Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Symptom improvement
Systematic review	47 people with plaque, pustular, or erythrodermic psoriasis affecting more than 20% of body surface; proportion of people with chronic plaque psoriasis not reported Data from 1 RCT	Proportion of people with marked improvement or clearance time of assessment not reported 20/25 (80%) with liquid oral 8-methoxsalen in PUVA 12/22 (55%) with crystalline oral 8-methoxsalen in PUVA	ARI +25% 95% CI –1% to +51%		Not significant