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# Levey jenning control charts

## on Oct 24, 2013

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Control Charts - Courtesy FICCI

Control Charts - Courtesy FICCI

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## Levey jenning control chartsPresentation Transcript

• LEVEY - JENNINGS CONTROL CHARTS FICCI QUALITY FORUM 1 Training on assuring quality of test results
• THE LEVEY-JENNINGS CONTROL CHART Dr. W.A. Shewhart invented the control chart in 1924 A Levey-Jennings chart is a graph on which quality control data is plotted to give a visual indication whether a laboratory test is working well. The Levey-Jennings Chart displays information about the quality control samples performed on laboratory analytes FICCI QUALITY FORUM 2 Training on assuring quality of test results
• THE LEVEY-JENNINGS CONTROL CHART METHODOLOGY i) ii) select appropriate control materials analyze those materials to characterize method performance by collecting at least 20 data points iii) calculate the mean and standard deviation of those data iv) select the number of control measurements to be used per run FICCI QUALITY FORUM 3 Training on assuring quality of test results
• EXAMPLE - 1 Let the Control Material be a cholesterol sample of 200 mg/dL. This control is tested everyday for 25 days and the data generated are : 198, 197, 201, 204, 200, 201, 199, 197, 197, 199, 200, 203, 199, 198, 197, 196, 196, 199, 196, 202, 201, 198, 203, 201, 199 mg/dL = 199.24 mg/dL 199 mg/dL = 2.31 mg/dL 3 Control Limit = 3 = 192 to 206 mg/dL 2 Control Limit = 2 = 194 to 204 mg/dL FICCI QUALITY FORUM 4 Training on assuring quality of test results
• LEVEY-JENNINGS CHART m g +3 = 206 mg/dL / +2 = 204 mg/dL d L Average = 199 mg/dL -2 = 194 mg/dL -3 = 192 mg/dL DAYS FICCI QUALITY FORUM 5 Training on assuring quality of test results
• The laboratory shall run a minimum of one level QC (1 in every 20 samples tested) at least once a day Where samples (parameter) exceed 20 a day, two level QC to be employed at least once a day for such parameters Typically, QC should be around 5% of samples tested FICCI QUALITY FORUM 6 Training on assuring quality of test results
• Rule for 1 level QC Reject QC if: a) It is outside 3 SD (13s) b) two consecutive values obtained outside 2 SD on the same side within 3 SD (22s) c) ten consecutive values are above below the mean, but within 2 (10x) FICCI QUALITY FORUM 7 are but or SD Training on assuring quality of test results
• CASE - 1 The value of the Control tested for a period 11 days gave the following data : Day Day Day 1 2 3 Day 4 Day 5 Day 6 Day Day Day Day Day 7 8 9 10 11 202 198 195 196 200 204 FICCI QUALITY FORUM 207 8 202 201 197 199 Training on assuring quality of test results
• LEVEY-JENNINGS CHART - 1 m g +3 = 206 mg/dL / +2 = 204 mg/dL d L Average = 199 mg/dL -2 = 194 mg/dL -3 = 192 mg/dL DAYS FICCI QUALITY FORUM 9 Training on assuring quality of test results
• CASE - 2 The value of the Control tested for a period 11 days gave the following data : Day Day Day 1 2 3 Day 4 Day 5 Day 6 Day Day Day Day Day 7 8 9 10 11 202 198 195 196 200 205 FICCI QUALITY FORUM 205 10 202 201 197 199 Training on assuring quality of test results
• LEVEY-JENNINGS CHART - 2 m g +3 = 206 mg/dL / +2 = 204 mg/dL d L Average = 199 mg/dL -2 = 195 mg/dL -3 = 192 mg/dL FICCI QUALITY FORUM 11 DAYS Training on assuring quality of test results
• CASE - 3 The value of the Control tested for a period 11 days gave the following data : Day 1 Day Day 2 3 Day 4 Day 5 Day 6 Day 7 Day Day Day 8 9 10 Day 11 201 204 200 200 203 200 202 199 FICCI QUALITY FORUM 203 12 201 203 Training on assuring quality of test results
