Classification	Criteria
I	Prospective cohort study with all relevant confounders controlled, masked or objective outcome assessments, and a) ≤2 primary outcomes, b) clearly defined inclusion/exclusion criteria c) ≥80% study completion rate.
II	Retrospective cohort study or case‐control study meeting all other class I criteria.
III	Cohort study or case‐control study meeting all class I or II criteria except a, b, or c above.
IV	Studies not meeting Class I, II, or III criteria