When deciding on what keywords and search results filters to use , frame your thoughts around:
Evidence Based Medicine (EBM) refers to the process of published literature undergoing additional systematic reviews to ensure accuracy and duplicity since EBM literature is used to make clinical decisions.
The Cochrane group of medical/health professionals initiated the EBM process. The library's Cochrane database is not full text so you will need to use the library's document delivery service(IDS) to obtain fulltext articles.
While searching in Cochrane database, Pubmed database or with GoogleScholar, articles tagged as meta-analysis, systematic reviews are considered better than case reports.