# Presentation: 272518

## Module 12: Quality Control

## The Lab Quality System

## Learning Objectives

- At the end of this module, you will be able to:
- Differentiate between internal and external controls
- Use external quality controls at designated frequencies
- Analyze common problems associated with invalid test results

## Content Overview

- What is Quality Control (QC)?
- Benefits of QC in rapid testing
- Internal versus external quality control
- Troubleshooting invalid results
- Quality control records

## What Is Quality Control (QC)?

- Measures taken to monitor the quality of the test itself
- QC for HIV Rapid Testing includes:
- Testing of samples with known results to verify if the procedure is working properly
- Interpreting the presence or absence of control bands/lines within the device itself
- If an error occurs, do not release or report results until you have corrected the error.

## Sources of Controls

- Internal to the test Kit
- Control samples provided with the test kit with known reactivity
- Region within the device, also termed procedural or in-built control
- External to the test Kit
- Control samples not included with the test kit provided an external source that has been validated for use with a specific test kit

## Internal and External Quality Control

_**Internal Control **_
- Included in testing device or as part of the kit

_**External Control**_
- Known positive and negative samples that are used to validate the reliability of the test system

## Examples of Tests that Include Internal Control

- Capillus
- Determine
- Hema-Strip
- OraQuick
- Uni-Gold

**Which test does not have internal control built into its device?**

## Capillus Kit Comes with Internal  Control Samples

**Positive and Negative**
**Control Samples**

## Sources of External Quality Control Samples

**Commercially prepared**

**Prepared by Reference Laboratory**

- Store according to instructions
- Date when opened
- Use before expiry date
- Do not contaminate

## Frequency of Use:  When Should You Test External Control Samples?

- Minimum once a week, beginning of the week
- New shipment of test kits
- Beginning a new lot number
- Environmental conditions exceed range needed for stability of kits

## Invalid Results – What Do You Do? 

- Repeat test
- If repeatedly invalid:
- assume problem with test product or procedure
- continue with alternative testing algorithm
- Identify cause of problem
- Inform supervisor
- Take corrective actions

## Troubleshooting Invalid Results

- No control line or band present

**Problem**

**Potential Cause**

**Action**

- Damaged test device or controls

- Repeat the test using new device and blood sample

- Proper procedure not followed

- Follow each step of testing according to SOP
- Re-check buffer and/or specimen volumes
- Wait for the specified time before reading the test

- Expired or improperly stored test kits or controls

- Check expiration date of kits or controls.  Do not use beyond stated expiration date

- Check temperature records for storage and testing area

## Troubleshooting Invalid Results – Cont’d

- Positive reaction with negative external control, i.e. false positive

**Problem**

**Potential Cause**

**Action**

- Incubation time exceeded

- Re-test negative control using a new device and read results within specified time limit

- Extremely faint control line

- The control line
- can vary in intensity

- No action required.  Any visible line validates the results.

## Possible HIV Test Outcomes:  Parallel Algorithm

| TEST 1 | TEST 2 | TEST 3 | HIV Status |
| --- | --- | --- | --- |
| Non-reactive | Non-reactive |  | Negative |
| Reactive | Reactive |  | Positive |
| Non-reactive | Reactive | Non-reactive | Negative |
| Reactive | Non-reactive | Non-reactive | Negative |
| Non-reactive | Reactive | Reactive | Positive |
| Reactive | Non-reactive | Reactive | Positive |

**Notes:**
Invalid test needs to be repeated 
Does not count toward outcome of test

## Exercise #1: Interpreting Rapid Test Results

- Refer to the handout in your participant manual
- Read the test results and write your interpretation in the space provided.
- Time: 3 minutes

## Exercise #2: Resolving Unreportable Test Results

**Uni-gold****	**

**Determine**

**Hema-strip**

**Notes:**
No external control materials were available to the testing site
Tester received discordant test results from Screening test (Unigold) and Confirmatory test (Determine).  The algorithm called for conducting a third test or tiebreaker to determine HIV status of patient. 
Pass around an invalid test result. 

Pose questions to participants –
What are the individual test results?
Proceed to next slide with additional questions.

## Exercise #2: Resolving Un-reportableTest Results – Cont’d

- Should you accept the results?
-  If not,
- What should be your next steps?
- What might have caused the tiebreaker test to yield an invalid result?
- What corrective actions might you take?

## Maintaining Quality Control Records

_**WHY?**_
- Trouble-shooting
- Provides proof reliable test results

_**WHEN?**_
- Each time QC materials are tested
- Record all invalid results and inform supervisor

_**HOW?**_
- Use standard worksheets

## Quality Control Record: An Example

**Quality Control Record: An Example**

## Periodic Review of Records

- Review of internal control results before accepting test results
- Review of external control results by test performer
- Weekly or monthly review of external quality control results by testing site supervisor
- Periodic audits or assessments

## Summary

- What is quality control?
- What is an internal quality control?
- What is an external quality control?
- How often and when should external controls be used?

## Summary – Cont’d

- What would you do if your external control tested invalid?
- Give examples of problems encountered with QC results, why they occurred, and how to correct them.
- Why is it important to maintain records of QC results?