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However, in certain circumstances, a per‐protocol summary of the trial results may be more relevant. In such an analysis, the comparison is made only in those patients who comply (which has to be carefully defined in advance) with the treatment allocated. One example of a per‐protocol analysis is if the toxicity and/or side effects profile of a new agent are to be compared. In this circumstance, an ITT analysis including those patients who were randomised to the drug but then did not receive it (for whatever reason) could seriously underestimate the true scale of the relative safety profiles. If a per‐protocol analysis is appropriate for such endpoints, then the trial protocol should state that such an analysis is intended from the onset. One situation where a per‐protocol analysis is important is when reporting the results of non‐inferiority trials that we discuss in Chapter 15.