Baran 1999.

Methods	This was a randomised, double‐blind, internally placebo‐controlled study. It was unclear if intention‐to‐treat analysis was conducted.
Participants	Inclusion criteria of the trial The trial included 27 consecutive participants with nail psoriasis (8 women, 19 men: age range = 22 to 79 years; average age = 47.0 years). Each participant was treated randomly with either the active formulation or the placebo lacquer. 1 participant dropped out, and 26 participants were evaluable.
Interventions	8% clobetasol‐17‐propionate in a colourless nail lacquer vehicle Placebo lacquer. The participants applied the placebo lacquer to one hand and the clobetasol lacquer to the other hand once daily until the end of treatment. The nail lacquer film was removed with a cosmetic nail varnish remover once weekly before a new application. The duration of treatment ranged between 1.2 and 6.6 months (average duration = 2.5 months).
Outcomes	Outcomes of the trial Therapeutic results on a 4‐point scale: cured, improved, failure, or worsened Observed features: onycholysis. pitting, subungual hyperkeratosis, salmon patches, splinter haemorrhages, ridging, transverse grooves, onychomadesis, and periungual psoriasis
Notes	There was a 1‐month wash‐out period for participants who had been treated with calcipotriol or steroid cream.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Each participant was treated randomly."
Allocation concealment (selection bias)	Unclear risk	Comment: The paper provided insufficient details.
Blinding (performance bias and detection bias) Clinician/ Investigator	Low risk	Quote: "...double‐blind study."
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 clinician was probably the assessor.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "27 consecutive participants with nail psoriasis were included, one dropped out during the study. At the end of the study, 26 participants were evaluable."
Selective reporting (reporting bias)	Low risk	Comment: The trial reported all prespecified outcomes.
Other bias	Low risk	Comment: This was free of other sources of bias.