“…The most common outcome measured was headache intensity via the visual analogue scale (VAS) (24,26,30–34), the numerical rating scale (NRS) (25,27,29,35–38), the verbal rating scale (28) or the 3-point severity index of the headache disability inventory (HDI) (39,40). Headache frequency was measured via a headache diary (1 week to 3 months) (23,25,26,28–32,35,36,38), the 3-point scale of the HDI (39,40), a 4-point scale (33) or a 5-point Likert scale (27). Quality of life was measured in three studies (24,38,41) (using SF-12 and SF-36) and headache duration was evaluated in five studies (25,28,30,31,38).…”