A systematic review including 55 studies with a total of 2229 subjects (38 RCTs with a total of 1640 subjects) was abstracted in DARE. Biofeedback was associated with a small to medium statistically significant effect size on headache compared with waiting-list control (d=0.45, 95% CI: 0.26, 0.63; based on 14 effect sizes, n=574), but there was no significant different in effect size between BFB and placebo control, relaxation and ergotamine. In long-term (at least 6 months) studies biofeedback was associated with a medium-to-large statistically significant effect size on headache (d=0.69, 95% CI: 0.51, 0.88). Significant heterogeneity was found.
Comment: The quality of evidence is downgraded by study limitations (no intention-to-treat analysis) and inconsistency.