Table 1.

Risk of bias assessment for the included studies

	Ruby, 1973⁷	Zaynoun, 1974⁸	Eells, 1986⁹	Koning, 2002¹⁰	Koning, 2008¹¹	Gropper, 2014¹²	Rosen, 2018¹³
Defined sample: description of source of patients and inclusion and exclusion criteria	Hospital outpatient clinic. Describes some exclusion criteria, but not inclusion criteria	Hospital outpatient clinic. Does not describe inclusion or exclusion criteria	No mention of where trial was conducted. Describes inclusion and exclusion criteria	General practices. Describes inclusion and exclusion criteria	‘General practices and dermatology departments’. Describes inclusion and exclusion criteria	Unclear patient source: ‘27 centres in five countries’. Mentions ‘clinic visits’. Describes inclusion and exclusion criteria	Unclear patient source: multicountry and multicentre trial at various sites (clinic, hospital). Describes inclusion and exclusion criteria
Representative sample: participants were selected as consecutive cases	NR	NR	NR	NR	NR	NR	NR
Follow-up rate: outcome data available for ≤80% of participants at one follow-up point	NR	Yes	Yes	Yes	79% (n = 58/73) on day 14, per-protocol	Yes	Yes (but unequal loss between groups; more loss in placebo group)
Prognosis: raw data, percentages, survival rates, or continuous outcomes reported	Yes	Yes	Yes	Yes	Yes	Yes	Yes

NR = not reported.