Lost to follow up
With the term Lost to follow-up ( German lost to follow-up ) is the medical statistics described the phenomenon that the participants of a scientific study of observation are not by scientists more available because the contact between the participants and scientists canceled has been. The reasons for this can e.g. B. moving to another city or the death of the study participant. It is entirely possible that the study participant marked as lost to follow-up has completed the actual study phase and simply did not appear for the follow-up appointments.
Examples
- Example: A smoker takes part in a study in which the effectiveness of an investigational drug is to be investigated, which supports nicotine cessation. During the actual study phase, which lasts half a year, the study participant is given the preparation once a day and actually manages to quit smoking during this period. After a year, the researchers would like to know whether the study participant is still “smoke-free”. To do this, they would like to ask them to introduce themselves again to the test center. However, this is no longer possible because the study participant moved to another city without giving the study team her new contact details.
Therefore, strictly speaking, the term lost to follow-up must be distinguished from so-called drop-outs . In medical jargon, study participants who leave the study during the actual study phase are usually referred to as drop-outs.
- Example: A smoker takes part in a study to investigate the effectiveness of a preparation that supports nicotine cessation. As part of the actual study phase, which lasts six months, the study participant is given the test preparation once a day. After three months, she found out that she was pregnant. She immediately discontinues the investigational product and is excluded from the study by the responsible investigator, since the investigational product could harm the unborn child.
Research practice
In practice, however, this distinction can sometimes be difficult, since - depending on the type of study involved - there can be overlaps between the two terms drop-outs and lost to follow-up. So z. For example, in an observational study that looks at the long-term effects of maternal nicotine consumption on the general health development of the child and whose observation period is designed to span several decades, all those study participants who no longer take part in the study over the years, both as Drop-outs are shown as lost to follow-up as well. For this reason, all study participants whose data were not taken into account in the analysis are sometimes referred to as lost to follow-up or also as drop-outs in the specialist literature . In individual cases, this must be defined in the respective final study report.
See also
literature
- Angelika Caputo, Erika Graf: Planning a clinical study: How many patients are necessary? In: Martin Schumacher, Gabi Schulgen: Methodology of clinical studies. Methodological basics of planning, implementation and evaluation. Second, revised and expanded edition. Springer-Verlag, Berlin a. a. 2007, ISBN 978-3-540-36989-9 .