Program History and Background
In 1986, the Centers for Disease Control and Prevention (CDC) implemented
the Model Performance Evaluation Program (MPEP) to evaluate the performance of
laboratories conducting testing to detect human immunodeficiency virus type 1
(HIV-1) antibody (Ab). Since that time, the MPEP has been expanded to include
the evaluation of performance for several other tests. Recently, due to changes
in programmatic needs, the human T-lymphotropic virus types I and II
(HTLV-I/II) antibody and HIV p24 antigen programs were discontinued.
The following table summarizes the history of the MPEP:
Test |
Year Included in Program
|
Year Discontinued |
HIV-1 Antibody
|
1986
|
|
HTLV-I/II Antibody
|
1989 |
2002 |
TLI* |
1990
|
|
HIV-1 RNA (Viral Load) |
1996
|
|
HIV-1 p24 Antigen
|
1996
|
2002 |
HIV-1 Rapid |
2003 |
|
* T-lymphocyte Immunophenotyping - CD4 T-cell enumeration
Program Purpose
High-quality HIV-1 antibody testing is essential to meeting the public
health objectives for the prevention and control of this retrovirus infection.
High quality TLI and viral HIV-1 RNA (viral load) determinations are essential
to HIV-infected patient care and management, and the mission of reducing
retrovirus-associated morbidity and mortality. Prevention programs, diagnostic
clinics, and seroprevalence studies rely not only on accurate antibody testing
results to document HIV infection, but also accurate TLI, and HIV-1 viral RNA
determinations. The impetus for developing this program came from the
recognized need to assess the quality of retroviral and AIDS-related laboratory
testing and to ensure that the quality of HIV-1 and HTLV-I/II Ab testing, TLI,
HIV-1 viral RNA determinations, and HIV-1 p24 Ag testing was adequate to meet
medical and public health needs. The objectives of the MPEP are to:
(1) Develop appropriate methods for evaluating quality in laboratory testing
systems (including test selection, sample collection, and reporting and
interpreting test results)
(2) Develop strategies for identifying and correcting testing quality failures
(3) Evaluate the effect of testing quality on public health.
Program Design
The MPEP is designed to analyze the steps in the total testing process and
to identify the critical indicators of high-quality testing. Annually, the MPEP
mails two performance evaluation sample panels each for HIV-1 Ab, TLI, and
HIV-1 viral RNA. Participant laboratories are requested to test the performance
evaluation (PE) samples that CDC mails them in the same manner they test
routine clinical specimens, and to report their testing results to CDC on
specially designed forms. Aggregate data are derived from the testing results
of enzyme immunoassay (EIA), Western blot (WB), indirect immunofluorescence
assay (IFA), radioimmuno-precipitation assay (RIPA), other tests, TLI cell
counts and percentages, or copies of HIV-1 viral RNA, provided to CDC by each
of the laboratories. CDC is responsible for compiling and analyzing the results
and sends aggregate reports of testing results to all participant laboratories
following each PE survey. In addition to sample panel surveys, participant
laboratories are asked to complete a survey questionnaire every other year
describing the characteristics of their laboratory and their testing practices.
The MPEP is not proficiency testing. The MPEP provides detailed analysis of
aggregate data and does not grade results from individual laboratories. Graded
laboratory proficiency testing surveys are conducted, for example, by the
College of American Pathologists (CAP) and the American Association of
Bioanalysts (AAB). Of the approximately 850 laboratories enrolled in the MPEP
for HIV-1 Ab testing, nearly 80% are also enrolled in programs sponsored by CAP
or AAB.
Participation
The PE surveys are provided free of charge to participant laboratories. The
PE surveys depend upon a wide spectrum of laboratory participation to generate
a representative data base. To accurately assess the quality of laboratory
testing, we need the participation of laboratories representing all levels of
performance. Past CDC experience has shown that participation in PE surveys
leads to improved testing performance. By encouraging participation in the PE
surveys, CDC is giving participant laboratories an opportunity for
self-improvement and, in addition, a basis for developing prevention and
intervention strategies. Interest in the program is quite high; approximately
90 percent of the laboratories receiving sample panels respond with results.
This high rate of participation indicates strong support for achieving the goal
of improving and maintaining high quality laboratory testing.
