Abstract
Objectives
Low-density lipoprotein cholesterol (LDLC) is the primary cholesterol target for the diagnosis and treatment of cardiovascular disease (CVD). Although beta-quantitation (BQ) is the gold standard to determine LDLC levels accurately, many clinical laboratories apply the Friedewald equation to calculate LDLC. As LDLC is an important risk factor for CVD, we evaluated the accuracy of Friedewald and alternative equations (Martin/Hopkins and Sampson) for LDLC.
Methods
We calculated LDLC based on three equations (Friedewald, Martin/Hopkins and Sampson) using the total cholesterol (TC), triglycerides (TG), and high-density lipoprotein cholesterol (HDLC) in commutable serum samples measured by clinical laboratories participating in the Health Sciences Authority (HSA) external quality assessment (EQA) programme over a 5 years period (number of datasets, n=345). LDLC calculated from the equations were comparatively evaluated against the reference values, determined from BQ-isotope dilution mass spectrometry (IDMS) with traceability to the International System of Units (SI).
Results
Among the three equations, Martin/Hopkins equation derived LDLC had the best linearity against direct measured (y=1.141x − 14.403; R2=0.8626) and traceable LDLC (y=1.1692x − 22.137; R2=0.9638). Martin/Hopkins equation (R2=0.9638) had the strongest R2 in association with traceable LDLC compared with the Friedewald (R2=0.9262) and Sampson (R2=0.9447) equation. The discordance with traceable LDLC was the lowest in Martin/Hopkins (median=−0.725%, IQR=6.914%) as compared to Friedewald (median=−4.094%, IQR=10.305%) and Sampson equation (median=−1.389%, IQR=9.972%). Martin/Hopkins was found to result in the lowest number of misclassifications, whereas Friedewald had the most numbers of misclassification. Samples with high TG, low HDLC and high LDLC had no misclassification by Martin/Hopkins equation, but Friedewald equation resulted in ∼50% misclassification in these samples.
Conclusions
The Martin/Hopkins equation was found to achieve better agreement with the LDLC reference values as compared to Friedewald and Sampson equations, especially in samples with high TG and low HDLC. Martin/Hopkins derived LDLC also enabled a more accurate classification of LDLC levels.
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Research funding: None declared.
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Author contributions: All authors have accepted responsibility for the entire content of this manuscript and approved its submission.
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Competing interests: Authors state no conflict of interest.
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Informed consent: Not applicable.
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Ethical approval: This study was based on the results from a local external quality assessment program with the effort to assess the performance of the measurement procedures of the local clinical laboratories. Such quality assessment program is exempted from local institutional ethics review.
References
1. Grundy, SM, Stone, NJ, Bailey, AL, Beam, C, Birtcher, KK, Blumenthal, RS, et al.. 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA guideline on the management of blood cholesterol: executive summary: a report of the American college of cardiology/American heart association task force on clinical practice guidelines. Circulation 2019;139:e1046–81. https://doi.org/10.1161/CIR.0000000000000624.Search in Google Scholar PubMed
2. Authors/Task Force Members; ESC Committee for Practice Guidelines (CPG); ESC National Cardiac Societies. 2019 ESC/EAS guidelines for the management of dyslipidaemias: lipid modification to reduce cardiovascular risk. Atherosclerosis 2019;290:140–205. https://doi.org/10.1016/j.atherosclerosis.2019.08.014.Search in Google Scholar PubMed
3. Collins, R, Reith, C, Emberson, J, Armitage, J, Baigent, C, Blackwell, L, et al.. Interpretation of the evidence for the efficacy and safety of statin therapy. Lancet 2016;388:2532–61. https://doi.org/10.1016/s0140-6736(16)31357-5.Search in Google Scholar PubMed
