Requirements

for good

laboratory

practice

and COLA

Laboratory

Accreditation

programs

are underlined.

© COLA--revised 5/99. COLA LabFacts® is a registered trademark of COLA.

8-1

LABFACTS 8

INTRODUCTION

Proficiency testing (PT) is an important aspect of anoverall quality assurance program. PT serves as anexternal check to verify the accuracy of a laboratory'sresults by providing specimens with unknownvalues.

Labs run the PT specimens in the same manner as apatient specimen and report the results to the profi-ciency testing program. When all of the results arereceived by the proficiency testing program, they aregrouped, analyzed, and then reported back to theparticipating laboratories.

PT specimen kits are designed to provide a suitablechallenge for the testing personnel in the laboratory.Specimen kits are supplied to the participant labora-tory with information and instruction sheets, and anattestation test result form. Participants will receivePT specimens for each specialty three times a year.Shipping schedules for PT specimens are availablefrom your PT program. Be sure to note your program'sshipping dates. If your specimens do not arrive in atimely manner, contact your provider.

TYPES OF SPECIMENS

Types of specimens provided by PT programs mayinclude:

• Liquid specimens such as urine, plasma, serum,whole blood, and other body fluids.

• Dry loop specimens which are provided for bacte-riological identification.

• Lyophilized (freeze-dried) specimens such as urine,plasma, serum, or dried whole blood which requirereconstitution. Solutions to be used during recon-stitution may be provided.

• 35 mm color transparencies which simulate micro-scopic specimens.

PREPARATION

It is important to follow the exact step-by-step instruc-tions for the preparation and analysis of the PTspecimen. The accuracy of your laboratory's PT re-sults is dependent upon both your instrument and PTspecimen reconstitution techniques. Use pipettes of

certified accuracy to reconstitute specimens. ClassA volumetric pipettes for the reconstitution of PTspecimens are available through some PT programsor may be purchased through your laboratory supplydistributor. Pipette pumps used to draw up and dis-pense reconstitution diluents are also available. Referto your PT program manual for information on pi-pettes. Syringes are not acceptable for reconstitu-tion. The hypodermic syringe is not designed for usein the laboratory and is not accurate enough fordispensing, reconstituting, or diluting PT specimens.

DEFINITIONS

Proficiency testing programs use several differentmechanisms to determine the range of acceptableanswers. Here are some definitions of the differentconcepts used in the analyses of the proficiencytesting data:

1. MEAN: The average of all the results. It is calcu-lated by adding together all of the received resultsand dividing the total by the number of participantswho submitted results.

2. STANDARD DEVIATION (SD): A measure ofhow far the result is from the mean. It is a way ofdetermining how much variation there is in theresults. The smaller the SD, the more precise theresults.

3. ACCURACY: The extent to which a test result isclose to the true value of the quantity being mea-sured.

4. PRECISION: The reproducibility of a test result inthe measurement of an analyte. This occurs whenthe repeated analysis of an analyte produces testresults which approximate one another, but maydeviate from the true value.

5. RELIABILITY: A test method’s capacity to main-tain both accuracy and precision.

6. COEFFICIENT OF VARIATION (CV): The con-version of the standard deviation into a percent-age. It is a measure of precision that is used tocompare the amount of error or variation of two ormore different sets of results. Good laboratoriesare able to produce CVs of 5 to 10 percent for mostanalytes. The smaller the CV, the more precise theresults.

Proficiency Testing

Requirements

for good

laboratory

practice

and COLA

Laboratory

Accreditation

programs

are underlined.

© COLA--revised 5/99. COLA LabFacts® is a registered trademark of COLA.

8-2

LABFACTS 8

Along with Proficiency Testing Reports, each par-ticipant laboratory receives Participant SummaryReports which list results from all participants foreach analyte grouped by the methodology used.By comparing the CVs of different instrumentsfrom the Participant Summary Reports, it can bedetermined which instruments provide the mostprecise results.

