Table 5.

Survey of trial investigators with non-registered studies as of April 2020

Topic	36 of 60 investigators filled out the questionnaire, 24 did not respond
General awareness of Researchers	Prospective registration is required by law	Registration is required before first participant enters the study	Swiss National Clinical Trials Portal (SNCTP)a is not a primary registry	Registration is reasonable
	27 (75.0%)	26 (72.2%)	14 (38.9%)	32 (88.9%)
Study support by service team	Clinical Trials Unit	Contract Research Organisation	Others	No support service
	7 (19.4%)	3 (8.3%)	2 (5.6%)	24 (66.7%)
Knowledge of primary registries	ClinicalTrials.gov	German Clinical Trials Register (DRKS)	EU Clinical Trials Register (EUCTR)	ISRCTN-Register
	32 (88.9%)	13 (36.1%)	14 (38.9%)	7 (19.4%)
Perceived Barriers to study registration	Insufficient knowledge of primary registries/ registration processes:	Limited time/ resources for registration process	Missing reminder of obligation to register the study	Othersb
	8 (22.2%)	18 (50.0%)	13 (36.1%)	6 (16.7%)
Stated reasons for non-registration	- Study postponed/ unclear study start date (n = 2) - Missing local SOPs for registration (n = 1) - Unclear interpretation of regulations for Phase I studies (n = 1) - Study not considered as clinical trial by investigator (n = 4) - Unaware of the obligation to register (n = 2) - Short study, retrospective registration considered as unnecessary/confusing (n = 1) - One researcher responsible for all registrations in the research institute (n = 1) - No reason specified (n = 24)

Abbreviations: ISRCTN International Standard Randomized Controlled Trial Number, SOP Standard Operating Procedure

^aIn Switzerland every study approved by an ethics committee and registered in a primary registry will be listed on the Swiss National Clinical Trials Portal (SNCTP)

^bOthers included unclear definition of the study, unclear responsibilities for registration within institution, COVID-19 induced delay