Albersheim 1989.

Methods	Blinding of randomization: yes (blocked randomization by the pharmacy) Blinding of intervention: yes Complete follow‐up: no. Of 35 patients recruited into the study, one was withdrawn from the study at parents request. Of 19 patients in the treatment group, 16 completed the study, 2 were discharged from the hospital during week 8 of the study and 1 patient was transferred to another hospital. Of 15 patients in the control group, 11 completed the study, 1 died on day 20 of the study, 2 were discharged from the hospital during week 8 of the study and 1 during week 6. Blinding of outcome: yes. Randomized controlled trial, parallel design No washout period
Participants	Patients entered into the study: n=35 Mechanical ventilation. Entry criteria included: chest radiograph compatible with BPD, postnatal age at least 1 month, ventilator dependency, oxygen requirement at least 30% O2, and full enteral feedings by gavage. The only exclusion criterion was failure to obtain informed consent from the parents.
Interventions	Thiazide and spironolactone vs placebo Patients were randomly allocated to receive either treatment (hydrochlorothiazide 2 mg/kg/12 hours enterally and spironolactone 1.5 mg/kg/12 hours enterally for 8 weeks) (N=19) or placebo (similar solution with same amount of sodium) (N=15). The study protocol was transiently discontinued if serum sodium concentration <125 mM/L or potassium < 3 mM/L, until electrolyte values returned to the normal range. Patients were allowed to receive furosemide if necessary, i.e., if the patient had excessive weight gain, clinical edema and deterioration or absence of expected improvement in respiratory status. Patients on the study were prevented from receiving corticosteroids, theophylline, or aerosolized bronchodilators.
Outcomes	Main outcome: survival at discharge Secondary outcomes: total numbers of ventilator days and of hospital days, pulmonary function, oxygen requirement, chest radiogram assessed using Edwards' criteria, number of doses of furosemide needed clinically.
Notes	Measurements of pulmonary function and FiO2 were obtained at baseline and at 1 week, 4 weeks and 8 weeks. Pulmonary mechanics were measured by the passive occlusion technique. Only intubated patients had pulmonary function tests performed. Fluid intake on weeks 4 and 8 of the study was 13% higher in the treatment group than in the control group (p<0.01 and <0.02, respectively, at 4 and 8 weeks).
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomized controlled trial, parallel design Blinding of randomization: yes (blocked randomization by the pharmacy)
Allocation concealment (selection bias)	Low risk	Blinding of randomization: yes (blocked randomization by the pharmacy)
Blinding (performance bias and detection bias) All outcomes	Low risk	Blinding of intervention: yes Blinding of outcome: yes
Incomplete outcome data (attrition bias) All outcomes	High risk	Complete follow‐up: no. Of 35 patients recruited into the study, one was withdrawn from the study at parents request. Of 19 patients in the treatment group, 16 completed the study, 2 were discharged from the hospital during week 8 of the study and 1 patient was transferred to another hospital. Of 15 patients in the control group, 11 completed the study, 1 died on day 20 of the study, 2 were discharged from the hospital during week 8 of the study and 1 during week 6
Other bias	High risk	Attrition bias: pulmonary mechanics were obtained only in intubated patients.