Rigopoulos 2007.

Methods	This was a randomised, double‐blind, actively‐controlled study. It was unclear if intention‐to‐treat analysis was conducted.
Participants	Inclusion criteria of the trial The study included 46 psoriatic participants with nail symptoms.
Interventions	The first group applied tazarotene 0.1% cream (Zorac®) to the affected nail plates, surrounding nail folds, and periungual skin under occlusion at bed time for 12 weeks. The second group applied clobetasol propionate 0.05% cream (Butavate) in the same way. Occlusion was performed after application of the cream using common transparent membrane obtained through general stores.
Outcomes	Outcomes of the trial Outcome measures were assessed at baseline and at weeks 4, 8, and 12 using the Nail Psoriasis Severity Index (NAPSI) to grade the following parameters independently: pitting, onycholysis, subungual hyperkeratosis, and salmon patches. Follow‐up evaluation was performed 12 weeks after the end of the therapy.
Notes	A 12‐week wash‐out period was allowed for topical and systematic medications. 3 of 16 participants in the tazarotene group reported adverse events: desquamation and erythema of nail fold skin, periungual irritation, paronychia, and irritation of the skin of the toe or finger distanced from the nail area. 1 of 14 participants in the clobetasol group reported a sensation of burning on the nail fold skin.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "The participants were randomly assigned by a computer." Comment: This was probably done.
Allocation concealment (selection bias)	Low risk	Quote: "...assignment by a computer." Comment: This was probably done.
Blinding (performance bias and detection bias) Clinician/ Investigator	Low risk	Quote: "...double blind study, investigators were blinded regarding the agent applied by each participant."
Blinding (performance bias and detection bias) Participants	Low risk	Quote: "...double blind study."
Blinding (performance bias and detection bias) Outcome assessor	Low risk	Quote: "...double blind study." Comment: The blinded investigator was probably the outcome assessor.
Incomplete outcome data (attrition bias) All outcomes	High risk	There were 16 dropouts (7 in the tazarotene group, and 9 in the clobetasol group): 10/16 had urgent need for systemic therapy; 4 of 16 failed to keep to the follow‐up schedule; and 2 had missing outcome data.
Selective reporting (reporting bias)	Low risk	All of the expected outcomes were reported.
Other bias	Unclear risk	There was no information about baseline characteristics. Both agents were given in identical containers.