Olsen 1991.

Methods	This was a randomised, double‐blind, placebo‐controlled trial Setting Duke University Medical Center, Durham, USA Date of study Not reported (32‐week duration)
Participants	30 women Mean age (range) = 36.0 years (19 to 45) in the minoxidil group, 38.9 years (33 to 43) in the placebo group Inclusion criteria Female age 18 to 45 years. Dark hair. FPHL Ludwig scale grade I or II (Ludwig 1977), diagnosis based on clinical history/scalp hair loss pattern. Exclusion criteria Advanced hair loss. Using hormone therapy, oral contraceptives. Use of hair growth promoter, antihypertensives, anticonvulsants, ß‐blockers, steroids, cytotoxic drugs, vasodilators, diazoxide, or any drug with antiandrogen effects in prior 3 months. Concurrent evidence of anaemia, iron deficiency, or thyroid disease. Randomised 30 participants were randomised (15 to each of 2 groups) Withdrawals/losses to follow‐up There were 2/30 (6.7%) (1/group) withdrawals/losses to follow‐up. The time and reasons were unreported Baseline data Duration of hair thinning in mean (SD) years Minoxidil group = 10.07 (8.72), placebo group = 7.21 (1.06). Degree of thinning Ludwig scale (participants by grade and group) Grade I: minoxidil group = 9, placebo group = 9. Grade II: minoxidil group = 5, placebo group = 5. Number of non‐vellus hairs in the target area, mean (SD) Minoxidil group = 160.1 (34.63), placebo group = 154.2 (35.96).
Interventions	Intervention Minoxidil 2% solution. 1 mL of assigned solution applied to involved scalp twice daily for 32 weeks. Comparator Placebo (vehicle: propylene glycol, alcohol, water) solution. 1 mL of assigned solution applied to involved scalp twice daily for 32 weeks.
Outcomes	Assessments (9): at baseline, 4, 8, 12, 16, 20, 24, 28, and 32 weeks Primary outcomes (as reported) Hair counts at target area (frontoparietal tattooed), macro‐photography assessed.¹ Regrowth: subjective assessment (investigator/participant), rated none/minimal/moderate/dense regrowth.¹ Secondary outcomes (as reported) Adverse events: investigator‐assessed by clinical exam and questionnaire.¹ ¹Denotes outcomes prespecified for this review
Funding source	Quote (page 248): "This work was supported in part by a grant from the Upjohn Company"
Declaration of interest	None declared
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote (page 243): "were randomly assigned to apply". Comment: the trial authors did not report the method used to generate the allocation sequence in sufficient detail to allow a clear assessment of whether it would produce comparable groups.
Allocation concealment (selection bias)	Unclear risk	The trial authors did not report the method used to conceal the allocation sequence, that is to determine whether intervention allocations could have been foreseen in advance of, or during, enrolment. Comment: there was insufficient information to permit a clear judgement of the risk of bias.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Quote (page 244): "Both subjects and investigators remained blinded during the entire study." Comment: the report did not provide sufficient detail about the measures used to blind study participants and personnel from knowledge of which intervention a participant received, to permit a clear judgement.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote (page 245): "One technician at Duke University Medical Center blinded as to treatment counted the nonvellus target areas hairs on each set of before and after photographs." Comment: this was probably done.
Incomplete outcome data (attrition bias) All outcomes	Low risk	There was a balanced and low number (1 in each group) of losses to follow‐up. The data analysis was per‐protocol. Comment: we judged this as at a low risk of bias.
Selective reporting (reporting bias)	Low risk	The protocol for the study was unavailable, but the trial appears to have reported the prespecified outcomes and those mentioned in the methods section. Comment: we judged this as at a low risk of bias.
Other bias	Low risk	Comment: the study appeared to be free of other forms of bias.