• LEVEY-JENNINGS CHART - 3 m g +3 = 206 mg/dL / +2 = 204 mg/dL d L Average = 199 mg/dL -2 = 195 mg/dL -3 = 192 mg/dL FICCI QUALITY FORUM 13 DAYS Training on assuring quality of test results
• CASE - 4 The value of the Control tested for a period 11 days gave the following data : Day Day Day 1 2 3 Day 4 Day 5 Day 6 Day Day Day Day Day 7 8 9 10 11 202 198 195 196 200 204 FICCI QUALITY FORUM 197 14 202 201 197 199 Training on assuring quality of test results
• LEVEY-JENNINGS CHART - 4 m g +3 = 206 mg/dL / +2 = 204 mg/dL d L Average = 199 mg/dL -2 = 195 mg/dL -3 = 192 mg/dL FICCI QUALITY FORUM 15 DAYS Training on assuring quality of test results
• EXERCISE - 6 Data generated from testing of the reference material are : 2.24, 2.29, 2.27, 2.19, 2.11, 2.13, 2.44, 2.33, 2.12, 2.13, 2.38, 2.28, 2.36, 2.34, 2.41, 2.22, 2.47, 2.18, 2.31, 2.36, 2.21, 2.20, 2.25, 2.42. Prepare a Levy-Jennings chart from the above data FICCI QUALITY FORUM
• EXERCISE - 7 Subsequent data generated from the reference material for the next 11 days are : Day Day Day Day Day Day Day Day Day Day Day 1 2 3 4 5 6 7 8 9 10 11 2.14 2.61 2.43 2.09 2.51 2.23 2.39 2.16 2.13 2.62 2.34 Check whether the daily controls are within acceptable limits FICCI QUALITY FORUM
• EXAMPLE - 2 2-Level Quality Control Material (QC) is used for analysis of Blood Glucose covering the low range and the normal range. The value of the QCS are : Low level - 50 to 60 mg/dL Normal level - 90 to 110 mg/dL These two controls are tested everyday for 25 days and the data generated together with the data analysis are stated on the following slides. FICCI QUALITY FORUM
• EXAMPLE - 2 (Contd) Low level - 50 to 60 mg/dL 58, 56, 58, 55, 55, 59, 63, 60, 57, 54, 56, 63, 64, 62, 63, 59, 58, 62, 59, 57, 58, 57, 62, 63, 61 mg/dL = 59.2 mg/dL 59 mg/dL = 3 mg/dL 3 Control Limit = 3 = 50 to 68 mg/dL 2 Control Limit = 2 = 53 to 65 mg/dL FICCI QUALITY FORUM
• EXAMPLE - 2 (Contd) Normal level - 90 to 110 mg/dL 94, 96, 93, 98, 105, 106, 109, 104, 105, 107, 106, 99, 98, 99, 102, 103, 106, 92, 97, 103, 109, 110, 99, 105, 94 mg/dL = 102 mg/dL = 5 mg/dL 3 Control Limit = 3 = 86 to 118 mg/dL 2 Control Limit = 2 = 91 to 113 mg/dL FICCI QUALITY FORUM
• Rule for 2 level QC Reject QC if: a) either QC values is outside 3 SD (13s) b) both QC values are outside 2 SD on the same side, but within 3 SD (22s) c) difference between both QC values is > 4 SD i.e. one level QC is > 2 SD and other level QC is < 2 SD (R4s) d) 10 consecutive values of the same level QC are above or below the mean, but within 2 SD (10x) e) 5 consecutive values of one same level QC and 5 consecutive values of the other level QC are above or below the mean, but within 2 SD (10x) FICCI QUALITY FORUM
• EXAMPLE OF ACCEPTABLE QC The value of the Controls tested for a period 11 days gave the following data : LOW LEVEL Day Day Day Day Day Day Day Day Day Day Day 1 2 3 4 5 6 7 8 9 10 11 52 57 61 63 60 59 53 64 59 66 65 NORMAL LEVEL Day Day Day Day Day Day Day Day Day Day Day 1 2 3 4 5 6 7 8 9 10 11 99 104 111 95 FICCI QUALITY FORUM 107 97 96 93 105 98 90
• +3 =118 mg/dL +2 =113 mg/dL Average=102 mg/dL -2 = 91 mg/dL -3 = 86 mg/dL +3 = 68 mg/dL +2 = 65 mg/dL Average = 59 mg/dL -2 = 53 mg/dL -3 = 50 mg/dL FICCI QUALITY FORUM
• CASE - A The value of the Controls tested for a period 11 days gave the following data : LOW LEVEL Day Day Day Day Day Day Day Day Day Day Day 1 2 3 4 5 6 7 8 9 10 11 52 62 61 60 63 64 58 64 59 66 70 NORMAL LEVEL Day Day Day Day Day Day Day Day Day Day Day 1 2 3 4 5 6 7 8 9 10 11 99 107 110 98 FICCI QUALITY FORUM 109 97 99 97 102 98 100
