Try adding another parameter - Focus your question
population, location, age group, specific medication, etc.
Try limiting your search to only titles and abstracts instead of looking at all terms
Ask your helpful librarian for assistance!
Searching is an iterative process. There is no real "right way" to search. It is very much trial and error. Try something. If it doesn't work, try something else. When you find something that works, build on it. If you need help, reach out.