“…Tables S1 present the general characteristics of the studies included in the meta‐analysis. The studies consisted of 1 historical cohort, 3 case–control, and 37 cross‐sectional studies 6,8,9,20–57 . Thirty‐three studies (31 publications) were included in the analysis of migraine, 6,8,9,20,27,29,30,32–44,47–57 11 studies (9 publications) in the analysis of TTH, 28,36,45–47,49,52,55,57 11 studies (7 publications) in the analysis of headache, 20,24–26,45,47,49 3 studies in the analysis of CDH, 22,23,45 2 studies in the analysis of nonmigraine headache, 35,50 4 studies in the analysis of chronic migraine, 42,51,52,57 and 5 studies (3 publications) in the analysis of episodic migraine 31,39,51 .…”