Laboratory data
All laboratory blood and urine analyses included in the AMORIS cohort were performed on fresh blood/urine samples by the CALAB laboratory. For 51% of the subjects in the cohort, information is available on repeated blood samples, sometimes exceeding 50 analyses over the time period until 1996.
The original CALAB laboratory database includes 35,815,102 laboratory values recorded for 595 biomarkers (Table 2). The majority of analyses (90%) concerns chemistry and hematology biomarkers (1993-1996) but there are also measurements representing immunology, allergy, bacteriology, and viral serology.
Laboratory data sections analyzed in the AMORIS cohort
Several chemistry biomarkers were part of a standard analysis package including novel analyses not requested by the referring physician such as apoB, apoA-I and the apoB/apoA-I ratio for specification of dyslipidemia, and fructosamine for diagnosis of diabetes. Since CALAB was an international leader and frontrunner for the development of health screening and automation in laboratory practice (Autochemist ®), investigations on potentially valuable risk markers for future use were also performed. More details on CALAB automation methodology with some of the early results from AMORIS studies can be found in references [1-5]. For example, the following serum biomarkers have been used to assess lipid profiles: triglycerides, total cholesterol, LDL- and HDL-cholesterol, apoB, apoA-I, and a variety of lipid ratios. Lipid and apolipoprotein assessment methods have been described and validated in detail by Walldius [4-5] and Talmud [6].
Table 3 shows a range of key biomarkers for the AMORIS cohort and the number of analyses available for each biomarker. These analyses include repeated samples for the same individual but several biomarkers have been measured at least once for more than 500,000 individuals.
Key biomarkers for the AMORIS cohort and number of analyses available for each biomarker
About 53% of chemistry biomarkers were known to be measured under overnight fasting conditions, 9% had been fasting for four hours and 2% for two hours. It is possible to restrict the analyses to only those subjects who were taking part in a repeated and standardized yearly health screening program (26% of the AMORIS cohort).
For all biomarkers in the CALAB database the method used for analysis, including changes in the analytical procedures have been well documented and are stored at Karolinska Institutet. All analytical procedures for measuring lipids and apolipoproteins were compliant with the WHO International Federation of Clinical Chemistry protocols standard programs and were computerized with systems for automatic calibration [1,3,4,5] with an extensive quality control scheme used. For example, the accuracy of total cholesterol and triglyceride values was checked against standards from the National Institute of Standards and Technology, Gaithersburg, MD, USA, or against analyses done at lipid reference laboratories certified by the US Centres for Disease Control. Virtually all of the methods used by the CALAB laboratory were performed by automated techniques and instrumentation as more closely described in papers 1-5.
References
1. Jungner I, Walldius G, Holme I, Kolar W, Steiner E. Apolipoprotein B and A-I in relation to serum cholesterol and triglycerides in 43,000 Swedish males and females. Int J Clin Lab Res. 1992;21(3):247-55.
2. Walldius G, Jungner I, Kolar W, Holme I, Steiner E. High cholesterol and triglyceride values in Swedish males and females: increased risk of fatal myocardial infarction. First report from the AMORIS (Apolipoprotein related MOrtality RISk) study. Blood Press Suppl. 1992;4:35-42.
3. Jungner I, Marcovina SM, Walldius G, Holme I, Kolar W, Steiner E. Apolipoprotein B and A-I values in 147576 Swedish males and females, standardized according to the World Health Organization-International Federation of Clinical Chemistry First International Reference Materials. Clin Chem. 1998;44:1641-719.
4. Walldius G, Jungner I, Holme I, Aastveit AH, Kolar W, Steiner E. High apolipoprotein B, low apolipoprotein A-I, and improvement in the prediction of fatal myocardial infarction (AMORIS study): a prospective study. Lancet. 2001 Dec 15;358(9298):2026-33.
5. Peterson HE, Jungner I: The History of the AutoChemist. From Vision to Reality. Yearb Med Inform. 2014;9:235-43.
6. Talmud PJ, Hawe E, Miller GJ, Humphries SE. Nonfasting apolipoprotein B and triglyceride levels as a useful predictor of coronary heart disease risk in middle-aged UK men. Arterioscler Thromb Vasc Biol 2002;22:1918-23.