SYSTEMATIC REVIEWS:THEORY AND PRACTICESearching for the Literature

By the end of this class, you will be able to:• Build a searchable question and piece out its main ideas• Understand the complexity and time-intensive nature of

researching for a systematic review• Build a list of search terms, including synonyms• Build a search appropriate for a keyword database• Build a search appropriate for a controlled vocabulary

database• Import references into a citation management program

Follow Along• http://researchguides.library.tufts.edu/nutr369• Download slides from first page of the guide

What is a Systematic Review?

"A systematic review attempts to collate all empirical evidence that fits pre-specified eligibility criteria to answer a specific research question. It uses explicit, systematic

methods that are selected to minimize bias, thus providing reliable findings from which conclusions can be drawn and

decisions made. Meta-analysis is the use of statistical methods to summarize and combine the results of

independent studies." - Cochrane Collaboration

Evidence Pyramid

Best Evidence

Synthesized & Evaluated Literature

Primary Literature

May or May not be Evidence-Based

Provided by HealthLinks, University of Washington, http://healthlinks.washington.edu/ebp/ebptools.html

Why are there so few systematic reviews?

• Have the most evidence to support their conclusions• Less abundant in the literature

• Time• Effort

• Most relevant for decision-making

Top of the Pyramid Resources

How do I find them?• Search MEDLINE for systematic reviews, meta-analyses or individual study types e.g. RCTs• Search databases specific to your subject for reviews that include a search methodology

The EBM Cycle1. Assess the patient: A clinical question arises from caring for a patient.

2. Ask the question: Construct a well-built foreground question derived from the case.

3. Acquire the evidence: Find the answer from the evidence presented in the medical literature and identify the best resource from among the many.

4. Appraise the evidence: Appraisal includes validity (closeness to truth) and applicability (usefulness in clinical practice).

5. Apply: Communicate the evidence to your patient and integrate the evidence with clinical expertise, patient preference and apply.

6. Self-evaluation: Evaluate the process and outcome.

Creating a Searchable Question• The first step is to state your topic in a detailed question• Next, you need to break that question down into the different ideas

(typically the nouns, sometimes the verbs)• Example:

Does exercise improve diabetes?

• Are the outcomes measurable?• Is the question specific enough?

Idea 1 Idea 2 Idea 3

Decide Resources to Search• Subject-specific? Date ranges of database? Keyword or

controlled vocabulary?• Different databases require different search strategies &

formulas• Keyword databases like Google require synonyms and more complex

search formulas to be comprehensive• Multiple terms to capture different ways of stating same/similar ideas

• If the database has it’s own thesaurus, you can usually do a comprehensive search more simply• Concept searching v. keywords

• Some database recognize more commands and symbols than others

Keyword Database Searching• Remember: Computers are dumb (but fast).• You will need to think of a list of synonyms for each

separate idea• Your job to think like all the different authors and search for the

way they may have expressed the idea

• Computers understand the world via math, so just like math you have operators and order of operations to deal with• AND, OR, NOT• “quotes” and (parenthesis)• Sometimes truncation symbols (* or $)

Controlled-Vocabulary Searching• “… a carefully � selected list of words and phrases,

which are used to tag units of information (document or work) so that they may be more easily retrieved by a search…Controlled vocabularies reduce ambiguity inherent in normal human languages where the same concept can be given different names and ensure consistency.” –Wikipedia• Boolean operators still useful• Need to combine controlled terms with keywords

Stay Organized• Interlibrary loan

• Time• Money

• Vocabulary lists• Search strategies• # results, # of exclusions, date of searches, etc.• Citation management

• Many options• Help you store and organize citations• Share citations among a group• Format citations for publication

PRACTICE