Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Headache duration, frequency, or intensity
[27] Systematic review	152 people 2 RCTs in this analysis	Headache frequency (mean number of days with headache/month) 8 weeks with SSRIs (sertraline or citalopram) with amitriptyline Absolute results not reported	MD +0.76 95% CI –2.05 to +3.57 P = 0.60		Not significant
[27] Systematic review	152 people 2 RCTs in this analysis	Headache severity (assessed on a 10-point scale [VAS or ordinal scale]) 8 weeks with SSRIs (sertraline or citalopram) with amitriptyline Absolute results not reported	MD +0.32 95% CI –0.55 to +1.19 P = 0.47 Heterogeneity: I2 = 72%; P = 0.06		Not significant
[27] Systematic review	152 people 2 RCTs in this analysis	Headache duration (mean hours/day) 8 weeks with SSRIs (sertraline or citalopram) with amitriptyline Absolute results not reported	MD 1.26 95% CI 0.06 to 2.45 P = 0.04	Effect size not calculated	amitriptyline