Performance Standards for Allergen Skin Testing: An Approach to Proficiency Testing

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• 作者：Paul C. Turkeltaub ; MD^*
• 刊名：Immunology and Allergy Clinics of North America
• 出版年：2001
• 出版时间：1 May 2001
• 年：2001
• 卷：21
• 期：2
• 页码：321-328
• 全文大小：510 K

文摘

The importance ascribed to clinical laboratory tests with respect to having well-defined and validated methodology, test results that fall within acceptable limits for accuracy, precision, and sensitivity, and ongoing documentation that operators performing the test are proficient are the subject of federal regulations derived from the Clinical Laboratory Improvement Amendments (CLIA) of 1988. The Health Care Financing Administration (HCFA) operates the CLIA laboratory certification program in conjunction with the Center for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA). CLIA defines laboratory testing as ¡°the examination of materials derived from the human body for the purpose of providing information for the diagnosis, prevention, or treatment of any disease or impairment of, or the assessment of the health of human beings.?p>Under CLIA all entities providing laboratory testing are regulated and required by law to perform proficiency testing for specific tests. Proficiency testing involves sending blind sample specimens with defined properties to each laboratory during the year to evaluate whether the laboratory's results matches the samples' defined properties. Samples are required to be tested in the same manner and by the same individuals performing patient testing.

Results of proficiency test programs have been analyzed, resulting in the recognition that physician-operated testing laboratories experience a lower rate of successful test performance than traditional, previously regulated laboratories or physician-operated laboratories in which a laboratory professional provides supervision. The introduction of required proficiency testing has increased the accuracy of test results and quality of laboratory practice in physician-office laboratories, reflecting the positive impact of CLIA over time.

FDA-licensed allergen vaccines approved for diagnostic use commonly are employed clinically to detect cutaneous immediate hypersensitivity to allergens of interest. Results of allergen skin tests impact clinical decisions. Positive test results may indicate the likelihood of life-threatening hypersensitivity to food, insect, or drug allergens or the presence of environmental aeroallergens responsible for allergic disease. In each circumstance, there is an important impact on the quality of life in terms of the interventions designed to avoid exposure, the pharmaco- and immunotherapeutic interventions indicated to reduce the expected allergic response (if re-exposed), and the psychosomatic sequelae and economic cost to the patient associated with the diagnosis. The adverse impact if the test results are falsely positive or negative should be considered, and the attendent health and economic costs should be calculated. Similar considerations concerning the adverse impact of inaccurate tests on quality of health care lead to passage of CLIA to increase patient and physician confidence in the ability of tests to perform accurately according to objective standards, thus improving medical decisions and the quality of care and decreasing the economic burden of inaccurate test results.

Practice parameters for allergen skin testing specify that ¡°the proficiency of the skin tester should be validated by intrapatient and interpatient test results?and refer to proficiency tests and performance standards required by FDA for allergen standardization. In the latter context, investigators who submit allergen skin test data to the FDA to define the biologic potency of allergen vaccines for estimating US Standard of Potency and to estimate the cutaneous sensitivity of subjects enrolled in clinical trials submitted to FDA in support of the diagnostic or therapeutic efficacy of allergen vaccines are provided a skin test proficiency method. The method is ¡°suitable for assessing the proficiency of the operator who is carrying out this technique and can be used to qualify personnel for submission of skin test data to CBER.?Before submitting allergen skin test data to FDA, ¡°Investigators should be familiar with the Proficiency Method ?and have submitted proficiency data qualifying their use of this method.?p>The allergen skin test Proficiency Method based on the parallel line bioassay methodology described in 1982 has been subjected to international collaborative evaluation. It has been used in support of skin test data submitted to FDA in support of licensure of standardized cat, housedust mite, and grass pollen extracts (see FDA-approved package inserts that reference use of FDA skin test methods).

Test performance can be divided into two categories: analytical test performance and clinical test performance. Analytical test performance refers to the accuracy, precision, and sensitivity of a test to measure the analyte of interest. Clinical test performance is defined by the clinical accuracy of the test with respect to whether the test accurately discriminates between disease and nondisease states.