Quality Control: Monitoring QC Data

1
Quality ControlMonitoring QC Data
Pawan Angra MS Division of Laboratory
Systems Public Health Practice Program
Office Centers for Disease Control and Prevention
2
Levey-Jennings Chart
3
Levey-Jennings Chart
3 SD
2 SD
1 SD
Mean
1 SD
2 SD
3 SD
4
Monitoring QC Data

• Meet pre-established limits, usually 95
  confidence interval
• Plot Levey-Jennings each day, make decision
  regarding acceptability
• Monitoring over time provides information about
  the precision and long-term accuracy of
  measurement
• Review charts at defined intervals

5
Control Values and Decision

• Consider using Westgard Control Rules
• Use premise that 95.5 of control values should
  fall within 2SD
• Commonly applied when two levels of control are
  used
• Use in a sequential fashion

6
Westgard Rules

• 1 2s rule
• 1 3s rule
• 2 2s rule
• R-4s rule
• 4 1s rule
• 10x rule

7
Westgard 1 2s Rule

• warning rule
• One of two control results falls outside 2SD
• Alerts tech to possible problems
• Not cause for rejecting a run
• Must then evaluate the 1 3S rule

8
12S Rule A warning to trigger careful
inspection of the control data
3SD
2SD
12S rule violation
1SD
Mean
-1SD
-2SD
-3SD
Day
9
Westgard 1 3s Rule

• If either of the two control results falls
  outside of 3SD, rule is violated
• Run must be rejected
• If 1 3s not violated, check 2 2s

10
13S Rule Reject the run when a single control
measurement exceeds the 3SD or -3SD control limit
3SD
2SD
1SD
13S rule violation
Mean
-1SD
-2SD
-3SD
Day
11
Westgard 2 2s Rule

• 2 consecutive control values for the same level
  fall outside of 2SD in the same direction, or
• Both controls in the same run exceed 2SD
• Patient results cannot be reported
• Requires corrective action

12
22S Rule Reject the run when 2 consecutive
control measurements exceed the same 2SD or
-2SD control limit
3SD
2SD
1SD
22S rule violation
Mean
-1SD
-2SD
-3SD
Day
13
Westgard R-4s Rule

• One control exceeds the mean by 2SD, and the
  other control exceeds the mean by 2SD
• The range between the two results will therefore
  exceed 4 SD
• Random error has occurred, test run must be
  rejected

14
R4S Rule Reject the run when 1 control
measurement exceed the 2SD and the other exceeds
the -2SD control limit
3SD
2SD
1SD
R4S rule violation
Mean
-1SD
-2SD
-3SD
Day
15
Westgard 4 1s Rule

• Requires control data from previous runs
• Four consecutive QC results for one level of
  control are outside 1SD, or
• Both levels of control have consecutive results
  that are outside 1SD

16
(No Transcript)
17
Westgard 10X Rule

• Requires control data from previous runs
• Ten consecutive QC results for one level of
  control are on one side of the mean, or
• Both levels of control have five consecutive
  results that are on the same side of the mean

18
10x Rule Reject the run when 10 consecutive
control measurements fall on one side of the mean
3SD
2SD
1SD
Mean
10x rule violation
-1SD
-2SD
-3SD
Day
19
What to do when Control Value is out of limit?

• out of control
• Stop testing
• Identify and correct problem
• Repeat testing on patient samples and controls
• Do not report patient results until problem is
  solved and controls indicate proper performance

20
Analysis of QC Data Over Time

• Levey-Jennings control charts
• -Gives information about precision, accuracy
• -Ideally have control values clustered about the
  mean with little variation in the upward or
  downward direction
• Need to review and document

21
Findings Over Time

• Imprecision large amount of scatter about the
  mean. Usually caused by errors in technique
• Inaccuracy may see as a trend or a shift,
  usually caused by change in the testing process,
  deterioration of reagents etc.
• Random error no pattern. Usually poor
  technique, malfunctioning equipment

22
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
23
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
24
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
25
1 2s Rule Warning
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
26
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
27
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
28
Urea mg/ dl
Level 1
1 3s Rule Reject Run
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
29
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
30
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
31
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
32
Urea mg/ dl
Level 1
1 2s Rule Warning
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
33
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
34
Urea mg/ dl
Level 1
2 2s Rule Reject Run
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
35
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
36
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
37
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
38
Urea mg/ dl
Level 1
2 2s Rule Reject Run
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
39
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
40
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
41
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
42
Urea mg/ dl
Level 1
R-4s Rule Reject Run
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
43
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
44
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
45
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
46
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
47
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
48
Urea mg/ dl
Level 1
4 1s Rule Reject Run
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
49
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
50
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
51
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
52
Urea mg/ dl
Level 1
4 1s Rule Reject Run
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
53
Urea mg/ dl
Level 1
3SD 36.98
2SD 35.32
1SD 33.66
Mean 32.00
-1SD 30.34
-2SD 28.68
-3SD 27.02
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
Level 2
3SD 54.56
2SD 53.04
1SD 51.52
Mean 50.00
-1SD 48.48
-2SD 46.96
-3SD 45.44
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
16 17 18 19 20 21 22 23 24 25
54
Westgard Multirule QC