"Minimal risk" associated with a clinical trial may have different meanings based on different perspectives. Westra et al listed criteria for minimal risk relevant to clinical trials involving children. The authors are from Leiden University and Erasmus Medical Centre I The Netherlands.


Risk may take the form of:

(1) discomfort to the patient

(2) harm


Determination of risk is based on empirical data, expert opinion and/or procedural characteristics.


Each risk can be defined based on:

(1) the magnitude of an outcome (minimal to severe)

(2) the likelihood


Minimal harm for discomfort was defined as:

(1) considerable discomfort no more than 1 in 4 (25%)


Minimal risk involving harm was defined as:

(1) the risk of small harm is < 1 in 100 (1%)

(2) the risk of moderate harm is < 1 in 10,000 (0.01%)

(3) the risk of serious harm is < 1 in 1,000,000 (0.0001%)


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