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Table 4B Required sample size to test all secondary hypotheses in main study.

From: The effects of organic nitrates on osteoporosis: a randomized controlled trial [ISRCTN94484747]

Hypothesis Clinically Important Difference Standard Deviation of Change Subjects, per group
Hip BMD will be higher in treatment group* 2% 4.5% (5, 59, 62, 80, 81) 107
NTx will lower in treatment group† 15% (69, 87–89) 28% (30, 35) 105
BSAP will be higher in treatment group† 15% (69, 87–89) 25% (30) 105
Headaches due to nitrates will be higher in treatment group** 20% (30) 5% (30) 36
Trabecular bone density by pQCT will be higher in treatment group** 10 mg/cm3 (67, 70) 7.5 mg/cm3 (67, 70) 31
  1. * Based on a t-test, assuming a two sided alpha of 0.05 a power of 0.90 and a standard deviation of change in BMD measurements of 4.5%.
  2. † Assuming a repeated measures analysis of variance (75).
  3. ** Based on a Student's t test, assuming a two sided alpha of 0.05, a power of 0.90.