Table 5.

“Within-Guideline” Analysis: Relative Odds of a Downgrade, Reversal, or Omission According to Level of Evidence for 448 Index Recommendations That Had Available Level-of-Evidence Data, Holding Constant All Guideline-Level Factors^a

	Odds Ratio for Downgrade, Reversal, or Omission (95% CI)	P Value
Level of evidence A: multiple randomized clinical trials or meta-analyses	1 [Reference]
Level of evidence B: single randomized trial or nonrandomized studies	3.14 (1.69–5.85)	<.001
Level of evidence C: consensus opinion, case studies, or standard of care	3.49 (1.45–8.41)	.005

^aLevel-of-evidence data were available for 448/619 (72.4%) index recommendations in our sample; level-of-evidence data were not provided for recommendations in the 1998 guideline on valvular heart disease or the 2002 guideline on perioperative evaluation and care. Odds ratios were obtained via conditional logistic regression grouped by the individual guideline; all standard errors were robust and adjusted for clustering at the guideline level.