4. Baigent, C, Blackwell, L, Emberson, J, Holland, LE, Reith, C, Bhala, N, et al., Cholesterol Treatment Trialists’ (CTT) Collaboration. Efficacy and safety of more intensive lowering of LDL cholesterol: a meta-analysis of data from 170,000 participants in 26 randomised trials. Lancet 2010;376:1670–81. https://doi.org/10.1016/s0140-6736(10)61350-5.Search in Google Scholar PubMed PubMed Central
5. Myers, GL, Cooper, GR, Greenberg, N, Kimberly, MM, Waymack, PP, Hassemer, DJ. Standardization of lipid and lipoprotein measurements. In: Rifai, N, Warnick, GR, Dominiczak, MH, editors. Handbook of lipoprotein testing, 2nd ed. Washington, D.C.: American Association for Clinical Chemistry (AACC); 2000:717–48 pp.Search in Google Scholar
6. Nakamura, M, Kayamori, Y, Iso, H, Kitamura, A, Kiyama, M, Koyama, I, et al.. LDL cholesterol performance of beta quantification reference measurement procedure. Clin Chim Acta 2014;431:288–93. https://doi.org/10.1016/j.cca.2014.02.018.Search in Google Scholar PubMed PubMed Central
7. Friedewald, WT, Levy, RI, Fredrickson, DS. Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge. Clin Chem 1972;18:499–502. https://doi.org/10.1093/clinchem/18.6.499.Search in Google Scholar
8. Jialal, I, Inn, M, Siegel, D, Devaraj, S. Underestimation of low density lipoprotein-cholesterol with the Friedewald equation versus a direct homogenous low density lipoprotein-cholesterol assay. Lab Med 2017;48:220–4. https://doi.org/10.1093/labmed/lmx023.Search in Google Scholar PubMed
9. Scharnagl, H, Nauck, M, Wieland, H, März, W. The Friedewald formula underestimates LDL cholesterol at low concentrations. Clin Chem Lab Med 2001;39:426–31. https://doi.org/10.1515/cclm.2001.068.Search in Google Scholar PubMed
10. Wilson, PW, Zech, LA, Gregg, RE, Schaefer, EJ, Hoeg, JM, Sprecher, DL, et al.. Estimation of VLDL cholesterol in hyperlipidemia. Clin Chim Acta 1985;151:285–91. https://doi.org/10.1016/0009-8981(85)90091-9.Search in Google Scholar PubMed
11. Jun, KR, Park, HI, Chun, S, Park, H, Min, WK. Effects of total cholesterol and triglyceride on the percentage difference between the low-density lipoprotein cholesterol concentration measured directly and calculated using the Friedewald formula. Clin Chem Lab Med 2008;46:371–5. https://doi.org/10.1515/CCLM.2008.064.Search in Google Scholar PubMed
12. Nauck, M, Warnick, GR, Rifai, N. Methods for measurement of LDL-cholesterol: a critical assessment of direct measurement by homogeneous assays versus calculation. Clin Chem 2002;48:236–54. https://doi.org/10.1093/clinchem/48.2.236.Search in Google Scholar
13. Miida, T, Nishimura, K, Okamura, T, Hirayama, S, Ohmura, H, Yoshida, H, et al.. A multicenter study on the precision and accuracy of homogeneous assays for LDL-cholesterol: comparison with a beta-quantification method using fresh serum obtained from non-diseased and diseased subjects. Atherosclerosis 2012;225:208–15. https://doi.org/10.1016/j.atherosclerosis.2012.08.022.Search in Google Scholar PubMed
14. Miller, WG, Myers, GL, Sakurabayashi, I, Bachmann, LM, Caudill, SP, Dziekonski, A, et al.. Seven direct methods for measuring HDL and LDL cholesterol compared with ultracentrifugation reference measurement procedures. Clin Chem 2010;56:977–86. https://doi.org/10.1373/clinchem.2009.142810.Search in Google Scholar PubMed PubMed Central
15. Martin, SS, Blaha, MJ, Elshazly, MB, Toth, PP, Kwiterovich, PO, Blumenthal, RS, et al.. Comparison of a novel method vs the Friedewald equation for estimating low-density lipoprotein cholesterol levels from the standard lipid profile. JAMA 2013;310:2061–8. https://doi.org/10.1001/jama.2013.280532.Search in Google Scholar PubMed PubMed Central
16. Sampson, M, Ling, C, Sun, Q, Harb, R, Ashmaig, M, Warnick, R, et al.. A new equation for calculation of low-density lipoprotein cholesterol in patients with normolipidemia and/or hypertriglyceridemia. JAMA Cardiol 2020;5:540–8. https://doi.org/10.1001/jamacardio.2020.0013.Search in Google Scholar PubMed PubMed Central
