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Laboratory methods and quality assurance in the Cardiovascular Health Study
M Cushman1, E S Cornell, P R Howard
1Department of Pathology, University of Vermont College of Medicine, Burlington 05401.
Insights
This study details quality assurance for blood sample analysis in the Cardiovascular Health Study. Rigorous methods ensured reliable data collection for cardiovascular disease risk factor research in older adults.
Area of Science:
- Cardiovascular Health
- Clinical Laboratory Science
- Epidemiology
Background:
- The Cardiovascular Health Study (CHS) is a major observational cohort study investigating cardiovascular disease risk factors.
- Focusing on 5201 participants aged 65 years and older, the study requires robust data integrity.
- Ensuring accurate laboratory analysis is crucial for valid epidemiological findings.
Purpose of the Study:
- To report the methods and quality-assurance (QA) results for blood sample handling and analysis during the CHS's first examination period (May 1989-June 1990).
- To evaluate the reliability and consistency of laboratory procedures for epidemiological research.
- To identify and address challenges in blood procurement, processing, shipping, storage, and analysis.
Main Methods:
- Detailed description of blood procurement, processing, shipping, storage, and laboratory analysis protocols.
- Implementation of standard QA methods, including coefficient of variation (CV) for control materials.
- Application of advanced QA techniques: technical error calculation for replicates and weighted linear regression for time-trend analysis of control materials.
Main Results:
- The most common phlebotomy/processing issue was the need for multiple venipunctures (2.6% of participants).
- CVs for control materials generally remained low (most < 4%), with glucose at 0.93% and insulin at 10.7%.
- Technical error values, after outlier exclusion, ranged from 1.7% (uric acid) to 18.8% (insulin). Slight trends were observed for Factor VII and Factor VIII over 12 months.
Conclusions:
- The implemented quality-assurance analyses were successful in identifying and resolving issues.
- These QA efforts significantly improved the laboratory examination process for subsequent study periods.
- The rigorous QA procedures support the reliability of cardiovascular disease risk factor data collected in the CHS.
Abstract:
The Cardiovascular Health Study is an observational cohort study of risk factors for cardiovascular disease in 5201 participants, ages > or = 65 years. We report the methods and quality-assurance results for blood procurement, processing, shipping, storage, and sample analysis used during the first examination period (May 1989-June 1990). The most frequent difficulty in phlebotomy and processing was the requirement of more than one venipuncture (in 2.6% of the participants). The CVs for control materials ranged from 0.93% for glucose to 10.7% for insulin; most were < 4%. In addition to standard quality-assurance methods, we applied two other methods: technical error calculation for replicates, and weighted linear regression to assess time trend in results of control materials. After outliers were excluded, technical error values ranged from 1.7 for uric acid to 18.8 for insulin. Factor VII and factor VIII had slight trends over the 12-month analysis period. Results of quality-assurance analyses used to resolve problems were successful, thereby improving the second laboratory examination.