Zhang J, Gao X, Han Y, et al. Treatment effects of systematic two-stent and provisional stenting techniques in patients with complex coronary bifurcation lesions: rationale and design of a prospective, randomised and multicentre DEFINITION II trial. BMJ Open 2018;8:e020019. doi: 10.1136/bmjopen-2017-020019.
The sample size estimation in Statistical Analysis Part should be:
From previous studies, we hypothesized that the rate of a 1-year TLF would be 7% in the systematic two-stent technique group and 14% in the provisional stenting group. Accordingly, a total sample size of 600 is needed to detect a power of 0.8 (Type Ⅱ error = 0.2, = 0.05, 2-tailed). Because of the considerable uncertainty, the enrolment is extended to 660 patients (10% increment).
Instead of:
From previous studies, we hypothesized that the rate of a 1-year TLF would be 15% in the systematic two-stent technique group and 25% in the provisional stenting group. Accordingly, a total sample size of 600 is needed to detect a power of 0.8 (Type Ⅱ error = 0.2, = 0.05, 2-tailed). Because of the considerable uncertainty, the enrolment is extended to 660 patients (10% increment).