Has someone already done this?

It would be embarrassing, and an incredible waste of time, if you conducted a systematic review after someone else had already done the same research. For example, there are at least 20 systematic reviews studying whether the chemicals doctors use in imaging tests like MRIs and PET scans can lead to kidney damage.

Even if no one has addressed your specific question, you can learn a lot from systematic reviews that are related to your research interest.

That’s why you should always check if your topic has already been addressed by a systematic review or if a similar systematic review is already underway.