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Table 2 Estimated study power for 750 patients per treatment arm (N = 1500)

From: Fixation using alternative implants for the treatment of hip fractures (FAITH): design and rationale for a multi-centre randomized trial comparing sliding hip screws and cancellous screws on revision surgery rates and quality of life in the treatment of femoral neck fractures

Baseline risk
(Year 1)^ Relative risk reduction
  10% 15% 20% 25% 30%
20% 15.9% 30.8% 50.5% 70.5% 86.1%
25% 19.6% 38.7% 61.6% 81.5% 93.5%
30% 23.6% 46.8% 71.7% 89.3% 97.4%
35% 28.2% 55.2% 80.3% 94.5% 99.1%
40% 33.3% 63.6% 87.3% 97.5% 99.7%
  1. *Number of patients per treatment arm, alpha = 0.05.
  2. ^Year 2 risk is 1/3 that of year 1.
  3. Bold numbers indicate statistical power range for this study.