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Table 4 Displaced fractures: estimated study power for 500 patients per treatment arm (N = 1,000)

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% 40%x
20% 12.0% 22.1% 36.3% 53.2% 70.1% 93.0%
25% 14.5% 27.6% 45.3% 64.5% 81.0% 97.5%
30% 17.2% 33.5% 45.3% 74.4% 88.9% 99.2%
35% 20.3% 40.0% 63.2% 82.7% 94.1% 99.8%
40% 23.8% 47.0% 71.7% 89.2% 97.2% 100.0%
  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.