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Good laboratory practices

with waived test systemsJanuary 2002

Washington State Department of HealthOffice of Laboratory Quality Assurance (206) 418-5600 www.doh.wa.gov/lqa.htm

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What is a “waived” test?

• Under CLIA, tests are categorized by complexity– Waived, PPMP, Moderate, High

• Waived tests are:– Simple lab examinations or procedures– Cleared by FDA for home use– Negligible likelihood of erroneous results– No reasonable risk of harm if performed incorrectly

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What does “waived” mean?

• Waived from most requirements established for tests of higher complexity– Site inspections are not routinely performed– Proficiency testing is not required– Personnel qualifications are not established

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What do the Washington State regulations say for waived testing?

• Obtain a Medical Test Site license• Tell us which waived tests you perform• Follow manufacturer’s instructions for

performance of the test

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Waived tests are simple, but …

• Any test can produce erroneous results if not performed properly

• Any test worth running should be associated with good laboratory practices

• What are good laboratory practices?• What are good risk management practices?

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Have a current product insert

• Make sure it states “CLIA waived”– For some tests (defined in regulations) – all are

waived (i.e., fecal occult blood)– For some tests – only certain specific test systems

are waived (i.e., Strep antigen)– For some test kits – test may be waived or moderate

complexity, depending on specimen used (i.e., mononucleosis – whole blood is waived, serum or plasma is moderate complexity

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Focus on these sections

• Intended use• Product storage• Precautions/Warnings• Patient preparation• Specimen collection • Test procedure

• Procedural notes• Quality control• Results/Interpretation• Limitations • Expected results

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• In the following slides, we give examples (in quotations) from actual product inserts to show the kinds of information you will find in the various sections of the product insert

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Intended use

• Describes what is actually being measured– “measures percent concentration of HgbA1C in

blood”• Qualitative versus quantitative

– “qualitative detection of Group A Strep antigen directly from throat swab”

• Type of specimen– “not recommended for use with gastric specimens”

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Product storage

Kits, reagents, test devices– “store refrigerated at 2 – 8 degrees C” – “keep 3 months at room temperature”– “cassettes must be stored in sealed foil pouches”– “store out of sunlight”– “strips must be kept in bottle with cap tightly closed”

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Precautions / Warnings

• Proper handling of kits, reagents, test devices– “do not use past expiration”– “do not mix components of different lots or kits”– “should not be interpreted by individuals with blue

color deficiency (color blindness)”– “do not interchange caps on reagents”

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Patient preparation

• Examples:– CLO test

• “discontinue use of antibiotics and bismuth preparations 3 weeks before biopsy”

– Occult blood• “for 7 days … avoid non-steroidal anti-inflammatory drugs,

for 3 days … avoid vitamin C in excess of 250 mg a day, … avoid red meats …”

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Specimen collection, handling

• Acceptable types of specimens– “finger stick or venipuncture”– “can be stored at room temperature for 4 hours and

up to 72 hours if refrigerated”– “do not use swabs that have cotton tips or wooden

shafts”• Acceptable anticoagulants

– “acceptable anticoagulants are EDTA, heparin, citrate, fluoride”

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Test procedure/Directions/Instructions

• Follow exactly • Don’t modify• Adhere to timing

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Procedural notes

• “do not open foil pouch until ready to test … avoid cross contamination … read results within 20 minutes”

• “directions must be followed exactly, accurate timing is essential”

• “allow specimen and test devices to warm to room temperature before use”

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Quality control

• The types of controls to be tested vary with the specific test system used– External, Internal, Electronic

• Test controls according to the manufacturer’s instructions– Read the entire Quality Control section carefully

• Assure that you get the expected results for the controls tested

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Quality control

• External controls– Reference solutions or materials (i.e., swabs)– Added to test device like the patient sample– May be included with the test kit or you may need to

purchase separately– Compare your control results to the expected ranges

or values printed on the control vials or in the control product insert

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Quality control

• Internal (built-in, procedural) controls– Built into test reagent devices to ensure that

reagents are active, reagents & samples are added correctly, test performs according to specifications

– Common with qualitative tests • (Strep antigen, pregnancy, H. pylori, mononucleosis)

– Procedural controls typically include the appearance of a colored dot, line or bar in a control region and/or an expected appearance of the device background

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Quality control

• Electronic controls– Inert, reusable devices

• (test strips, cartridges, cassettes) – Used to check instrument performance specifications– Available for use with some quantitative test systems

• (hemoglobin, cholesterol, A1C, prothrombin time)

– Compare the control results with the expected values

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Results / Interpretation

• Positive• Negative • Invalid• Reportable range of method

– “patient values are linear from 2.5% to 14.0%”– “linear up to 23.5 g/dl”

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Limitations of procedure

• Causes of false positives, false negatives• “patients must have a total hemoglobin between

7 and 24 g/dl”• “measuring range is 100 to 500”

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Expected results, values

• “the following values are considered normal…”• “normal range is 4.3% - 5.7%”• “95% of prothrombin time values range from

10.6 to 13.4 seconds”• “for the purposes of calculating the INR, normal

is defined as 12.0 seconds”• “will detect 20 mIU/ml of HCG”

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Good laboratory practices

• Test controls - Follow manufacturer instructions – “positive and negative controls should be tested with each

new lot or shipment of test materials”– “Daily Requirements: Two levels of electronic quality control

or two levels of liquid controls must be tested…”– “a positive and negative control must be tested when opening

a new test kit and with each change in operator within the test kit”

– “check the calibration daily by using the control cuvette”

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Good laboratory practices

• At minimum, test external controls with each new lot of kits, reagents, testing devices– To detect problems during shipment

• Observe internal (built-in, procedural) controls with each patient test– To assure proper test performance, reagent integrity

• Test electronic controls periodically– According to manufacturer’s instructions & frequency

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Good laboratory practices

• Correlate test results with patient presentation, history, diagnosis

• Participate in a proficiency testing (PT) program– Many PT companies offer 2 sample programs

• Split sample program– Compare your results with reference laboratory

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Training

• Have new employees read the entire product insert– Not just the Quick Reference Card

• Keep a record of training• Have each employee demonstrate competency

– Initially– Periodically

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Keep a simple log of results

• By keeping results of the following in chronological order, you can detect potential problems:– New lots of reagents, kits, testing devices– Quality control results– Patient test results

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Report test system problems

• To manufacturer• To Food & Drug Administration’s MedWatch

– Call 1-800-FDA-1088

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Questions?

• Call the Office of Lab Quality Assurance:– (206) 418-5600

• Go to our website:– www.doh.wa.gov/lqa.htm