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Table 3 Sample size calculation

From: Colorectal liver metastases: surgery versus thermal ablation (COLLISION) – a phase III single-blind prospective randomized controlled trial

Significance level (α) 0.05
Power (1-β) 0.80
Hazard Ratio (HR), θ (non-inferiority margin) 1.3
Null-Hypothesis Hazard Ratio, θ0 1.0
Recruitment time/study accrual (months) 36
Follow-up time (months) 60
Ratio control vs. experimental: m2/m1 1.0
Total sample size (NS)/total number to be randomized (NR) 599
Accounting for 3% loss to follow-up after randomization (NLTFU) 18
Accounting for 10% drop-out ratio pre-randomization (NDO) 69
Initial pre-randomization sample size – number of included patients (NI) 687