Rybo 1981.

Methods	Randomisation method not given Double‐blind placebo‐controlled trial with cross‐over design No loss to follow‐up
Participants	Sweden 18 women with a complaint of menorrhagia, ovulatory cycles and a normal coagulation test (data reported for subgroup of 4 women with primary menorrhagia, the remaining 12 had IUD‐induced menorrhagia) Exclusion criteria: organic cause of menorrhagia
Interventions	Group 1: naproxen 500 mg morning, 250 mg afternoon days 1 and 2, then 250 mg twice daily for up to 7 days, n = 4 Group 2: placebo same dosage regimen, n = 4 Duration: 2 + 2 cycles
Outcomes	MBL (alkaline haematin method)
Notes	Not ITT analysis Data not available at end of first cross‐over period and so not suitable for pooling Very large standard deviation for mean MBL in Rx group
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not stated
Allocation concealment (selection bias)	Unclear risk	Unclear risk
Blinding (performance bias and detection bias) All outcomes	Low risk	Double bind
Incomplete outcome data (attrition bias) All outcomes	Low risk	No dropouts reported
Other bias	Unclear risk	Nothing detected