The percentage of patients failing to complete a study.

Are patients treated equally and comparable apart from the intervention group?

How many patients dropped out during the study?

What is the dropout rate?

Are the losses equally distributed and do they have similar characteristics?

How many patients completed all the evaluations?

How many patients crossed over during the study?

Is there a flow diagram reporting the quantity of patients eligible and included in the study, the number of subjects in each treatment arm, and how the study ended, by presenting the number and the reasons why patients left the study at various points in time?