Haynes has developed a hierarchy of resource types to help select relevant evidence searching resources. The resources highest in the pyramid have the greatest synthesis of the evidence, minimise bias and are the best time-savers; those in the lowest level contain the primary studies, the most detail and the most recent information available.
Begin searches with resources high in the hierarchy. If you do not find the clinical answer that you seek, move down levels until you find the appropriate evidence. Not every question can be answered with every resource, and you may need to search for primary studies using standard databases such as MEDLINE Complete.
Read more on Haynes' hierarchies:
Haynes RB: Accessing pre-appraised evidence: fine-tuning the 5S model into a 6S model. Evidence Based Nursing 2009; 12: 99-101 doi:10.1136/ebn.12.4.99-b
Haynes RB: Of studies, syntheses, synopses, and systems: the "4S" evolution of services for finding current best evidence. Evidence Based Medicine 2001; 6: 36-39 doi:10.1136/ebm.6.2.36
Haynes RB: Of studies, syntheses, synopses, summaries, and systems: the "5S" evolution of information services for evidence-based healthcare decisions. Evidence Based Medicine 2006; 11: 162-164.
Guidelines are summaries of available evidence, with Australian guidelines usually endorsed by an official body such as the NHMRC or one of the Royal Australasian Colleges. They usually provide an indication of which actions to take in particular conditions.
UK Guidelines site is now split between 2 sites:
Summaries are generally the highest, most readily available Evidence Based Practice resources. They summarise the best available evidence-based information about specific clinical problems, and are regularly updated with exhaustive literature searches. When there is no evidence in this level to answer your specific clinical question, move to a search in synopses resources.
Point of care tools are good summaries, and are designed to be searched and read quickly. These include:
Primary studies and clinical trials form the basis of the synthesised, filtered sources. It is still important to be able to access these in order to check the accuracy of the filtered sources, to find out whether there are newer studies not yet covered by the filtered sources, and for when your clinical question can't be answered by the filtered sources.
See also other biomedical databases.
Different questions are best answered by different study types. Intervention or therapy type questions are best answered by Randomised Controlled Trials (RCTs), whereas diagnostic questions are best answered by cohort studies.
PubMedhas a clinical queries search which filters for the most relevant study type for your question. You can also choose from Broad (more sensitive - will pick up more) or Narrow (more specific - will be more precise) results sets.