You are correct that this is something that should come up at audit, as it is frequently cited in inspections findings.>>
It is a good idea to look at the RQA GCP Q&As on this website. See Question - "Who should be listed on the delegation of responsibilities log?">>
Is this a question of definitions?>>
ICH E6 1.56 defines Subinvestigator:- "Any individual member of the clinical trial team designated and supervised by the investigator at a trial site to perform critical trial-related procedures and/or to make important trial-related decisions (e.g., associates, residents, research fellows)". So it is best to ask the question the other way round; which individual members of the clinical trial team (designated and supervised by the investigator at a trial site) perform critical trial-related procedures and/or to make important trial-related decisions? These are sub-investigators and should be listed on the delegation log (ICH E6 4.1.5).>>
Unfortunately it has occasionally become practice to suggest that only physicians can be sub-investigators. This is not true. It is sometimes the case that sites in the USA might be more prone to listing only physicians as sub-investigators, I'm not aware of any statistics on this. In fact the FDA has cited, in Warning Letters, the fact that individuals (such as study nurses, study coordinators, etc) were not listed on the delegation log despite performing important trial related duties. EU inspectors have often made inspection findings because individuals (such as study nurses, etc) performing important trial related duties, were not listed on the delegation log.>>
It is often the case that the sub-investigator delegation logs do contain more than just physicians, but I am unaware whether this is changing or not. Perhaps other members of RQA might know if there is a growing trend.>>
As you say, many sponsors (& many inspectors) think it is inappropriate to complete 1572 forms for European investigator sites. You should look at the FDA guidance on completing the 1572 - Information Sheet Guidance for Sponsors, Clinical Investigators, and IRBs Frequently Asked Questions – Statement of Investigator (Form FDA 1572) May 2010. -- "The decision to list an individual in Section #6 depends on his/her level of responsibility (i.e., whether he/she is performing significant clinical investigation-related duties). In general, if an individual is directly involved in the performance of procedures required by the protocol, and the collection of data, that person should be listed on the 1572. .... It is not necessary to include in this section a person with only an occasional role in the conduct of the research, e.g., an on-call physician who temporarily dealt with a possible adverse effect or a temporary substitute for any research staff (see ICH E3, Section 6)"