Principles of Internal Quality and External Quality Assurance

1. 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

2. 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: • Setting standards of performance & designating responsibility • Ensuring definitive corrective actions are taken when the criteria not met • Performing measurements within a stated level of confidence

3. Quality Control (QC) • A quality control system is an indicator system for documented performance and actions that: • Provides a record of consistency of performance • Records action taken when performance fails to meet standard • Thus quality control is tool by which the principle of quality assurance is achieved.

4. 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.

5. 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.

6. 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.

7. 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.

8. Levy Jenning Plot + SD Mean - SD 50 Day of Month P P M of I2 40 30 20 10 0 Levy Jenning Plot

9. Levy Jenning Plot

10. 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.

11. 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.

12. 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.

13. 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.

14. Thank You “Quality assurance is not a fault finding mission but a method to ensure quality of results from each laboratory.”