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Table 7 APTS: Delayed cord clamping

From: Heterogeneity in pragmatic randomised trials: sources and management

Patients: Fetuses from women expected to deliver before 30 weeks of gestation

Centres: 25 centres in seven countries

Intervention: Delayed cord clamping

Control: Immediate cord clamping

Outcome: Composite outcome of death or major morbidity

Design: Two parallel-group individually randomised trial

Sample size calculation: non-adherence

“The original sample was 1600 infants, yielding 90% power (two-sided P = 0.05) to detect an absolute difference in the incidence of the primary outcome of 8 percentage points between the two groups (30% in the immediate-clamping group vs. 22% in the delayed-clamping group; relative difference, 27%), with the assumption of 10% nonadherence. If the rate of nonadherence to the Intervention and loss to follow-up reached 20%, there was more than 80% power to detect this difference.”

Subgroup analysis

“Tests for interaction were used to detect heterogeneity for the primary outcome in three prespecified subgroups: gestational age (<27 weeks vs. ≥27 weeks), sex, and method of delivery (cesarean section vs. vaginal delivery).”