Navigating Clinical Grading Systems: COR, LOE, & SORT-By Tahir Khwaja 

                                                                                                               COR vs LOE vs SORT

Class of Recommendation (COR) and Level of Evidence (LOE) are standardized grading systems used in clinical
practice guidelines by the American College of Cardiology (ACC) and the American Heart Association (AHA) to improve cardiovascular health. Together, these grading systems provide recommendations for patients with cardiovascular disease or at risk of developing it. COR describes the strength of recommendation, while LOE describes the quality of evidence. On the other hand, Strength of Recommendation Taxonomy (SORT) was developed by the American Academy of Family Physicians (AAFP) as a grading scale used by many family medicine and primary care journals.

Class of Recommendation grading chart
The extent of benefit in contrast to risk
    ● Class I: Strong Recommendation; strongly beneficial/useful/effective and should be performed or administered.
    ● Class IIa: Moderate recommendation; could be useful/beneficial and is reasonable.
    ● Class IIb: Weak recommendation; may be reasonable; however, impact is unclear.
    ● Class III (No Benefit): Moderate recommendation; not beneficial and should not be performed.
    ● Class III (Harm): Strong Recommendation; potentially causes harm and should not be performed.

Level of Evidence grading chart
The rating for the quality of the scientific evidence
    ● Level A: Strongest evidence based on multiple high-quality randomized controlled trials or meta-analyses
    ● Level B-R (Randomized): Good evidence based on 1 or more moderate-quality randomized trials.
    ● Level B-NR (Non-Randomized): Moderate quality based on one or more well-executed non-randomized studies, registry studies, or observational studies.
    ● Level C-LD (Limited Data): Flawed randomized or nonrandomized studies, observational/registry data, or basic human physiological studies.
    ● Level C-EO (Expert Opinion): Lowest level of evidence; based completely on an expert's judgment over study data.

Strength of Recommendation Taxonomy grading chart
Measurement of patient outcome
    ● Level A - patient-oriented evidence of high quality.
    ● Level B - patient-oriented evidence of limited quality.
    ● Level C - other evidence based on consensus, opinion, or experience.

References
1. Ebell, M. H., et al. “Strength of recommendation taxonomy (SORT): A patient-centered approach to grading evidence in the medical literature.” The Journal of the American Board of Family Medicine, vol. 17, no. 1, 1 Jan. 2004, pp. 59–67, https://doi.org/10.3122/jabfm.17.1.59.
2. Arnett, Donna K., et al. “2019 ACC/AHA Guideline on the Primary Prevention of Cardiovascular Disease.” Journal of the American College of Cardiology, vol. 74, no. 10, Mar. 2019, pp. e177–232. https://doi.org/10.1016/j.jacc.2019.03.010



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