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Table 4 Reported rates of participant flow through the trial as a percentage of the number required by the reported sample size calculation

From: A review of reporting of participant recruitment and retention in RCTs in six major journals

 

Number of studiesa

Median % of sample size required

First and third quartiles

Minimum and maximum

Invited to screening

12

410%

288%, 951%

131%, 2549%

Attend screening

62

230%

132%, 379%

83%, 2361%

Eligible

58

130%

108%, 160%

72%, 431%

Randomised

106

110%

100%, 128%

43%, 213%

Outcome assessed

94

100%

92%, 111%

36%, 158%

In analysis

102

103%

98%, 117%

43%, 169%

  1. 7 studies which stopped early having demonstrated a benefit of treatment are excluded from these analyses
  2. a Relates to the number of studies providing relevant data
  3. Note: the α (significance) and 1-β (power) levels used in each trial's sample size calculation may vary
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ISSN: 1745-6215