While Vivus registered four Stage III clinical trials with the government registry, no study results from any of those trials have been published, though presumably preliminary data were submitted to the FDA panel.

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Second, by including the entire eligible Danish population, which is covered by a national tumor registry, the study avoids the problem of selection bias (that is, people who do not make it into your study for various reasons, including refusal).

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HeartWare said that the FDA was requiring the company to perform a post-approval study in the form of a registry consisting of 600 HeartWare patients and an additional 600 control patients.

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