More structured guidelines including word limits ( tar- gets ) and a web guideline supplement for useful but noncritical tables and figures are 2 such changes. This Preamble is an abbreviated version, with the detailed version available online. Glenn N. Levine, MD, FACC, FAHA Chair, ACC/AHA Task Force on Clinical Practice Guidelines 1.1. Methodology and Evidence Review The recommendations listed in the present guideline are, whenever possible, evidence based. An initial ex- tensive evidence review, which included literature de- rived from research involving human subjects, published in English, and indexed in MEDLINE (through PubMed), EMBASE, the Cochrane Library, the Agency for Health- care Research and Quality, and other selected databases relevant to the present guideline, was conducted from May 1980 to July 2017. Key search words included but were not limited to the following: hyperlipidemia, cholesterol, LDL-C, HDL-C, ezetimibe, bile acid seques- trants, PCSK9 inhibitors, lifestyle, diet, exercise, medica- tions, child, adolescent, screening, primary prevention, secondary prevention, cardiovascular disease, coronary artery calcium, familial hypercholesterolemia. ASCVD risk-enhancing factors, statin therapy, diabetes melli- tus, women, adherence, Hispanic/Latino, South Asian, African American. Additional relevant studies published through August 2018 during the guideline writing pro- cess, were also considered by the writing committee and added to the evidence tables when appropriate. The final evidence tables are included in the Online Data Supplement and summarize the evidence used by the writing committee to formulate recommendations. References selected and published in the present docu- ment are representative and not all-inclusive. As noted in the detailed version of the Preamble, an independent evidence review committee was commis- sioned to perform a formal systematic review of critical clinical questions related to cholesterol (Table 1), the Table 1. 