Expert panel’s guideline on cervicogenic headache: The Chinese Association for the Study of Pain recommendation

Table 2 Grading of Recommendations, Assessment, Development and Evaluation system for strength of recommendations

Recommendation strength	Definition
Strong	When the desirable effects of an intervention clearly outweigh the undesirable effects or clearly do not
Weak (‘‘conditional’’ or‘‘discretionary’’)	When the trade-offs are less certain either because of low-quality evidence or because evidence suggests that desirable and undesirable effects are closely balanced