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Logo of bmcmrmBioMed Centralsearchsubmit a manuscriptregisterthis articleBMC Medical Research Methodology
Published online 2012 April 17. doi: 10.1186/1471-2288-12-50

Table 5

Hypothetical examples of sample size requirements for RCTs of injurious falls prevention by risk group

OutcomeIncidence in study populationRequired sample size
Low risk (25% lower than intermediate risk)
≥ 1 injurious falls15.00%7408
≥ 1 fractures3.75%33222
≥ 1 hip fractures2.25%56168
Intermediate risk
≥ 1 injurious falls20.00%5258
≥ 1 fractures5.00%24618
≥ 1 hip fractures3.00%41828
High risk (25% higher than intermediate risk)
≥ 1 injurious falls25.00%3966
≥ 1 fractures6.25%19456
≥ 1 hip fractures3.75%33222

Assumptions for sample size calculation: effect size -15% with respect to all outcomes, statistical power 80%, significance-level 5%, two-sided tests, not adjusted for multiple testing.

1Fallers reflect those study participants who experience any fall (injurious or not injurious) during the study period