Stats - EBM Levels, Questions, Searching and Grades Of Evidence

Question 1

What are the 7 levels of evidence in the traditional hierarchy system?

Answer 1

1 Systematic reviews and meta-analyses of RCTs with definitive results
2 RCTs with definitive results (confidence intervals that do not overlap the threshold clinically significant effect)
3 RCTs with non-definitive results (a point estimate that suggests a clinically significant effect but with confidence intervals overlapping the threshold for this effect)
4 cohort studies
5 case control
6 cross sectional studies
7 case reports

Question 2

What are the 4 basic steps in Evidence Based Medicine?

Answer 2

1) develop a focused clinical question
2) search for the best evidence
3) critically appraise the evidence
4) apply the evidence and evaluate the outcome

Question 3

In step 1, we should consider background and foreground questions. What do each of these mean?

Answer 3

Background questions are general questions about conditions, illnesses, syndromes and patterns of disease, and pathophysiology (e.g. what are the side effects of statin drugs?).

Foreground questions are more often about issues of care. They query specialised and distinct knowledge needed for specific and relevant clinical decision-making (e.g. does hand washing in healthcare workers reduce hospital acquired infection?)

Question 4

When addressing foreground questions the components of the search question are generally defined using the PICO system.

What is PICO?

Answer 4

Patient (P) What is the patient group of interest?
Intervention (I) What is the intervention of interest?
Comparison (C) What is the comparison?
Outcome (O) What is the primary outcome?

Question 5

In searching for evidence, we have primary and secondary research.

What do each of these mean?

Answer 5

Primary (aka empirical research) - sources that contain the original data and analysis from research studies. No outside evaluation or interpretation is provided (e.g. RCTs, cohort studies, case-control studies, case-series, and conference papers).

Secondary - sources that interpret and analyse primary sources. These sources are one or more steps removed from the event (e.g. evidenced based guidelines and textbooks, meta-analysis and systematic reviews).

Question 6

What are filtered sources?

Answer 6

Filtered resources summarize and appraise evidence from several studies and included systematic reviews, critically appraised topics, evidence-based guidelines and point of care references.

Question 7

What are unfiltered sources?

Answer 7

Unfiltered sources are large databases of articles that have not been pre-screened for quality. The searcher must filter out the results that do not meet their requirements using either specific vocabulary terms of pre-formulated searches or terms by the database.

When trying to answer foreground questions, it if often necessary to search the primary literature for original research articles. In behavioural health, these studies are found in a number of literature databases, including Medline (PubMed), PsycInfo, CINAHL and EMBASE.

This type of search can be quite a challenge. Besides needing to locate and master multiple sources, many of the articles included in these databases are not evidence-based. Special search strategies and techniques are needed to filter through the many references to find patient-centred, systematically researched studies.

Question 8

Which database dates back to the late 1890s. It began with the simple acquisition, cataloguing, and indexing of the literature of the medical sciences?

In 1964 a computer-oriented bibliographic retrieval and publication system was created, called….?

It was launched online in 1971 (accessable worldwide in 90s) and called…?

Answer 8

NLM (National Library of Medicine)

MEDLARS (Medical Literature Analysis and Retrieval System)

MEDLINE

Question 9

How is MEDLINE indexed?

What descriptors are added?

Answer 9

MEDLINE records are usually created from electronic metadata sent by journal publishers to the NLM. However, indexing is still manually added to article entries by staff at the NLM.

This indexing includes basic error checking and the allocation of MeSH (Medical Subject Headings) descriptors to each article based on its content (MeSH terms are descriptors developed by librarians to organize and categorize topics).

Question 10

What is MeSH?

Answer 10

Medical Sub Headings AKA MeSH is the NLMs controlled vocabulary thesaurus that consists of sets of descriptive terms organised in a hierarchical structure that allow searching at various levels of specificity

Question 11

How does PubMed compare to MEDLINE?

Answer 11

There is much confusion about the difference between MEDLINE and PubMed.

PubMed is actually a larger database run by the National Centre for Biotechnology information (NCBI) a sub-section of the NLM, of which MEDLINE is the largest component.