7. PEER GROUPS: The participants’ results arecombined into groups of laboratories using com-parable methods or instruments called “peergroups.” When the peer group is large enough, theresults obtained from a participant are evaluatedagainst results obtained by the peer group. Whenthe number of participants using a particular in-strument or method is below a cut-off level estab-lished by the PT provider, or when a method notlisted on the PT program answer sheet is reported,the participant is put into a similar group or isevaluated by a comparative method.

8. COMPARATIVE METHOD: A good average oracceptable method that is considered widely com-patible with most current methods. It is used tocompare the various peer groups with a goodhistorically acceptable method. It is also used asthe target value for evaluation of some chemistryanalytes and for evaluating participant results forthose methods designated by insufficient num-bers of participants to generate a separate peergroup. If no comparative method has been desig-nated, results will not be evaluated.

9. FIXED LIMITS: Used for evaluation of quantitativedata. A mean value and SD are calculated for thepeer group. Acceptable performance is estab-lished based on the target value +/- fixed limits.The target values are determined from either thepeer group or comparative method mean.

ENROLLMENT REQUIREMENTS

CLIA regulations and COLA policy state that labora-tories must enroll in PT for all regulated analytes andmust authorize that their PT results be forwarded totheir accrediting agency and/or HCFA (whichever isapplicable). Laboratories must also enroll in PT orperform split-sampling (see LabFacts #9) as anexternal validation of all non-regulated analytes. Pro-ficiency testing for those tests or analytes consideredto be waived by federal regulation is highly recom-mended but not required.

For those regulated analytes which fall under thespecialty of Bacteriology, proper enrollment requiresa minimum of five challenges per subspecialty foreach event. Select modules which offer appropriatechallenges for the methods/procedures performed inyour laboratory (i.e., gram stain, antigen detection,bacterial identification, susceptibility testing).

CLIA regulations and COLA policy state that labora-tories are prohibited from communicating with an-other laboratory to discuss PT results prior to thecutoff date for submission of test results.

CRITERIA FOR SATISFACTORYPROFICIENCY TEST PERFORMANCE

The criteria used by PT providers to score PT resultss definied by HCFA in the Federal Register. Thefollowing definitions are provided to help you interpretyour laboratory's PT performance:

1. Regulated Analyte: Those analytes designatedby the Federal Government which require PTenrollment. Refer to the Regulated Analyte listincluded at the end of this LabGuide.

2. Testing Event: The time period during which thelaboratory receives their PT kit, performs thetesting, and returns their results to the PT pro-vider. There are three events, evenly spacedthroughout the calendar year, in which the labora-tory must participate.

3. Challenge: The actual sample provided for PTtesting. A minimum of five challenges per testevent are required for each regulated analyte.

4. Unsatisfactory: A failure to achieve a minimumsatisfactory score for an analyte, specialty, orsubspecialty for a single test event.

5. Unsuccessful: A failure to achieve a minimumsatisfactory score for an analyte, specialty, orsubspecialty for two consecutive or two of threetest events.

6. Consecutive Unsuccessful: Unsuccessful PTperformance followed by unsatisfactory perfor-mance in either of the next two testing eventsfollowing the initial unsuccessful performance.

Requirements

for good

laboratory

practice

and COLA

Laboratory

Accreditation

programs

are underlined.

© COLA--revised 5/99. COLA LabFacts® is a registered trademark of COLA.

8-3

LABFACTS 8

7. Reinstatement of an Analyte: The correctiveactionprocess followed to demonstrate that a laboratoryis prepared to successfully begin retesting ananalyte, specialty, or subspecialty following aperiod of cease testing.

A minimum overall testing event score of 80 percentfor each regulated analyte, specialty, and subspe-cialty, except for ABO/Rh which has a minimumscore of 100 percent for each testing event, must beachieved for satisfactory PT performance.

TROUBLESHOOTING

Keep in mind that unsuccessful PT performance maybe an indication of problems with instrumentation,personnel training, or quality control procedures. It isa good idea to retain and freeze remaining PTsamples, except for whole blood, so they may beretested if troubleshooting becomes necessary.Whole blood should be stable refrigerated until re-sults are received.

