Erkko 1998.

Methods	Randomised, double‐blind, parallel‐arm trial Three centres in Helsinki, Gothenburg, and Stockholm Period of inclusion not stated
Participants	Inclusion criteria Clinically defined PPP of the palms and/or soles with at least 20 fresh pustules of at least 1 mm Age 18 to 70 years Exclusion criteria Pregnancy Kidney insufficiency Liver insufficiency Active infection Uncontrolled hypertension Past history of malignant tumours Baseline data: randomised to ciclosporin at a dose of 1.0 mg/kg per day (n = 27) or placebo (n = 31) Mean age (range), years: 45.2 (25 to 70), 43 (21 to 65) Male/female: 4/23; 12/19 Mean duration of condition (± SD), years: 7.2 ± 7·5; 5.4 ± 6 Proportion of participants with psoriatic lesions elsewhere: not specified Withdrawal: no dropouts
Interventions	Intervention A: ciclosporin 1 mg/kg/d twice daily for 1 month (27 participants) Control intervention B: placebo (31 participants) Co‐interventions: none Duration of treatment: 1 month
Outcomes	Primary outcome Response (reduction ≥ 50% in the number of fresh pustules) Secondary outcomes Score based on erythema, infiltration, and scaling (all from 0 to 3, estimated as 0, none; 1, slight; 2, moderate; 3, severe) and overall efficacy of treatment scored individually by both the patient and the investigator 2 months after the end of the treatment period using a score from 1 to 5 (1, very good; 2, good; 3, moderate; 4, slight; 5, none) Adverse events = tolerability of treatment (score: 1, very good; 2, good; 3, moderate; 4, slight; 5, none)
Notes	This work was supported by Novartis Pharma Ltd, Basel
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "The patients were given numbers in consecutive order at the various centres; each number had been pre‐assigned to start the study with treatment of either the traditional formulation of cyclosporin (Sandimmun) 1·0 mg/kg per day or placebo (vehicle without cyclosporin)" Comment: insufficient information about the sequence generation process to permit judgement
Allocation concealment (selection bias)	Unclear risk	Quote: "The patients were given numbers in consecutive order at the various centres; each number had been pre‐assigned to start the study with treatment of either the traditional formulation of cyclosporin (Sandimmun) 1·0 mg/kg per day or placebo (vehicle without cyclosporin)" Comment: the method to guarantee allocation concealment is not described
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "double‐blinded study" Comment: double‐blind placebo‐controlled trial. We consider blinding at low risk for trial vs placebo with no obvious clinical adverse events or known specific taste of experimental drug
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "double‐blinded study" Comment: double‐blind placebo‐controlled trial. We consider blinding at low risk for trial vs placebo with no obvious clinical adverse events or known specific taste of experimental drug
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "All 58 patients completed the double‐blind placebo‐controlled part 1 of the study" Comment: no dropouts
Selective reporting (reporting bias)	High risk	Comment: not all pre‐specified secondary outcomes are reported (scores), and no protocol is available to guarantee that all planned outcomes are presented in the results