• +3 =118 mg/dL +2 =113 mg/dL Average=102 mg/dL Normal QC -2 = 91 mg/dL -3 = 86 mg/dL Low Level QC +3 = 68 mg/dL +2 = 65 mg/dL Average = 59 mg/dL -2 = 53 mg/dL -3 = 50 mg/dL Reject since on Day 11, Low Level QC value exceeds 3 FICCI QUALITY FORUM (13s)
• CASE - B The value of the Controls tested for a period 11 days gave the following data : LOW LEVEL Day Day Day Day Day Day Day Day Day Day Day 1 2 3 4 5 6 7 8 9 10 11 55 63 60 57 64 62 58 64 52 64 67 NORMAL LEVEL Day Day Day Day Day Day Day Day Day Day Day 1 2 3 4 5 6 7 8 9 10 11 97 105 111 99 FICCI QUALITY FORUM 107 96 100 101 93 98 115
• +3 =118 mg/dL +2 =113 mg/dL Average=102 mg/dL Normal QC -2 = 91 mg/dL -3 = 86 mg/dL Low Level QC +3 = 68 mg/dL +2 = 65 mg/dL Average = 59 mg/dL -2 = 53 mg/dL -3 = 50 mg/dL Reject since on Day 11, both QC values are between 2 & 3 on the same side (22s) FICCI QUALITY FORUM
• CASE - C The value of the Controls tested for a period 11 days gave the following data : LOW LEVEL Day Day Day Day Day Day Day Day Day Day Day 1 2 3 4 5 6 7 8 9 10 11 55 64 61 58 67 60 57 61 59 66 63 NORMAL LEVEL Day Day Day Day Day Day Day Day Day Day Day 1 2 3 4 5 6 7 8 9 10 11 99 107 110 98 FICCI QUALITY FORUM 89 99 108 104 96 92 105
• CASE – C (contd) LOW LEVEL Day Day Day Day Day Day Day Day Day Day Day 1 2 3 4 5 6 7 8 9 10 11 55 64 61 58 67 60 57 61 59 66 63 NORMAL LEVEL Day Day Day Day Day Day Day Day Day Day Day 1 2 3 4 5 6 7 8 9 10 11 99 107 110 98 Day – 5, 2.67 FICCI QUALITY FORUM 89 99 108 104 96 67 = 2.67 - (- 2.6 ) = 5.27 89 = - 2.6 and thus > 4 92 105
• +3 =118 mg/dL +2 =113 mg/dL Average=102 mg/dL -2 = 91 mg/dL -3 = 86 mg/dL Normal QC Low Level QC +3 = 68 mg/dL +2 = 65 mg/dL Average = 59 mg/dL -2 = 53 mg/dL -3 = 50 mg/dL Reject since difference between 1 & 2 level QC values on Day 5 is > 4 (R4s) FICCI QUALITY FORUM
• CASE - D The value of the Controls tested for a period 11 days gave the following data : LOW LEVEL Day Day Day Day Day Day Day Day Day Day Day 1 2 3 4 5 6 7 8 9 10 11 55 64 61 58 67 60 57 61 59 63 66 NORMAL LEVEL Day Day Day Day Day Day Day Day Day Day Day 1 2 3 4 5 6 7 8 9 10 11 99 98 FICCI QUALITY FORUM 95 101 97 99 100 97 101 98 104
• +3 =118 mg/dL +2 =113 mg/dL = 102 mg/dL Normal QC Low Level QC -2 = 91 mg/dL -3 = 86 mg/dL +3 = 68 mg/dL +2 = 65 mg/dL = 59 mg/dL -2 = 53 mg/dL -3 = 50 mg/dL Reject since 10 consecutive values of level 2 QC, are on the same side of mean (10x) FICCI QUALITY FORUM
• CASE - E The value of the Controls tested for a period 11 days gave the following data : LOW LEVEL Day Day Day Day Day Day Day Day Day Day Day 1 2 3 4 5 6 7 8 9 10 11 63 64 61 62 64 58 57 61 59 63 56 NORMAL LEVEL Day Day Day Day Day Day Day Day Day Day Day 1 2 3 4 5 6 7 8 9 10 11 107 98 111 105 104 112 100 97 101 98 100 FICCI QUALITY FORUM
• +3 =118 mg/dL +2 =113 mg/dL = 102 mg/dL Normal QC -2 = 91 mg/dL -3 = 86 mg/dL Low Level QC +3 = 68 mg/dL +2 = 65 mg/dL = 59 mg/dL -2 = 53 mg/dL -3 = 50 mg/dL Reject since 5 consecutive values each of both QC levels are on the same side of mean (10x) FICCI QUALITY FORUM
• Three types of change is commonly observed in LJ Plots, which results from different sources: 1. 2. 3. FICCI QUALITY FORUM Drift or Trend Dispersion Shift
• DRIFT Seen when the control value moves progressively in one direction from the mean for a minimum of three (3) days Suggests that a problem is gradually developing, such as deterioration of a reagent or control FICCI QUALITY FORUM
• DISPERSION Increase in Random Errors and Lack of Precision Suggests inconsistency technique or fluctuations instrumentation function FICCI QUALITY FORUM of in
• SHIFT Abrupt changes observed when a problem develops suddenly May be due malfunction or technique FICCI QUALITY FORUM to an instrument error in