Recruitment for volunteer enrollment in the MPEP is ongoing by CDC (to date more
than 17,000 laboratories have been contacted). Not all of the laboratories
contacted perform HIV-1 Ab testing, TLI, or HIV-1 viral RNA determinations, but
of those that do perform these tests and participate in the MPEP, approximately
850 perform HIV-1 Ab testing, 300 perform TLI and 225 perform HIV-1 viral RNA
determinations.
Reports
The reports sent to participant laboratories following each PE evaluation
survey consist of tables and graphical figures, grouped for each performance
evaluation sample, by test kit manufacturer, test method, WB band patterns, and
IFA intensity, for example. A written analysis of results accompanies each
final report. Although the MPEP is not a regulatory program, laboratories find
the aggregate reports of testing results beneficial in comparing their results
with those from other laboratories. This practice affords each laboratory the
opportunity for self-improvement and serves as a vehicle to accomplish an
important objective of the MPEP: improving and maintaining high quality
testing. Periodic brief reports highlighting important findings are sent to
MPEP participants, usually after aggregate reports have been distributed.
Reprints from CDC Morbidity and Mortality Weekly Report (MMWR) publications
and from CDC authored peer-reviewed journal publications concerning retroviral
or AIDS-related testing are also sent to participant laboratories.
Assessing Preanalytic and Post analytical Processes
To identify and assess barriers to high-quality laboratory testing in
preanalytic and postanalytic steps of the total testing process for HIV-1 Ab,
TLI, and HIV-1 RNA (viral load), CDC collaborates with the Association of
Schools of Public Health and San Diego State University Graduate School of
Public Health to develop systematic analyses for identifying variables in the
steps of the testing process. These analyses are used to assist in cataloging
events that occur from the time tests are requested through specimen
collection, laboratory analyses, and reporting of test results so that
potential problems, particularly in the preanalytic and postanalytic steps of
the testing process, can be identified and corrected. Some of these analyses
include:
- Examination the variability of viral load and CD4 T-cell testing laboratory
reports and adherence to published testing guidelines.
-Identification of nonanalytic issues in HIV-1 antibody testing using blind
proficiency testing.
-Use of a nominal group process for improving the performance of laboratories
conducting HIV antibody testing
-Personnel competency assessments.
MPEP Focus on Laboratory Practices
Through PE survey data and ongoing research, the MPEP evaluates laboratory
practices linked to high quality performance. The focus is on answering such
questions as the following:
-What are the testing practices and characteristics of laboratories that test
for HIV-1 Ab, perform TLI, or determine HIV-1 viral RNA?
-Do these practices affect quality in the laboratory testing process?
-Is the high quality of laboratory testing dependent upon the nature of the
laboratory itself, e.g., public health versus blood collection center versus
hospital-based laboratory versus independent laboratory, numbers of samples
tested, types and sequence of tests performed, internal and external quality
assurance procedures implemented throughout the testing process, education and
training of testing personnel, or experience of personnel performing the
testing?
-What strategies for correcting quality failures are most effective and how can
they be implemented?
MPEP Products
Currently, we provide the following:
-Reports to participants: These reports contain graphical figures and analyses
of the PE sample survey and questionnaire results, which are useful indicators
in detecting performance deficiencies and quality results.
-Publications: MPEP Performance Bulletins addressing specific testing
performance issues, MMWR articles describing specific aspects of performance
results, and peer-reviewed journal publications directly addressing testing
issues.
-Statistical analyses: Examination of participant laboratory data to develop a
profile of the characteristics which distinguish a laboratory testing process
that performs consistently well from one that performs poorly. This information
is essential for targeting strategies for improving the quality of laboratory
testing.
Future Plans
Future plans of the MPEP include:
(1) Refinements in existing programs, such as performance panels to evaluate new
methods in HIV-1 Ab testing (particularly in the area of rapid testing), new or
changing methods in performing TLI, and new methods in determining HIV-1 viral
RNA
(2) Provision of online performance data submission
(3) Expansion of the survey design to broaden our knowledge about the level of
quality in the preanalytic and postanalytic steps of the testing process
(4) Recommendations for intervention strategies for laboratory improvement.
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