed number of samples to be
collected randomly on different days and
analyzed in duplicate.
Steps in Internal Quality Assurance: 3
• Step6: Salt samples along with the results to
be sent to the reference laboratory each
month (at least 50gms for each sample).
• Step7: The reference laboratory will analyze
these salt samples in duplicate and then
compare the results with the values obtained
by laboratory which sent the samples.
Steps in External Quality Assurance: 1
• Step 1: The reference laboratory will analyze
six salt samples (different brands) purchased
from the market, six times each.
• Step 2: Find the Mean and the Standard
Deviation for each salt sample.
• Step 3: Reference laboratory will send 50 gms
of each salt sample to the participating
laboratory each month.
Steps in External Quality Assurance: 2
• Step 4: Participating laboratory will analyze
these salt samples in duplicate and send the
results to reference laboratory.
• Step 5: Reference laboratory then will compile
the results, compare the values, and advise
any remedial measures.
Thank You
“Quality assurance is not a fault finding mission
but a method to ensure quality of results from
each laboratory.”