Evaluation of a new equation for LDL-c estimation and prediction of death by cardiovascular related events in a German population-based study cohort

Abstract

A simple equation established by Cordova & Cordova (LDL-COR) was developed to provide an improved estimation of LDL-cholesterol in a large Brazilian laboratory database. We evaluated this new equation in a general population cohort in Pomerania, north-eastern Germany (SHIP Study) compared to other existing formulas (Anandaraja, Teerakanchana, Chen, Hattori, Martin, Friedewald and Ahmadi), and its power in the prediction of death by atherosclerosis related events as the primary outcome. Analysis was conducted on a cohort of 4075 individuals considering age, gender, use of lipid lowering therapy and associated co-morbidities such as diabetes, hepatic, kidney and thyroid disease. LDL-COR values had a lower standard deviation compared to the previously published equations: 0.92 versus 1.02, 1.02, 1.03, 1.04, 1.09, 1.10 and 1.74 mmol/L, respectively. All of the factors known to affect the results obtained by the Friedewald’s equation (LDL-FW), except fibrate use, were associated with the difference between LDL-COR and LDL-FW (p < .01), with TSH being borderline (p = .06). LDL-COR determined a higher hazard ratio (1.23 versus 1.12, 1.19, 1.21, 1.19, 1.21 and 1.19) for cardiovascular disease related mortality, incident stroke or myocardial infarction compared to the other evaluated formulas, except for Ahmadi’s (1.24), and the same adjusted predictive power considering all confounding factors. The proposed simple equation was demonstrated to be suitable for a more precise LDL-c estimation in the studied population. Since LDL-c is a parameter frequently requested by medical laboratories in clinical routine, and will probably remain so, precise methods for its estimation are needed when direct measurement is not available.

Keywords:

• Lipids
• lipoproteins
• cardiovascular diagnostic technics
• LDL cholesterol
• cardiovascular diseases
• mortality
• proportional hazards models
• myocardial infarction
• stroke

Acknowledgements

The authors are grateful to the German Academic Exchange Service (DAAD) and the Brazilian Higher Education Personnel Improvement Coordination (CAPES), to the University of Blumenau, Brazil (FURB), the University of Greifswald, the city of Pomerode, Brazil and the city of Greifswald, Germany.

Disclosure statement

The authors have no competing interest to disclose.

Data availability statement

The datasets on which the conclusions of the manuscript rely are not publicly available and are regulated by the SHIP Study Rules for the Use and Handling of Data and Samples. They can be requested at http://www.fvcm.med.uni-greifswald.de/.

Geolocation information

The SHIP study region was defined by the cities and rural districts of Stralsund (54°18′N 13°5′E), Greifswald (54°5′N 13°23′E), and Anklam (53°51′N 13°41′E) (without the island of Usedom and without Fischland/Darsz) (http://www2.medizin.uni-greifswald.de/cm/fv/ship/studienbeschreibung/).

Additional information

Funding

The Study of Health in Pomerania (SHIP) is part of the Community Medicine Research net (CMR) (http://www.medizin.uni-greifswald.de/icm) of the University of Greifswald, supported by grants from the German Federal Ministry of Education and Research (BMBF, grants 01ZZ96030, 01ZZ0701), by the German Competence Network Heart Failure, and the network ‘Greifswald Approach to Individualized Medicine (GANI_MED)’. The GANI_MED consortium is supported by the German Federal Ministry of Education and Research as well as by the Ministry of Cultural Affairs of the German Federal State of Mecklenburg–West Pomerania (grant 03IS2061A). This study was carried out in collaboration with the DZHK (German Centre for Cardiovascular Research), which is supported by the German Federal Ministry of Education and Research (BMBF), and the EU supported BiomarCare consortium. CMMC and ETSH were supported by fellowships from the German Academic Exchange Service (DAAD) and the Brazilian Higher Education Personnel Improvement Coordination (CAPES).