SEARCHING THE LITERATURE “Seventy-five trials and eleven systematic reviews a day: how will we ever keep up?” Bastian H, Glasziou P, Chalmers I. PLoS Med 2010 1. Background questions are general questions, usually of etiology, pathophysiology and prognosis of disease. Example: “What causes carpal tunnel syndrome?”, “Why is there no edema in patients with SIADH?” 2. Foreground questions are more specific questions, usually of diagnosis, harm and therapy but also of etiology or prognosis. Example: “Does use of B-complex vitamins reduce pain and numbness in patients with carpal tunnel syndrome?” 3. Defining the Patient, Intervention in question and possible Outcomes may help in formulating a foreground clinical question: “Does use of B-complex vitamins (intervention) reduce pain and numbness (outcomes) in patients with carpal tunnel syndrome?” 4. When performing literature search for a foreground question it may be helpful to consider whether you anticipate to find few or numerous studies. If multiple studies are expected it will be more efficient to search for a systematic review (for one intervention) or evidence synthesis (for multiple interventions). If few studies are expected on the topic, one may have to search for the original studies in MEDLINE, primary journals or abstracts of those studies in secondary journals or pre-appraised sources. Clinical Dilemma Foreground Background question question Many studies Few studies likely Narrative reviews likely available available (Textbooks, Journals, UpToDate) Look for systematic Look for original studies: reviews or synthesis of evidence: Clinical Evidence 1. Appraised: ACP Journal Club, Journal Watch, UpToDate Essential Evidence plus TRIP database PIER modules 2. Unfiltered: MEDLINE, Cochrane database Primary Journals BMJ Clinical Evidence, ACP PIER modules and UpToDate provide summaries of evidence categorized by disease/disorder. This allows one to search for the evidence on multiple interventions (screening, diagnosis, therapy etc) regarding the same disorder. The uptake of the most recent studies by these resources may not be immediate, so searching for individual trials may still be necessary. Clinical Evidence categorizes the interventions as beneficial, likely to be beneficial, trade off between benefits and harms, unlikely to be beneficial, likely to be ineffective or harmful and unknown effectiveness. This is based on their assesment of available evidence. UpToDate uses the GRADE system to rate the quality of evidence and provide recommendations: Recommendation Quality of Evidence Grade 1: Strong (most patients will A: High-quality (multiple high quality benefit) RCTs or systematic reviews) Grade 2: Weak (balance of benefits B: Moderate-quality (RCTs with and harm close or uncertain) limitations or high quality observational studies) C: Low-quality (poor quality observational data, expert opinion or RCTs with major flaws) The Cochrane database provides among others, systematic reviews prepared by the Cochrane Collaboration (Cochrane Database of Systematic Reviews-CDSR), systematic reviews prepared by others (Database of Abstracts of Reviews of Effects-DARE) and a large database of RCTs (Cochrane Central Register of Controlled Trials-CENTRAL). TRIP database allows search for all levels of evidence (synopses, systematic reviews, pre-appraised and original studies). It also provides a filter to enable search for only high quality evidence. ACP Journal Club provides structured abstracts of original studies along with expert commentary. MEDLINE is a vast but relatively unfiltered source of original studies but also of systematic reviews, practice guidelines etc.
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