Читать книгу Evidence in Medicine - Iain K. Crombie - Страница 30

The impact of loss to follow‐up is difficult to predict. A review found that loss to follow‐up was sometimes higher in the treatment group and sometimes in the comparator [47]. Possibly the effect of loss to follow‐up depends on the specific trial characteristics, such as the illness being treated or the acceptability of the treatment to patients. Whatever the explanation, concern remains that some trials may be biased due to patient attrition.