The Very Large Database of Lipids (VLDL)

Closer examination of granular lipid data in a large population offers numerous opportunities to generate new knowledge, ranging from studies examining concordance between commonly used lipid parameters to phenotypic characterization of rare or extreme disorders of lipid metabolism, opening possibilities to better personalize future treatment of abnormal blood lipids.

STUDY POPULATION:

The Very Large Database of Lipids (VLDL) includes adults and children who were clinically referred for a Vertical Auto Profile (VAP).

LIPID MEASUREMENTS:

The VAP test (Atherotech, Birmingham, Alabama, USA) directly measures cholesterol concentrations of low density lipoprotein, very low density lipoprotein, intermediate density lipoprotein, high density lipoprotein, their subfractions, and lipoprotein(a). Triglycerides in the database are directly measured using the Abbott ARCHITECT C‐8000 system (Abbott Park, Illinois, USA). Lipid distributions in the database closely match those from the population-representative National Health and Nutrition Examination Survey (NHANES) 2007-2008.

STUDY PROCEDURES:

This database was investigator-initiated. Only de-identified data reach the investigational site. The first data harvest was in 2011, and encompassed 1,350,908 samples. The second harvest is underway; thus far, an updated database suited to assess seasonal variation has been established with 2,859,333 samples. The master database is housed at The Johns Hopkins Hospital in Baltimore, Maryland, and maintained by Drs. Jones and Martin. Only electronic data, and not biospecimens, are sent to Hopkins. The academic investigators have unrestricted access to study data, take responsibility for the accuracy of analyses, and have authority over manuscript preparation and submission.

VARIABLES:

The variables currently in the VLDL database are testing date, age, sex, low density lipoprotein, very low density lipoprotein, intermediate density lipoprotein, high density lipoprotein, their subfractions, lipoprotein(a), and LDL pattern. From these primary variables, many additional variables were derived for inclusion in the master database (e.g., non-HDL-C, Friedewald LDL-C, TC/HDL-C, etc.). Other analytes measured by validated assays in subsets of the VLDL database include apoB, apoA1, hsCRP, homocysteine, uric acid, insulin, hemoglobin A1c, 25-hydroxy vitamin D, cystatin C, Lp-PLA2, TSH, free T3 and T4, pro-BNP, direct bilirubin, CPK, creatinine and other components of the comprehensive metabolic panel, magnesium, and phosphate.

DATABASE ORGANIZATION:

In the current database, each record represents a unique patient. The 1st available VAP test for each patient is included. To meet the needs of a variety of research questions, we are prospectively planning to organize harvest 2 data into 3-year interval datasets (i.e., VLDL 2006-2008, 2009-2011, VLDL 2012-2014, etc), a summation dataset (first VAP test for each patient), serial lab dataset (patients who have had repeated testing), and ancillary datasets (subsets of patients with coexisting data on other measures such as apolipoproteins, vitamin D, hs-CRP, TSH/T4, etc).

INDIVIDUAL STUDIES:

Individual VLDL studies will be based on a priori hypotheses or aims with statistical analysis plans (SAPs) peer-reviewed prior to execution. In the expandable "Detailed Description" section below, the VLDL investigators will periodically register individual studies and update their status on clinicaltrials.gov.