TABLE 5-2 Dueling Evidence Hierarchies and Recommendation Grades in Cardiology

Intervention and Organization

Quality of the Evidence

Strength of the Recommendation

Therapy for oral anticoagulation in patients with atrial fibrillation and rheumatic mitral valve disease

American Heart Association

Level B

Class I

Scottish Intercollegiate Guidelines Network

Level 4

Grade C

American College of Chest Physicians

Grade C+

Grade 1C+

Implantable Cardioverter-Defibrillator therapy for cardiac arrest due to sustained ventricular fibrillation or ventricular tachycardia

American College of Cardiology/American Heart Association

Level A

Class I

Scottish Intercollegiate Guidelines Network

Level 3/4

Grade D

European Society of Cardiology

Level B

Class IIa

Carotid endarterectomy for internal carotid artery stenosis or symptomatic stenosis

American College of Cardiology/American Heart Association

Level C

Class IIa

American Academy of Neurology

Class I/II

Level A/B

Veterans Health Administration

Level I

Grade A

SOURCE: NGC (2007d); Schünemann et al. (2003).

lieve serves the needs of their specialty. Under that system, evidence from individual studies is rated as Level 1, 2, or 3; bodies of evidence are referred to as consistent or inconsistent; and the strength of recommendations are indicated by the letter A, B, or C (Ebell et al., 2004).

In addition to making efforts to reach agreement on grading scales, several groups have sought to standardize guideline development methodologies. Although there is still no internationally accepted standard for guideline development, there have been repeated calls for a “guideline for guidelines” (Guyatt et al., 2006b; Jackson and Feder, 1998; Schünemann et al., 2006; Shaneyfelt et al., 1999; Shekelle et al., 1999; Shiffman et al., 2003).

Among the more prominent efforts to standardize and raise the quality of clinical practice guidelines are the Appraisal of Guidelines Research and Evaluation (AGREE) collaboration and the Conference on Guideline Standardization (COGS). The AGREE collaboration defines the quality of guidelines as “the confidence that the potential biases inherent of guideline development have been addressed adequately and that the recommendations are both internally and externally valid, and are feasible for practice”



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