What types of studies will help you answer your question? Remember, you want to know:
Ideally, you’d only include studies at the top of the hierarchy of evidence. Of those, which fit the needs of your systematic review?
Randomized Controlled Trials (RCTs): YES
This is the gold standard for research, so you’ll want to use any RCTs that fit our question.
Cohort Studies: YES
These could be useful for information about the long-term safety of each kidney failure intervention.
Case-control studies: Probably not
You’re not looking for the cause of kidney failure. You’re trying to compare two types of treatment.