SYSTEMATIC REVIEWS: THEORY AND PRACTICE

Searching 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

Why are there so few systematic reviews?

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

Top of the Pyramid Resources

• Have the most evidence to support their conclusions • Less abundant in the literature • Time • Effort • Most relevant for decision-making 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 Cycle

1.

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?

Idea 1 Idea 2 Idea 3 • Are the outcomes measurable?

• Is the question specific enough?

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

•

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