17. Sathiyakumar, V, Park, J, Golozar, A, Lazo, M, Quispe, R, Guallar, E, et al.. Fasting versus nonfasting and low-density lipoprotein cholesterol accuracy. Circulation 2018;137:10–9. https://doi.org/10.1161/circulationaha.117.030677.Search in Google Scholar PubMed
18. Brownstein, AJ, Martin, SS. More accurate LDL-C calculation: externally validated, guideline endorsed. Clin Chim Acta 2020;506:149–53. https://doi.org/10.1016/j.cca.2020.03.030.Search in Google Scholar PubMed
19. Cao, J, Remaley, AT, Guan, W, Devaraj, S, Tsai, MY. Performance of novel low-density lipoprotein-cholesterol calculation methods in predicting clinical and subclinical atherosclerotic cardiovascular disease risk: the multi-ethnic study of atherosclerosis. Atherosclerosis 2021;327:1–4. https://doi.org/10.1016/j.atherosclerosis.2021.04.018.Search in Google Scholar PubMed
20. Ferrinho, C, Alves, AC, Bourbon, M, Duarte, S. Applicability of Martin-Hopkins formula and comparison with Friedewald formula for estimated low-density lipoprotein cholesterol in e_COR study population. Rev Port Cardiol 2021;40:715–24. https://doi.org/10.1016/j.repce.2021.07.001.Search in Google Scholar PubMed
21. Chapman, MJ, Ginsberg, HN, Amarenco, P, Andreotti, F, Borén, J, Catapano, AL, et al.. Triglyceride-rich lipoproteins and high-density lipoprotein cholesterol in patients at high risk of cardiovascular disease: evidence and guidance for management. Eur Heart J 2011;32:1345–61. https://doi.org/10.1093/eurheartj/ehr112.Search in Google Scholar PubMed PubMed Central
22. Farukhi, Z, Mora, S. Re-assessing the role of non-fasting lipids; a change in perspective. Ann Transl Med 2016;4:431. https://doi.org/10.21037/atm.2016.11.15.Search in Google Scholar PubMed PubMed Central
23. Khan, SH, Niazi, NK, Sobia, F, Fazal, N, Manzoor, SM, Nadeem, A. Friedewald’s equation for calculating LDL-cholesterol: is it the time to say “Goodbye” and adopt direct LDL cholesterol methods? Pakistan J Med Sci 2019;35:388–93. https://doi.org/10.12669/pjms.35.2.679.Search in Google Scholar PubMed PubMed Central
24. Lee, J, Jang, S, Jeong, H, Ryu, OH. Validation of the Friedewald formula for estimating low density lipoprotein cholesterol: the Korea national health and nutrition examination survey, 2009 to 2011. Korean J Intern Med 2020;35:150–9. https://doi.org/10.3904/kjim.2017.233.Search in Google Scholar PubMed PubMed Central
25. Zafrir, B, Saliba, W, Flugelman, MY. Comparison of novel equations for estimating low-density lipoprotein cholesterol in patients undergoing coronary angiography. J Atheroscler Thromb 2020;27:1359–73. https://doi.org/10.5551/jat.57133.Search in Google Scholar PubMed PubMed Central
26. Singh, G, Hussain, Y, Xu, Z, Sholle, E, Michalak, K, Dolan, K, et al.. Comparing a novel machine learning method to the Friedewald formula and Martin-Hopkins equation for low-density lipoprotein estimation. PLoS One 2020;15:e0239934. https://doi.org/10.1371/journal.pone.0239934.Search in Google Scholar PubMed PubMed Central
27. Martínez-Morillo, E, García-García, M, Concha, MAL, Varas, LR. Evaluation of a new equation for estimating low-density lipoprotein cholesterol through the comparison with various recommended methods. Biochem Med 2021;31:010701. https://doi.org/10.11613/bm.2021.010701.Search in Google Scholar
28. Song, Y, Lee, HS, Baik, SJ, Jeon, S, Han, D, Choi, SY, et al.. Comparison of the effectiveness of Martin’s equation, Friedewald’s equation, and a Novel equation in low-density lipoprotein cholesterol estimation. Sci Rep 2021;11:13545. https://doi.org/10.1038/s41598-021-92625-x.Search in Google Scholar PubMed PubMed Central
29. Vargas-Vázquez, A, Bello-Chavolla, OY, Antonio-Villa, NE, Mehta, R, Cruz-Bautista, I, Aguilar-Salinas, CA. Comparative assessment of LDL-C and VLDL-C estimation in familial combined hyperlipidemia using Sampson’s, Martin’s and Friedewald’s equations. Lipids Health Dis 2021;20:46. https://doi.org/10.1186/s12944-021-01471-3.Search in Google Scholar PubMed PubMed Central
