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Table 1 key terminology and calculations

From: Early warnings and repayment plans: novel trial management methods for monitoring and managing data return rates in a multi-centre phase III randomised controlled trial with paper Case Report Forms

Terma Definition
Case Report Form due date Date of the event that a form is linked to. For example, for a 6-month post-randomisation follow-up visit, a follow-up form due date would be the date of randomisation plus 6 months
Tolerance period Short period after the due date (e.g. 14 or 28 days) for the participating centre to complete and return the relevant Case Report Forms. Forms are not considered overdue until this period has passed
Scheduled Form due date is in the future
Expected Form due date has passed, but the tolerance period has not. For the purposes of calculating the data return rate, these are counted as not due yet (the same as Scheduled forms)
Received Form has been received and entered into the trial database system
Overdue The tolerance period has passed, but the form has not yet been received at the clinical trials unit
Unobtainable Participating centre has confirmed that data are not available and no form will be sentb
Data return rate (overall) \( \frac{Received}{Received+ Overdue+ Unobtainable} \)
Date return rate (excluding unobtainable forms)c \( \frac{Received}{Received+ Overdue} \)
  1. aForm statuses (Scheduled, Expected, Received, Overdue, Unobtainable) are mutually exclusive categories
  2. bForms are designated Unobtainable to mean no further requests for the data will be made. These forms can either be included in data return rate statistics (as permanently missing) or excluded
  3. cExcluding Unobtainable forms can be useful for looking only at unresolved problems, and excluding historical issues that cannot be resolved retrospectively such as missed patient-reported outcomes