Explanation of the recommendations grading system
| Grade . | Recommendation . | Benefit vs risk and burdens . | Methodologic strength of supporting evidence . |
|---|---|---|---|
| 1A | Strong recommendation, high-quality evidence | Benefits clearly outweigh risk and burdens or vice versa | Consistent evidence from RCTs without important limitations or exceptionally strong evidence from OSs |
| 1B | Strong recommendation, moderate-quality evidence | Evidence from RCTs with important limitations* or very strong evidence from OSs | |
| 1C | Strong recommendation, low/very low-quality evidence | Evidence for at least 1 critical outcome from OSs, case series, or RCTs with serious flaws or indirect evidence | |
| 2A | Weak recommendation, high-quality evidence | Benefits closely balanced with risks and burden | Consistent evidence from RCTs without important limitations or exceptionally strong evidence from OSs |
| 2B | Weak recommendation, moderate-quality evidence | Evidence from RCTs with important limitations* or very strong evidence from OSs | |
| 2C | Weak recommendation, low/very low-quality evidence | Evidence for at least 1 critical outcome from OSs, case series, or RCTs with serious flaws or indirect evidence |
| Grade . | Recommendation . | Benefit vs risk and burdens . | Methodologic strength of supporting evidence . |
|---|---|---|---|
| 1A | Strong recommendation, high-quality evidence | Benefits clearly outweigh risk and burdens or vice versa | Consistent evidence from RCTs without important limitations or exceptionally strong evidence from OSs |
| 1B | Strong recommendation, moderate-quality evidence | Evidence from RCTs with important limitations* or very strong evidence from OSs | |
| 1C | Strong recommendation, low/very low-quality evidence | Evidence for at least 1 critical outcome from OSs, case series, or RCTs with serious flaws or indirect evidence | |
| 2A | Weak recommendation, high-quality evidence | Benefits closely balanced with risks and burden | Consistent evidence from RCTs without important limitations or exceptionally strong evidence from OSs |
| 2B | Weak recommendation, moderate-quality evidence | Evidence from RCTs with important limitations* or very strong evidence from OSs | |
| 2C | Weak recommendation, low/very low-quality evidence | Evidence for at least 1 critical outcome from OSs, case series, or RCTs with serious flaws or indirect evidence |
Modified from Guyatt et al.70
OS, observational studies; RCT, randomized controlled trial.
Important limitations are inconsistent results, methodologic flaws, or indirect or imprecise results.