In addition to the Medline subset, PubMed also contains:

1) In progress records (those not yet indexed into Medline)
2) Older records
3) Records considered out the scope of Medline (e.g. general chemistry and non-life science)

Question 12

What is the name of the large European database that overlaps with MEDLINE by approx 30-50%?

How does it compare with Medline?

Answer 12

Embase (Excerpta Medica database)

Compared with Medline, Embase provides a greater coverage of European and non-English language publications. It also covers a broader range of topics concerned with pharmaceuticals, psychiatry, toxicology, and alternative medicine.

Question 13

How many databases make up the Cochrane Library?

Answer 13

6

Question 14

The following is one of the databases that make up the Cochrane Library; what is this and what does it do?

1) CDSR

Answer 14

The Cochrane Database of Systematic Reviews (CDSR) - peer-reviewed systematic reviews prepared by Cochrane Review Groups

Question 15

The following is one of the databases that make up the Cochrane Library; what is this and what does it do?

2) DARE

Answer 15

The Database of Abstracts of Reviews of Effects (DARE) - Contains quality-assessed abstracts of systematic reviews (those reviews not prepared by the Cochrane Review Groups), including a summary of the review and a critical appraisal of its overall quality

Question 16

The following is one of the databases that make up the Cochrane Library; what is this and what does it do?

3) CENTRAL

Answer 16

The Cochrane Central Register of Controlled Trials (CENTRAL) - contains details of articles of Controlled trials

Question 17

The following is one of the databases that make up the Cochrane Library; what is this and what does it do?

4) CMR

Answer 17

The Cochrane Methodology Register (CMR) is a bibliography of publications that report on methods used in the conduct of controlled trials

Question 18

The following is one of the databases that make up the Cochrane Library; what is this and what does it do?

5) HTA

Answer 18

The Health Technology Assessment (HTA) Database brings together details of completed and ongoing health technology assessments (studies of the medical, social, ethical, and economic implications of healthcare interventions) from around the world

Question 19

The following is one of the databases that make up the Cochrane Library; what is this and what does it do?

6) NHS EED

Answer 19

NHS Economic Evaluation Database (NHS EED) - identifies economic evaluations from around the world and appraises their quality

Question 20

What is PsychINFO?

Answer 20

PsycINFO is a database of abstracts of literature in the field of psychology. It is produced by the American Psychological Association.

Question 21

What is CINAHL?

Answer 21

CINAHL is the Cumulative Index to Nursing and Allied Health Literature. It contains references to journal articles from hundreds of nursing journals from the UK, USA and other countries

Question 22

What is OpenGrey?
What was it formerly known as?

Answer 22

Formally called SIGLE (System for Information on Grey Literature in Europe), OpenGrey is a database dedicated to grey literature. Grey literature are materials and research produced by organizations outside of the traditional commercial or academic publishing and distribution channels. Organizations that produce grey literature include government departments and agencies, civil society or non-governmental organisations, academic centres and departments, and private companies and consultants

Question 23

What is Ovid?

Answer 23

Although not in itself a database it is important to have an understanding of Ovid.

Ovid (named after the Roman poet) is an interface used to search multiple databases. It was originally used to access Medline results but diversified once PubMed came out (which is free).

Question 24

What is Boolean Logic (in the context of PubMed)? 3 terms.

What is the default operator on PubMed?

Answer 24

Boolean logic refers to the logical relationships among search terms. The Boolean operators AND, OR, NOT can be used to combine search terms in PubMed. Boolean operators must be entered in uppercase letters.

AND is the default operator used in PubMed. If you do not include Boolean operators in your search, PubMed will automatically use AND between terms.

Question 25

What are Phrase Searching and Truncation, in the context of PubMed?

Answer 25

Phrase Searching:
PubMed automatically searches for phrases during Automatic Term Mapping. A phrase search can be forced however using double quotes.
Example: frontal leucotomy

Truncation:
Truncation, or finding all terms that begin with a given string of text, is generally not a recommended search technique for PubMed.
The PubMed truncation symbol is the asterisk ().
PubMed supports only end-truncation.
Example: neuro (will return a number of terms such as neurology, neuroscience, neuron)