As well as using systematic reviews, we look for qualitative studies. This type of study helps us understand what it's like for people to live with a certain disease, and what it's like for people who are close to them. Qualitative information is collected, for instance in interviews, and then analyzed.
To stay up-to-date, we usually only include systematic reviews that are no more than three years old. This is important because medical knowledge grows rapidly: Every year the results of thousands of clinical studies are published around the world.