More than a billion laboratory tests that identify and measure chemicals, such as lead or cholesterol, are performed each year in the United States. Such test results have a significant influence on medical decisions.
Given the importance of laboratory test results, the Centers for Disease Control and Prevention's (CDC) National Center for Environmental Health has programs to help assure the quality of these data so patients and healthcare providers (as well as researchers and public health officials) can be confident that laboratory test results they receive are accurate. These CDC programs focus specifically on laboratory tests that are related to chronic diseases, newborn screening disorders, nutritional status, and environmental exposures.
Laboratory Quality Assurance (QA) encompasses a range of activities that enable laboratories to achieve and maintain high levels of accuracy and proficiency despite changes in test methods and the volume of specimens tested. A good QA system does these four things:
- establishes standard operating procedures (SOPs) for each step of the laboratory testing process, ranging from specimen handling to instrument performance validation;
- defines administrative requirements, such as mandatory recordkeeping, data evaluation, and internal audits to monitor adherence to SOPs;
- specifies corrective actions, documentation, and the persons responsible for carrying out corrective actions when problems are identified; and
- sustains high-quality employee performance.
Laboratory Standardization is achieved when test results with the same high levels of accuracy and precision can be reproduced across measurement systems, laboratories, and over time. Standardization depends on a rigorous process using:
- reference material—a sample of the analyte with a precisely known composition, which can be used to calibrate laboratory instruments and validate test protocols;
- a reference measurement procedure (RMP)—the "gold standard" measurement system for a particular analyte; and
- secondary measurement procedures—validated using reference material and RMP. These procedures may be less sophisticated than the RMP, but they are usually more easily implemented by a larger number of laboratories.
Well-executed standardization programs greatly improve the quality of laboratory measurements that are used to detect signs of illnesses and to guide interventions to prevent or treat illnesses. Standardization also ensures the production of credible and comparable data across laboratories—a boon to epidemiologists and researchers who may need to pool data from multiple sources.
CDC offers customized QA and standardization programs to help laboratories improve the quality and reliability of their measurement procedures. The specific CDC services that are offered are:
- Reference materials
- Proficiency testing
Each CDC laboratory QA and standardization program is voluntary and most are free of charge.