Clinical Trials 

In MEDLINE, articles reporting the results of clinical trials and clinical studies are usually tagged with one of the following publication types

• clinical trial
• clinical trial, phase i
• clinical trial, phase ii
• clinical trial, phase iii
• clinical trial, phase iv
• comparative study
• controlled clinical trial
• evaluation studies
• multicenter study
• randomized controlled trial
• twin study
• validation studies

In PubMed, you can limit your search to one of these publication types by clicking the "Limits" tab, scrolling down to the "Type of Article" box, selecting the publication types of interest, and hitting the "Go" button.

In EBSCOhost MEDLINE, you can limit your search to one or more of these publication types by clicking the "search options" link (right-hand side of the screen), scrolling down to the "Publication Types" box, holding down the "Ctrl" key while you select publication types of interest, and hitting the "Search" button. 

In CINAHL articles reporting the results of clinical trials are usually tagged with the "Clinical Trial" publication type.  To limit your search to the "Clinical Trial" publication type, click the "search options" link (right-hand side of the screen), scroll down to the "Publication Type" box, holding down the "Ctrl" key while you select publication types of interest, and hit the "Search" button. 

In PsycINFO articles reporting results of clinical studies and trials are usually tagged with one of the following methodologies:

• Clinical Case Study
• Empirical Study
• Experimental Replication
• Followup Study
• Longitudinal Study
• Prospective Study
• Retrospective Study
• Field Study
• Qualitative Study
• Treatment Outcome/Clinical Trial

To limit your search to one or more of these methodologies, click the "search options" link (right-hand side of the screen), scroll down to the "Methodologies" box, hold down the "Ctrl" key while you select methodologies of interest, and hit the "Search" button.