开始时间是患者登记时间，结束时间是最后一名受试者接受检查的时间。按这个定义，丹麦试验迄今为止一例手术都没做。
http://prsinfo.clinicaltrials.gov/definitions.html#StartDate
Study Start Date
Date that enrollment to the protocol begins.

Primary Completion Date
the date that the final subject was examined or received an intervention for the purposes of final collection of data for the primary outcome

Study Completion Date
Final date on which data was (or is expected to be) collected