Kao 1984.

Methods	Blinding of randomization: yes. The code of randomization was compiled using a table of randomly assorted digits. Blinding of intervention: yes. Diuretics and placebo were each labeled using a code ("drug 1" or "drug 2"), the identity of which was unknown to nurses who administered the drugs. Complete follow up: yes Blinding of outcome: yes Randomized clinical trial with cross‐over design; data during first exposure kept separate from those after cross‐over. Washout period: 48 hr before the study, none at cross‐over
Participants	Patients entered into the study: n=10 No mechanical ventilation, no O2 requirement. Entry criteria: (1) Gestational age < 34 weeks; (2) history of RDS defined as air bronchogram and reticulogranular pattern on initial radiographs, cyanosis in room air, and grunting and retractions within the first 24 hours of life; (3) FiO2 > 0.40 and mechanical ventilation during the first 5 days of life; (4) continued need for mechanical ventilation, FiO2 > 0.30 and radiographic evidence of stage 3 or 4 of BPD by 1 month of age. Exclusion criteria: patent ductus arteriosus, mechanical ventilation or oxygen therapy at the time of study, other lung disease (e.g., pneumonia, meconium aspiration, pulmonary hypoplasia).
Interventions	Thiazide and spironolactone vs thiazide and placebo Diuretic and bronchodilator therapy were discontinued 48 hours before beginning study. Patients were then randomly allocated to receive either: (1) chlorothiazide 40 mg/kg/day and spironolactone 3 mg/kg/day, both divided q 12 hours for one week, followed by a second week of placebo (N=5), or (2) placebo first, followed by diuretics (N=5). Patients received Enfamil 20 cal/oz (67 cal/100 ml) approximately 165 ml/kg/day.
Outcomes	Main outcome: pulmonary mechanics Secondary outcome: fluid and mineral handling, renal function
Notes	The authors reported data on fluids and electrolytes, as well as pulmonary function tests on day 6 and on day 7, respectively, of administration of drug 1 and drug 2. The authors measured thoracic gas volume and airway resistance by plethysmography and dynamic compliance using an esophageal balloon. They used appropriate statistical methods for two‐period cross‐over trial and non‐parametric analysis for weight gain. There was no period effect and no evidence for carry‐over effect. For meta‐analysis, we pooled data obtained during first exposure and those obtained after cross‐over.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomized clinical trial with cross‐over design; data during first exposure kept separate from those after cross‐over. The code of randomization was compiled using a table of randomly assorted digits.
Allocation concealment (selection bias)	Low risk	Blinding of randomization: yes
Blinding (performance bias and detection bias) All outcomes	Low risk	Blinding of intervention: yes. Diuretics and placebo were each labeled using a code ("drug 1" or "drug 2"), the identity of which was unknown to nurses who administered the drugs. Blinding of outcome: yes
Incomplete outcome data (attrition bias) All outcomes	Low risk	Complete follow up: yes