Length of Follow-Up

The duration of follow-up, which is the time that contact is maintained with study participants so that information can be collected to determine the effects of a given intervention, is a fundamental and important part of surgical trials. Appropriate follow-up is determined during trial design. Failure to determine adequate follow-up period can compromise the validity of a study and introduce bias. However, given the relative scarcity of resources such as money, personnel, and facilities available to research teams, determining the optimal length of follow-up can be difficult. Additionally, an adequate percentage of follow-up is also necessary to ensure valid results, and failure to do so can limit the ability to draw meaningful conclusions, which comprises the ethical responsibility of the study team. To achieve an optimal balance, determination of primary and secondary outcomes of interest is necessary. Once outcomes are determined, an appropriate follow-up should be set to accurately capture the occurrences of each outcome of interest. Although it is ideal to determine follow-up prior to initiation of a study, sometimes it is necessary to extend the length of follow-up using post-trial follow-up. To illustrate these concepts, several examples from trials on outcomes following double-bundle ACL reconstruction are presented.