30. Briers, PJ, Langlois, MR. Concordance of apolipoprotein B concentration with the Friedewald, Martin-Hopkins, and Sampson formulas for calculating LDL cholesterol. Biochem Med 2022;32:010704. https://doi.org/10.11613/bm.2022.010704.Search in Google Scholar
31. Ertürk Zararsız, G, Bolat, S, Cephe, A, Kochan, N, Yerlitaş, Sİ, Doğan, HO, et al.. Validation of Friedewald, Martin-Hopkins and Sampson low-density lipoprotein cholesterol equations. PLoS One 2022;17:e0263860. https://doi.org/10.1371/journal.pone.0263860.Search in Google Scholar PubMed PubMed Central
32. Palmer, MK, Barter, PJ, Lundman, P, Nicholls, SJ, Toth, PP, Karlson, BW. Comparing a novel equation for calculating low-density lipoprotein cholesterol with the Friedewald equation: a VOYAGER analysis. Clin Biochem 2019;64:24–9. https://doi.org/10.1016/j.clinbiochem.2018.10.011.Search in Google Scholar PubMed
33. Abell, LL, Levy, BB, Brodie, BB, Kendall, FE. A simplified method for the estimation of total cholesterol in serum and demonstration of its specificity. J Biol Chem 1952;195:357–66. https://doi.org/10.1016/s0021-9258(19)50907-3.Search in Google Scholar
34. Manita, D, Yoshida, H, Koyama, I, Nakamura, M, Hirowatari, Y. Verification of low-density lipoprotein cholesterol levels measured by anion-exchange high-performance liquid chromatography in comparison with beta quantification reference measurement procedure. J Appl Lab Med 2021;6:654–67. https://doi.org/10.1093/jalm/jfaa144.Search in Google Scholar PubMed
35. Ćwiklińska, A, Wieczorek, E, Gliwińska, A, Marcinkowska, M, Czaplińska, M, Mickiewicz, A, et al.. Non-HDL-C/TG ratio indicates significant underestimation of calculated low-density lipoprotein cholesterol (LDL-C) better than TG level: a study on the reliability of mathematical formulas used for LDL-C estimation. Clin Chem Lab Med 2020;59:857–67. https://doi.org/10.1515/cclm-2020-1366.Search in Google Scholar PubMed
36. Myers, GL, Eckfeldt, JH, Greenberg, N, Levine, JB, Miller, WG, Wiebe, DA. Preparation and validation of commutable frozen human serum pools as secondary reference materials for cholesterol measurement procedures approved guideline. CLSI document C37-A. Wayne, PA: Clinical and Laboratory Standards Institute; 1999.Search in Google Scholar
37. Danilenko, U, Vesper, HW, Myers, GL, Clapshaw, PA, Camara, JE, Miller, WG. An updated protocol based on CLSI document C37 for preparation of off-the-clot serum from individual units for use alone or to prepare commutable pooled serum reference materials. Clin Chem Lab Med 2020;58:368–74. https://doi.org/10.1515/cclm-2019-0732.Search in Google Scholar PubMed PubMed Central
38. Ellerbe, P, Meiselman, S, Sniegoski, LT, Welch, MJ, White, VE. Determination of serum cholesterol by a modification of the isotope dilution mass spectrometric definitive method. Anal Chem 1989;61:1718–23. https://doi.org/10.1021/ac00190a025.Search in Google Scholar PubMed
39. Ellerbe, P, Sniegoski, LT, Welch, MJ. Isotope dilution mass spectrometry as a candidate definitive method for determining total glycerides and triglycerides in serum. Clin Chem 1995;41/3:397–404. https://doi.org/10.1093/clinchem/41.3.397.Search in Google Scholar
40. Chen, Y, Liu, Q, Yong, S, Teo, HL, Lee, TK. An improved reference measurement procedure for triglycerides and total glycerides in human serum by isotope dilution gas chromatography–mass spectrometry. Clin Chim Acta 2014;428:20–5. https://doi.org/10.1016/j.cca.2013.10.014.Search in Google Scholar
41. Bachorik, PS, Ross, JW. National cholesterol education program recommendations for measurement of low-density lipoprotein cholesterol: executive summary. The national cholesterol education program working group on lipoprotein measurement. Clin Chem 1995;41:1414–20. https://doi.org/10.1093/clinchem/41.10.1414.Search in Google Scholar
42. Miller, M, Stone, NJ, Ballantyne, C, Bittner, V, Criqui, MH, Ginsberg, HN, et al.. Triglycerides and cardiovascular disease: a scientific statement from the American heart association. Circulation 2011;123:2292–333. https://doi.org/10.1161/cir.0b013e3182160726.Search in Google Scholar PubMed
