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New cholesterol guideline improved accuracy of statin assignment vs. previous guideline
The 2013 American Heart Association/American College of Cardiology guideline on the assessment of CV risk more closely matched statin assignment to total plaque burden better than the previous 2001 National Cholesterol Education Program Adult Treatment Panel III guidelines.
Researchers conducted a study to determine which cholesterol guideline was associated with more accurate assignment of statin therapy and whether more patients would be assigned statins under the newest guidance.
Kevin M. Johnson, MD, from the department of diagnostic radiology at Yale University School of Medicine, and David A. Dowe, MD, from Atlantic Medical Imaging in Galloway, N.J., evaluated data from 3,076 patients who underwent CTA for various reasons, including stable atypical chest pain, strong family history and the presence of multiple risk factors. The cohort was 65.3% male, and the mean age was 55.4 years for men and 58.9 years for women. Risk estimation was performed and statin assignment was determined according to both the 2001 National Cholesterol Education Program (NCEP) Adult Treatment Panel III guideline and the 2013 AHA/ACC guideline on the assessment of CV risk (AHA/ACC).
The likelihood of statin prescription increased sharply with plaque burden, with better performance in all cases when patients were assessed according to the AHA/ACC guideline compared with the NCEP guideline. Fewer patients without plaque and more patients with heavy plaque would have been assigned to statin therapy under the AHA/ACC guideline compared with the NCEP guideline.
Patients with ≥50% stenosis in the left main coronary artery would not have been treated under the NCEP guidelines in 59% of cases, whereas those with ≥50% stenosis in other branches would not have been treated in 40% of cases. Under the AHA/ACC guideline, the estimated number of patients not treated in these circumstances would have been 18% and 10%, respectively.
Assignment to statin therapy occurred 15% more frequently under the AHA/ACC guideline than the NCEP guideline. The researchers noted that the accuracy of statin assignment under the NCEP guideline was substantially reduced by the use of LDL cholesterol targets. Assigning all patients at moderately high and high risk according to the NCEP guideline to statins, rather than utilizing LDL targets, yielded results similar to those observed under the AHA/ACC guideline.
“The 2013 guideline proposed by the AHA and the ACC results in a better discrimination of total plaque and stenosis burden than does the 2001 NCEP ATP III guideline,” the researchers concluded. “On the basis of our findings, it is a reasonable hypothesis that the new guideline will better predict coronary events, given that it better correlates with the severity of underlying atherosclerosis.”
In a related editorial, Robert A. Vogel, MD, from the Department of Veterans Affairs Medical Center in Denver, said this study supports earlier findings that the NCEP guidelines undertreated younger, high-risk patients and suggests that the AHA/ACC guideline represents a “major clinical and conceptual improvement.”
“The present study asks the fundamental question of whether guidelines are really distilled wisdom or simply working hypotheses,” Vogel wrote. “In a regulatory world in which the quality of medical care, and hence reimbursement, is evaluated by adherence to treatment guidelines, do guidelines need to be prospectively validated? Do we need fewer comments from experts and medical societies and more science? I would argue the latter. So does the present study.”
Disclosure: The researchers report no relevant financial disclosures. Vogel is the national coordinator of the ODYSSEY Outcomes phase 3 PCSK-9 trial, sponsored by Sanofi-Aventis.