If your laboratory’s result is outside the range of“acceptable values,” then there is a problem thatmust be identified and corrected. Use the followingquestions as a guide to identifying where the problemlies:

1. What is the scope of this problem?• Is a single or are several analytes affected?• Is a single or are several specimens affected?• Is a single or are several instruments affected?• Are all ranges or just a certain range of test results

affected?

Narrowing the scope of the problem may lead you inthe direction of where corrective action is needed.

2. Can you identify any clerical errors?• Copied onto answer sheet correctly?• Numbers reversed on answer sheet?• Was the proper method code used?• Did the PT program enter your answer correctly?If clerical errors are the cause of the problems,document your findings and take corrective action toavoid these types of errors in the future. If the PTprogram made a mistake, contact them immediatelyto have the error corrected. If this was not the sourceof the problem, continue:

3. Can you identify any technical processing errorsor instrument failures?

• Quality Control acceptable at time of testing event?• Misidentification of specimens?• Specimen preparation error?• Results accepted outside linearity of instrument?• Are calibrations up to date?• Has maintenance been performed appropriately?• Have there been shifts, trends or other changes in

the Quality Control results since the testing event?• Were all reagents, controls, and samples stored

properly and not expired?

If any of these questions identifies a possible prob-lem, take corrective action, document and proceed toverify your corrective actions have worked by usingfrozen PT samples, requesting additional PT samplesor using another form of external validation. Remem-ber to document all corrective action and retain this inyour laboratory’s records.

DOCUMENTATION

It is very important to maintain accurate records of PTdata during each testing event. The following itemshighlight some key points for successful documenta-tion of PT performance.

• Document each step of the handling, preparation,processing, and examination of the PT specimen.

• The individual testing the PT specimen and thelaboratory director must sign an attestation state-ment that PT specimens are tested under thesame conditions as patient specimens.

• The laboratory director should review PT resultson a regular basis with the laboratory staff andaddress any unsuccessful PT events.

• Initial and date the PT data to indicate that theresults have been reviewed.

• Retain all records of proficiency testing participa-tion for two years, except for immunohematologydata which must be retained for five years.

person double check the answer sheet beforesending it to your PT provider.

• Identify the correct instrument or method code soyou are graded among your peer group. If you arenot sure which method code to use, telephoneyour PT program’s Customer Service area forhelp.

• If you do not perform a particular analyte listed onthe answer form, use the correct code to indicatethis (such as Test Not Performed). Answer formsleft blank are often counted as a failure to partici-pate and could reflect negatively on your summaryscore.

• Make and retain copies of all answer forms prior tosubmitting your results to your PT provider.

• Be sure that the attestation form is signed.

• Carefully review all participant summary reports,follow up on reasons for PT failures, and correctthem.

• Document all corrective action in your lab’s records.

• If you cannot perform PT for an analyte(s) nor-mally tested in your laboratory due to circum-stances beyond your control, notify your PT pro-vider in writing. List the analyte(s) affected andgive the reason for lack of performance. Your PTprovider can grant an exclusion if they feel thesituation warrants it. This will result in your labora-tory receiving a passing score for the analyte forthat event rather than a failing score. Note: PTproviders will not grant multiple requests for exclu-sions!

• Notify HCFA and/or your accrediting agency ofany changes to your test menu and the effectivedate.

HELPFUL HINTS FOR PROFICIENCY TESTING

Below are some hints to help you obtain optimalproficiency testing results:

• Enroll in PT for all federally regulated analytes.

• Be sure to indicate to your PT program whichanalytes you do not perform in your laboratory.

• Give your PT provider your CLIA identificationnumber. If you participate with an accreditingorganization, provide the name of the accreditingbody and your ID number. If you have a State IDnumber, give this information as well.

• If your practice has satellite labs, provide theunique CLIA number, and any other ID numberssuch as those listed above, for each physicallocation to your PT provider. This will ensure thatPT results from satellite labs are identified cor-rectly by your PT provider and forwarded correctlyto HCFA, the State, and your provider.

