Although most schools will say that the required essay question to be completed during the interview requires no prior research, I would tend to disagree in a sense that it couldn't hurt your chances to be prepared by reading topics related to current events, health care news, ethics, politics, etc. The purpose for requiring the applicant to write the essay during the interview period is to make sure that 1) you're the one who wrote the personal statement, 2) that you're a logical thinker, 3) information that they could ask you to further elaborate during the actual interview.
For example, you may be required to write a one page essay that elaborates on a characteristic trait about professionalism such as "humility." I believe it would be better to have some background information on professionalism beforehand, so that you don't have to waste too much time having to think about what to write.
