Table 1

Schedule of procedures

Observation/procedure	Person undertaking the specified event	Visit
Observation/procedure	Person undertaking the specified event	Screening/baseline	Week 6	Week 12	End of treatment/week 24 contact	End of study/final follow-up questionnaire (52 weeks or sooner)*
Enrolment
Informed consent	Nurse/other clinician†	X
Eligibility evaluation	Other clinician	X
Participant characteristics	Nurse/other clinician	X
Blood pressure	Nurse/other clinician	X
Blood tests (serum potassium, eGFR)	Nurse/other clinician	X
Pregnancy test	Nurse/other clinician	X
Randomisation	Nurse/other clinician	X
Assessments
IGA	Nurse/other clinician	X	X	X
Medical history	Participant	X
Self-assessment—Participant’s Global Assessment (adapted IGA)	Participant	X	X	X	X	X
Acne medication use	Nurse/other clinician/participant	X	X	X	X	X
Other medication use	Nurse/other clinician/participant	X
Acne-QoL	Participant	X	X	X	X	X
EQ-5D-5L	Participant	X	X	X	X	X
Resource use questionnaire	Participant	X	X	X	X	X
Self-assessment—comparison with baseline photo—6-point Likert Scale	Participant		X	X	X	X
Collection of ARs of special interest Headache Dizziness/vertigo/light headedness Tingling Indigestion/heartburn/dyspepsia Diarrhoea Polyuria (passing much more urine than normal) Nausea/feeling sick Vomiting/being sick Tenderness of the breasts Breast enlargement Irregular menstrual periods Abdominal pain Weight gain Reduced libido (reduced interest in sex) Fatigue/tiredness Drowsiness/sleepiness	Participant/other clinician		X	X	X
Serious adverse events	Other clinician (PI or delegate)		X	X	X
Assessment of treatment response to determine dose adjustment‡	Participant/other clinician		X	X
Satisfaction with study treatment	Participant				X
Other activities
Discuss use of contraception	Nurse/other clinician	X	X	X
Photographs of face taken	Nurse/other clinician	X
Photographs given to participant	Nurse/other clinician	X		X (if a set was stored at site)
Letter to participant’s GP (patient participation)	Nurse/other clinician	X
Check participant is not using oral acne treatment	Nurse/other clinician/participant		X	X
Return excess IMP to clinic	Participant		X	X	X (return via post)
Spironolactone/placebo pill count	Nurse/other clinician/participant		X	X	X
Letter to participant’s GP (if dose is changed)	Nurse/other clinician		X	X
Reminder to participant to report any subsequent adverse event(s) that might reasonably be related to participation in this study (up to 52 weeks)	Nurse/other clinician			X
Ask participants if they would like to receive a summary of the study results, when available	Nurse/other clinician			X
Letter to participant (unblinding)					X (after 24 weeks)
Letter to participant’s GP (unblinding)					X (after 24 weeks)

*The follow-up questionnaire will be sent out 6 months or sooner after the 24-week time point.
†Dermatologist or clinical research fellow, in line with local procedures with demonstrable and appropriate level of training. Specific duties delegated by the PI and listed on the delegation log.
‡Dose escalated to two tablets per day if participant is tolerating side effects.
Acne-QoL, Acne-specific Quality of Life; AR, adverse reactions; eGFR, estimated glomerular filtration rate; GP, general practitioner; IGA, Investigator’s Global Assessment; IMP, investigational medicinal product; PI, Principal Investigator.