Cattarelli 2006.

Methods	Blinding of randomization: yes. Randomization was done by computer. Blinding of intervention: yes. Theophylline or placebo was prepared by a doctor from the neonatology section, not involved in patient care, using syringes with identical appearance. Complete follow‐up: yes. Blindness of outcome: yes. The medical and nursing staff were blinded to the patient assignment.
Participants	Of 54 eligible patients, 50 were entered into the study and randomly allocated to placebo or to theophylline. Entry criteria: Inborn preterm neonates <= 32 weeks gestational age, RDS within 6 hours of life, needing mechanical ventilation or nasal continuous positive airway pressure. Exclusion criteria: kidney and/or urinary tract congenital abnormalities, congenital heart defects, prenatal exposure to inhibitors of angiotensin converting enzyme or non‐steroidal anti‐inflammatory drugs (NSAIDs), and chromosomal disorders or multiple malformations. Patients assigned to placebo (n=25) had an average gestational age of 28.7±1.6 weeks and a birthweight of 1157±354 g. Patients assigned to theophylline (n=25) had an average gestational age of 28.7±2.0 weeks and an average birthweight of 1192±378 g.
Interventions	Patients in the treatment group were allocated to receive i.v. theophylline 1 mg/kg daily; controls were allocated to receive an equal volume of placebo (5% dextrose in water) for three days. The first dose was given soon after it had been confirmed that inclusion criteria had been met.
Outcomes	Death, BPD, Death or BPD, PDA, IVH, severe IVH, oligoanuria (urine output <1 ml per kg per hour) , serial measurements of urine output, serial serum creatinine values, blood urea nitrogen, hyponatremia, hyperkalemia, periventricular leukomalacia, retinopathy of prematurity, necrotizing enterocolitis, length of stay.
Notes	Several infants received other medications that could affect outcomes of interest in this review. Eight infants in the theophylline group and twelve in the control group received furosemide, 21 in each group received dopamine, nine in the theophylline group and twelve controls received dobutamine, six in the theophylline group and four controls received ibuprofen, one control received indomethacin, and eight in the theophylline group and nine controls received caffeine.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomization was done by computer
Allocation concealment (selection bias)	Low risk	Blinding of randomization: yes
Blinding (performance bias and detection bias) All outcomes	Low risk	Blinding of intervention: yes. Theophylline or placebo was prepared by a doctor from the neonatology section, not involved in patient care, using syringes with identical appearance. Blindness of outcome: yes. The medical and nursing staff were blinded to the patient assignment.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Complete follow‐up: yes