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Chapter 7
Clinical usefulness was examined by means of decision curve analysis (33). In this analysis, net benefit is calculated as the difference between true positive (i.e., tube placement justified) counts and false positive (i.e., tube placement not-justified) counts, weighted by the relative harm of a false-positive and false-negative result, over a range of threshold probabilities (pt). In the context of the current study, these threshold probabilities indicate the level of risk for long term feeding-tube dependency at which a patient or surgeon would opt for proactive placement. Net benefit can be interpreted as the increase in the proportion of patients receiving the appropriate treatment through use of the prediction model, compared to a situation in which all patients would (or would not) receive the treatment (34).
In a post-hoc secondary analysis, associations between prolonged tube dependency and timing of tube placement during CRT, and neck dissection within 90 days after CRT were assessed univariably.