About the Program
The objective of the LSP is to provide participating laboratories with a structured, validated system to standardize the analysis of total cholesterol (TC), triglyceride (TG), and high-density lipoprotein cholesterol (HDL-C).
The primary goals of the CDC- LSP are to:
- reduce variation in measurements among laboratories regardless of test methodology used; and
- link serum lipid and lipoprotein measurements to an accuracy base supported by CDC's Lipid Reference Laboratory using established reference measurement procedures (RMPs).
- link serum apolipoprotein measurements to an accuracy base supported by Northwest Lipid Metabolism and Diabetes Research Laboratories (NWLMDRL) using IFCC-WHO accepted reference materials.
The LSP is available to the following types of US and international laboratories:
- Laboratories supporting epidemiological studies and clinical trials
- Lipid research laboratories
- State/local public health laboratories
- Reference laboratories
- International lipid laboratories supporting epidemiological and clinical trials.
Enrolled laboratories are asked to analyze fresh-frozen human serum reference materials to assess the trueness (measurement bias or systematic error) of their analytical system(s). The LSP provides high-quality human serum-based reference materials that have been value-assigned using the CDC reference measurement procedures or NWLMDRL designated comparison methods. These reference materials must be stored at -70°C. The CDC reference samples are provided to the participant as unknowns; each set of pooled human serum-based materials is labeled with blind-coded identification numbers.
To effectively standardize lipid testing, participating laboratories must perform the following activities:
- Develop and maintain technical proficiency with their analytical system(s).
- Develop and maintain quality-control (QC) systems for effectively evaluating and documenting measurement precision for each analyte standardized.
- Use a calibration process that produces accurate results with the analytical system.
Proficiency Testing Program vs. Lipid Standardization Program
Most proficiency testing (PT) programs evaluate how well a laboratory conducts analytical testing in comparison with other laboratories using the same analytical systems. Many of these programs rely on comparisons based on peer grouping to assess accuracy rather than on a statistically based relationship to a recognized standard. In addition, conventional PT assessments are generally provided at only a few intervals during each testing year. Further, because of matrix effects that are characteristic of PT materials; laboratories are not able to establish traceability to an accepted accuracy base.
Conversely, the CDC-LSP is an accuracy-based program that differs from the PT programs in which many clinical laboratories participate to meet federal and state regulatory requirements. The LSP is designed to improve the participating laboratory's analytical accuracy and precision performance by standardizing results over the entire analytical testing period. Traceability is therefore established for each method by linking the measured values for each analyte to the accuracy base maintained by the CDC Lipid Reference Laboratory. PT programs are generally based on comparison to peer-group means, which are calculated at specific points in time with limited data and provide no mechanism for establishing, assessing, or improving accuracy.
The CDC-LSP produces pools of fresh human serum using an accepted process that minimizes the alteration of the natural serum matrix. This process results in serum-based materials that are frozen only once - after preparation and dispensing - thus avoiding commonly observed freeze-thaw effects. In contrast, with some analytical systems, performance assessment by proficiency testing can be complicated by matrix effects often associated with highly processed testing materials that are often made from previously collected and stored serum. As a result, different systems produce different analytical results for the same testing material. Such matrix interactions make calibration and standardization difficult, which can lead to inaccurate patient results and erroneous conclusions about analytical system performance. Successful performance in the LSP requires not only use of rigorously prepared human serum-based reference materials, but also that a participant's analytical system exhibit negligible matrix effects when using CDC reference materials. This ensures reliable assessments of analytical performance for each LSP participant.