Managing withdrawals and exclusions of study participants in COVID-19-research by NUKLEUS.

Background: This article describes how withdrawals and exclusions of study participants can be managed in COVID-19-cohort studies by NUKLEUS (German: NUM Klinische Epidemiologie- und Studienplattform), using NAPKON (German: Nationales Pandemie Kohorten Netz). The aim of this manuscript was to describe, how partial withdrawals can be performed so that most of the data and bio-samples can be kept for research purposes.

Methods: The study has taken all signed informed consents (ICs) of study participants into account in order to develop a method how partial withdrawals can be developed and installed. The informed consents, which comprise of mandatory and optional modules were investigated to find out which optional modules can be withdrawn from without withdrawing consent from the whole study.

Results: Withdrawals refer to signed ICs including mandatory and optional modules. Withdrawals can be submitted verbally or in writing, and regarding the IC, as a whole, or only partially. Consequently, implemented withdrawals for NAPKON cohorts comprise partial withdrawals with partial or no data deletion or complete withdrawals with data deletion. Thus, more data is still available for research purpose, which would have been lost without the possibility of partial withdrawals. In NAPKON, a total of 3,97% of the participants have submitted a withdrawal or have been excluded from the study if the inclusion criteria were no longer met.

Conclusions: This manuscript is to the author's knowledge one of the first article related to withdrawals within COVID-19-studies (NAPKON). The processes serve as 'best practice' examples for planning and establishing withdrawal processes in medical research.