• If you do not receive your PT specimens, refer tothe shipping schedule provided by your PT pro-gram to alert them within the allotted time if ashipment has been missed. They will send areplacement shipment promptly if notified in time.

• Contact the PT program promptly if PT specimensare received damaged. You may be able to re-ceive a replacement.

• Strictly follow the PT providers storage or handlingrequirements prior to testing PT specimens.

• Use a volumetric pipette to reconstitute lyophilizedPT specimens. Syringes are not as accurate as avolumetric pipette, and using a syringe will mark-edly increase your chances of unsatisfactory PTperformance.

• Analyze PT specimens within the time frameprovided by the PT provider; promptly reportresults.

• Avoid clerical errors when completing PT answersheets. Be sure to enter the correct result next tothe correct analyte on the answer form. Institute aquality assurance measure of having another staff

Requirements

for good

laboratory

practice

and COLA

Laboratory

Accreditation

programs

are underlined.

© COLA--revised 5/99. COLA LabFacts® is a registered trademark of COLA.

8-4

LABFACTS 8

Lactate Dehydrogenase (LDH)LDH, IsoenzymeMagnesiumPotassiumSodiumProtein, TotalTriglyceridesUrea Nitrogen (BUN)Uric Acid

Subspecialty: Endocrinology

CortisolFree ThryroxineHuman Chorionic Gonadotropin (hCG)T3 UptakeTriiodothyronine (T3)Thyroid Stimulating Hormone (TSH)Thyroxine (T4)

Subspecialty: Toxicology

Alcohol (Blood)Lead (Blood)CarbamazepineDigoxinEthosuximideGentamicinLithiumPhenobarbitalPrimidoneProcainamideQuinidineTheophyllineVancomycinValproic Acid

SPECIALTY: HEMATOLOGY

Cell ID/ White Blood Cell DifferentialErythrocyte CountHematocrit (excluding spun Microhematocrits)HemoglobinLeukocyte CountPlatelet CountFibrinogenPartial Thromboplastin TimeProthrombin Time

SPECIALTY: IMMUNOHEMATOLOGY

Unexpected Antibody Detection ABO/RHOABO GroupD(RHO) TypingAntibody IdentificationCompatibility Testing

8-5

LABFACTS 8SPECIALTY: MICROBIOLOGY

Subspecialty: Bacteriology All Cultures (including growth/no growth)/ Susceptibility Test-ing/Gram Stain/Antigen Detection/Bacterial Identification.

Subspecialty: MycologyCulture for Yeast or fungal ID at genus or species level.

Subspecialty: ParasitologyWet mount of stool specimen/Pinworm Prep/Ova and Para-site ID by concentration or permanent stain.

Subspecialty: VirologyHerpes/RSV/CMV/Influenza A/Varicella-Zoster by AntigenDetection or Isolation and IB by Culture.

Subspecialty: Mycobacteriology Acid Fast Smears/Culture ID, susceptibility testing)

SPECIALTY: DIAGNOSTIC IMMUNOLOGY

Subspecialty: Syphilis Serology

Subspecialty: General ImmunologyAlpha-1-AntitrypsinAntinuclear AntibodyAnti-Streptolysin OAnti-Human Immunodeficiency Virus (HIV)Complement C3Complement C4Hepatitis marker (Hbs Ag)Hepatitis marker (Anti-HBc)Hepatitis marker (Hbe-Ag)IgAIgGIgEIgMInfectious MononucleosisRheumatoid FactorRubella

SPECIALTY: CHEMISTRY

Subspecialty: Routine ChemistryAlanine Aminotransferase (ALT)AlbuminAlkaline PhosphataseAmylaseAspartate Aminotransferase (AST)Bilirubin, TotalBlood Gases (pH/pO

2 /PCO

2 )

Calcium, TotalChlorideCholesterol, TotalCholesterol, HDLCreatine KinaseCreatine Kinase, Isoenzyme (CKMB)CreatinineGlucose (excluding devices cleared by FDA for home use)Iron, Total

REGULATED ANALYTES

© COLA--revised 5/99.COLA LabFacts® is a

registered trademark of COLA.