Number of Studies	Study Design	Quality of Studies	Consistency	Directness	Other Modifying Factors
N	RCT = high Observational = low Any other evidence = very low	Serious limitation (-1) Very serious limitation (-2)	Important inconsistency (-1)	Same uncertainty (-1) Major uncertainty (-2)	Association Strong (+1) Very strong (+2) Dose response gradient (+1) All plausible confounders would have reduced the effect (+1) Imprecise or sparse data (-1) High of reporting bias (-1)

^*Grade Working Group (97)