43. Martin, SS, Giugliano, RP, Murphy, SA, Wasserman, SM, Stein, EA, Ceška, R, et al.. Comparison of low-density lipoprotein cholesterol assessment by Martin/hopkins estimation, Friedewald estimation, and preparative ultracentrifugation: insights from the FOURIER trial. JAMA Cardiol 2018;3:749–53. https://doi.org/10.1001/jamacardio.2018.1533.Search in Google Scholar PubMed PubMed Central
44. Sajja, A, Park, J, Sathiyakumar, V, Varghese, B, Pallazola, VA, Marvel, FA, et al.. Comparison of methods to estimate low-density lipoprotein cholesterol in patients with high triglyceride levels. JAMA Netw Open 2021;4:e2128817. https://doi.org/10.1001/jamanetworkopen.2021.28817.Search in Google Scholar PubMed PubMed Central
45. Langlois, MR, Nordestgaard, BG, Langsted, A, Chapman, MJ, Aakre, KM, Baum, H, et al.. Quantifying atherogenic lipoproteins for lipid-lowering strategies: consensus-based recommendations from EAS and EFLM. Clin Chem Lab Med 2020;58:496–517. https://doi.org/10.1515/cclm-2019-1253.Search in Google Scholar PubMed
46. Kang, M, Kim, J, Lee, SY, Kim, K, Yoon, J, Ki, H. Martin’s equation as the most suitable method for estimation of low-density lipoprotein cholesterol levels in Korean adults. Korean J Fam Med 2017;38:263–9. https://doi.org/10.4082/kjfm.2017.38.5.263.Search in Google Scholar PubMed PubMed Central
47. Chaen, H, Kinchiku, S, Miyata, M, Kajiya, S, Uenomachi, H, Yuasa, T, et al.. Validity of a novel method for estimation of low-density lipoprotein cholesterol levels in diabetic patients. J Atheroscler Thromb 2016;23:1355–64. https://doi.org/10.5551/jat.35972.Search in Google Scholar PubMed PubMed Central
48. Pallazola, VA, Sathiyakumar, V, Ogunmoroti, O, Fashanu, O, Jones, SR, Santos, RD, et al.. Impact of improved low-density lipoprotein cholesterol assessment on guideline classification in the modern treatment era-results from a racially diverse Brazilian cross-sectional study. J Clin Lipidol 2019;13:804–11.e2. https://doi.org/10.1016/j.jacl.2019.07.002.Search in Google Scholar PubMed
49. Mehta, R, Reyes-Rodríguez, E, Yaxmehen Bello-Chavolla, O, Guerrero-Díaz, AC, Vargas-Vázquez, A, Cruz-Bautista, I, et al.. Performance of LDL-C calculated with Martin’s formula compared to the Friedewald equation in familial combined hyperlipidemia. Atherosclerosis 2018;277:204–10. https://doi.org/10.1016/j.atherosclerosis.2018.06.868.Search in Google Scholar PubMed
50. Sonoda, T, Takumi, T, Miyata, M, Kanda, D, Kosedo, I, Yoshino, S, et al.. Validity of a novel method for estimating low-density lipoprotein cholesterol levels in cardiovascular disease patients treated with statins. J Atheroscler Thromb 2018;25:643–52. https://doi.org/10.5551/jat.44396.Search in Google Scholar PubMed PubMed Central
51. Martin, SS, Ditmarsch, M, Simmons, M, Alp, N, Turner, T, Davidson, MH, et al.. Comparison of low-density lipoprotein cholesterol equations in patients with dyslipidaemia receiving cholesterol ester transfer protein inhibition. Eur Heart J Cardiovasc Pharmacother 2023;9:148–55. https://doi.org/10.1093/ehjcvp/pvac056.Search in Google Scholar PubMed PubMed Central
52. Sun, CJ, McCudden, C, Brisson, D, Shaw, J, Gaudet, D, Ooi, TC. Comparison of three methods for LDLC calculation for cardiovascular disease risk categorization in three distinct patient populations. Can J Cardiol 2022;S0828-282X:01121–7. https://doi.org/10.1016/j.cjca.2022.12.025.Search in Google Scholar PubMed
53. Ertürk Zararsız, G, Bolat, S, Cephe, A, Kochan, N, Yerlitaş, SI, Doğan, HO, et al.. Validation of low-density lipoprotein cholesterol equations in pediatric population. PeerJ 2023;11:e14544. https://doi.org/10.7717/peerj.14544.Search in Google Scholar PubMed PubMed Central
54. Sajja, A, Li, HF, Spinelli, KJ, Blumenthal, RS, Virani, SS, Martin, SS, et al.. Discordance between standard equations for determination of LDL cholesterol in patients with atherosclerosis. J Am Coll Cardiol 2022;79:530–41. https://doi.org/10.1016/j.jacc.2021.11.042.Search in Google Scholar PubMed
Supplementary Material
This article contains supplementary material (https://doi.org/10.1515/cclm-2022-1301).
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