Migliardi 1994 Study 2.

Methods	6 individual studies reported, only the 2 'APAP/CAF' studies included Both multicentre, randomised, double‐blind, placebo‐controlled, 2‐period cross‐over studies. Single oral dose taken at the onset of at least moderate headache pain to treat 2 separate attacks per treatment period (ie 4 attacks in total). At least 48 h between first and second treatment in each period, and at least a 7‐day washout period before cross‐over 4‐h study period, with assessments at baseline, 0.5, 1, 2, 3, and 4 h post‐dose
Participants	Tension headache ‐ in accordance with IHS criteria and criteria established by the Ad Hoc Committee on the Classification of Headache. 6 to 7 tension headaches per month for at least 1 year that usually responded to OTC analgesics Participants with histories of other types of headache (for example, chronic, recurrent, continuous, migraine, or post‐traumatic) were excluded No other analgesics in the 8 h before treatment, or alcoholic beverages in the 6 h before. Caffeine was allowed before treatment, but any caffeine consumed in the preceding 4 h was noted at baseline Participants aged 18 to 65 years APAP/CAF Study 2: N = 442 (423 for efficacy) M 75, F 367 Mean age 33 years
Interventions	APAP/CAF Study 2: Paracetamol 1000 mg + caffeine 130 mg, n = 339 Paracetamol 1000 mg, n = 337 Placebo, n = 170
Outcomes	PI: standard 4‐point scale PR: standard 5‐point scale Withdrawals and dropouts Serious adverse events
Notes	Oxford Quality Score: R1, DB2, W1. Total = 4
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"double dummy technique"
Size	Low risk	> 200 participants in relevant treatment arms