Foucan 1998.

Methods	Double‐blind, randomized, parallel, placebo‐controlled trial.
Participants	22 participants were enrolled into the study, in which 12 were in the treatment group and 10 were in the placebo group. All were homozygous for hemoglobin SS. Ages >18 years. Urinary albumin excretion between 30 mg and 300 mg per 24 hours on 3 different occasions in the 6 months prior to the study.
Interventions	Participants were were randomized into either: 1. captopril 6.25 mg/day for month 1, 12.5 mg/day for months 2 ‐ 3 and 25 mg/day for months 3 onward; or 2. placebo.
Outcomes	Primary outcomes include: urinary albumin (24 h), serum creatinine, sodium (results not stated), potassium Secondary outcomes include: hemoglobin concentration; blood pressure.
Notes	‐
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Random assignment. No process of generating allocation sequence was described.
Allocation concealment (selection bias)	Unclear risk	Not stated.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Intention‐to‐treat analysis was used. 2 participants were withdrawn from the study. Full reasons for withdrawal were given in the published paper.
Selective reporting (reporting bias)	High risk	Results for sodium level were not reported. Exact serum creatinine level and hemoglobin concentration were not reported.
Other bias	Low risk	No difference in baseline characteristics between the captopril group and placebo group.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Participants were blinded. Treating physicians were blinded.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Outcome assessors were blinded.