学习了，非常感谢，恩恩

A matched-cohort study was performed to define the risk factors for BSI in patients with HNC. Cases were defined as hospitalized patients prospectively diagnosed with BSI during the study period. Potential controls were recruited from a cohort of hospitalized patients with HNC who did not have a BSI during the study period.

Controls were selected randomly from the cohort of hospitalized patients, and matched by age (+/- 3 years) and the closest date of admission. Cases and controls were not matched in any other way, but two controls were selected per case. 

文中读到这段话，个人感觉这个是有问题的，请问这个应该叫做 case-control study 而不是 cohort study对吗？求大侠回答！