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Table 2 Statistical power for a trial sample size of 4000 with 1:1 randomization to vitamin D3 and placebo arms, a nominal Type I error rate (alpha) of 0.05 and a 10% loss to follow-up rate

From: Efficacy of vitamin D3 supplementation in reducing incidence of pulmonary tuberculosis and mortality among HIV-infected Tanzanian adults initiating antiretroviral therapy: study protocol for a randomized controlled trial

Mortality

 

Relative risk of mortality

 Cumulative 1-year incidence mortality in placebo arm

RR = 0.75

RR = 0.70

RR = 0.65

  10%

76%

90%

97%

  12.5%

85%

95%

99%

  15%

91%

98%

99%

Pulmonary tuberculosis (TB)

 

Relative risk of pulmonary TB

 Cumulative incidence pulmonary TB in placebo arm

RR = 0.70

RR = 0.65

RR = 0.60

  5%

61%

75%

86%

  7.5%

79%

90%

97%

  10%

90%

97%

99%