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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.
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Trials

ISSN: 1745-6215