Non pre-appraised research, or original clinical studies, can be strong sources of evidence when practice guidelines & systematic reviews are not available. Also, practice guidelines can get out of date fairly quickly, so reading newly published studies can provide you with more up-to-date information. High-quality, rigorous, original studies may include (but aren't restricted to) randomized control trials (RCTs), cohort studies, and case-controlled studies. Key sources of pre-appraised research include:
Both PubMed & CINAHL have a tool that allows you to search for studies that may best address your research question. This is called the Clinical Queries filter. You can set up your search to find studies that address the following types of questions: Therapy (intervention), Etiology, Diagnosis, and Prognosis.
Here is an example of how you can set up a search in PubMED to retrieve articles that address treatment or interventions: