Van't Veen 1998.

Methods	Study type: individual RCT Randomisation method: not mentioned Blinding: no (open‐label trial) Intention‐to‐treat analysis used: yes
Participants	Inclusion criteria of the trial Mild or moderate seborrhoeic dermatitis of the scalp Exclusion criteria of the trial People with plaques or severe crusts on the scalp or with signs suggestive of psoriasis Any underlying condition or concomitant treatment that might interfere with or account for SeD Use of systemic steroid during the 4 weeks preceding the study Pregnant and breastfeeding women Number of randomised participants: 69 in total (betamethasone N = 34, ketoconazole N = 35) Number of dropouts: 0 Sex: 33 males, 36 females Mean age (range): betamethasone arm = 45.6 (20 to 75) years, ketoconazole arm = 40.1 (18 to 73) years Country: the Netherlands
Interventions	Treatment Betamethasone 17‐valerate 0.1% lotion, applied to the scalp twice daily for the first week, once daily in the second week, and twice weekly in the third and fourth weeks Comparator/s Ketoconazole 20 mg/g hydrogel, applied to the scalp twice weekly for 4 weeks
Outcomes	Itching, scaling, and greasiness scores (scale 0 to 4) Overall improvement evaluated by participants and investigators (cured ‐ markedly improved ‐ improved ‐ unchanged ‐ worsened) Adverse events
Notes	"72 patients gave written informed consent and entered the wash‐out period, but 2 had spontaneous remission and 1 withdrew for a non‐study‐related reason leaving 69 patients randomized". The results were given in figures and not in exact numbers. We approximated the numbers from figures, where feasible
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	This was not reported in detail Quote: "randomly allocated"
Allocation concealment (selection bias)	Unclear risk	This was not reported in detail Quote: "randomly allocated"
Similarity of the study groups (selection bias)	Low risk	Quote: "The groups were very well matched for demography and clinical characteristics"
Blinding of participants (performance bias)	High risk	This was an open‐label study
Blinding of care providers (performance bias)	High risk	This was an open‐label study
Blinding of outcome assessment (detection bias) All outcomes	High risk	This was an open‐label study
Incomplete outcome data (attrition bias) All outcomes	Low risk	The dropout rate was acceptable
Selective reporting (reporting bias)	Low risk	All prespecified outcomes were reported, albeit not sufficiently enough for use in the meta‐analysis
Other bias	Unclear risk	1 author was affiliated to Glaxo‐Wellcome (The Netherlands) BV, and Glaxo‐Wellcome provided all products Quote: "Financial support for the study was generously provided by Glaxo‐Wellcome (The Netherlands) BV"