LEVEY JENNINGS CONTROL CHART AND WESTGARD RULES

Quality Control

process to periodically examine a measurement procedure to verify that it is performing according to pre-established specifications

patient results are not reported and corrective actions is necessary

If QC results are not within acceptable limits, therefore

patient samples can be reported and are suitable for clinical use

If result for a QC material is within acceptable limits

Levey-Jennings (Shewhart)

developed by Levey and Jennings in 1950

Levey-Jennings (Shewhart)

most common presentation for evaluating QC results

Levey-Jennings (Shewhart)

shows each QC result SEQUENTIALLY over time and allows a quick visual assessment of method performance, including trend detection

1_{2S rule}

one observation exceeds 2 SD from target value

1_{2S rule and} 10_{x rule}

not recommended because it has excessive false alert rate

1_{3S rule}

one observation exceeds 3 SD from the target value

2_{2S rule}

two sequential observations exceeds 2 SD ( or 2.5) from target value in SAME direction

R_{4S rule}

range between two observations in the same run exceeds 4 SD

10_{x rule}

Ten sequential observations for the same QC sample are on the SAME side of target value

4_{1S rule}

Four sequential observations for the same QC sample exceeds 1 SD ( or 1.5) in the SAME direction from target value