The Friedewald equation, which has been routinely used for decades to work out LDL cholesterol concentrations, is inaccurate and could be underestimating the risk of heart disease in high-risk patients, according to research published in the Journal of the American College of Cardiology. Developed in 1972 by William Friedewald, the eponymous equation has helped doctors around the world to assess patients' risk of developing heart disease and establish treatment regimens.