Medical literature: a quick guide

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Medical literature a quick guide
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What are the types of publications?

• Primary research
• Secondary research
• Tertiary research
• The closer to primary, the more _____________ the
  research.

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What is primary literature?

• Backbone of science
• Synopsis of lab and analytical work
• Always peer reviewed (well discuss this shortly)

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What is primary literature?
Observation My floors are really filthy

• Based on hypothetico-deductive method
• Form hypothesis and null hypothesis
• Derive if-then statements and test
• Goal reject null hypothesis
• Another goal support hypothesis!

Hypotheses My dogs make the floor dirty My
husband makes the floor dirty
If-Then Statements If my dogs make it dirty,
then I will see dog hair on the floor If my
husband makes it dirty, then I will see socks and
other junk on the floor
Test statements
Conclusion
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What are type I and II errors?

• Type I error accidentally reject null when you
  should have accepted it.
• Type II error accidentally reject alternate
  hypothesis when you should have accepted it.

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What is peer review?
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What is peer review?

• Researchers in same topic area review and edit
  submitted works
• Works published only after editing and approval
• Quality control system
• Peer-reviewed papers are the most credible
  sources of information
• Almost all primary literature is peer-reviewed
• If it isnt, consider the information twice!

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How do I identify peer-reviewed journals?

• Look for contributing author instructions
• Look at first page of article for list of dates
• Submitted
• Revised
• Accepted

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What is secondary literature?

• AKA review papers
• Summary/synthesis of primary lit. in one topic
  area
• Addresses current research on a question
• Authors often write them to present new
  hypothesis before doing research
• Allows them to scoop other researchers
• Many studies weighed against each other
• Exhaustive evaluation
• Usually peer-reviewed

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What is tertiary literature?

• Least likely of three types to be accurate
• Why?
• Articles usually aimed at people who are not
  experts on the subject
• Frequently made for the lay person
• Very common that writer has no background in
  topic area
• e.g. reporters

From http//www.theonion.com/content/node/42603
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How do I know Im looking at primary literature?

• Format
• Abstract
• Introduction
• Methods
• Double-blind is the gold standard
• Random sample, at least 20 subjects, much better
  if 100
• Results
• Conclusion (discussion)
• Usually peer-reviewed
• Authors credentials always identified

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Where do I find primary literature?

• Journals covering narrow topic area
• J. of Orthopaedic and Sports Physical Therapy
• Postgraduate Medicine
• J. of Infectious Diseases
• Libraryalmost all primary lit. is by
  subscription only

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How do I know Im looking at secondary literature?

• A bit more general than primary lit.
• Usually longer, with very long citations section
  (sometimes into the hundreds!)
• Often with table of contents
• Title often includes phrases like
• A review of
• New ideas/insights/thoughts on
• An update on
• A history of
• Advances in
• Perspectives on
• Methods section missing

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Where do I find secondary literature?

• Librarysame reason as for primary lit.
• Some review article appear in journals which
  mostly print primary lit.
• Others appear in review-exclusive journals
• Annual Review of Pharmacology
• Annual Review of Immunology
• Annual Review of Medicine
• Trends in molecular medicine
• Advances in oto-rhino-laryngology

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How do I know Im looking at tertiary literature?

• Very non-technical language
• Aimed at general audience
• No abstract, no citations
• If citations present, only a few and most often
  very general
• Shorter article
• Lacks technical information/discussion

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Where do I find tertiary literature?

• Just about anywhere
• Newspapers
• Encyclopedias
• Textbooks
• Magazines
• Website summaries (e.g. government)

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What about the Internet?

• All three type of literature here
• Use extreme caution!
• Anyone with a computer and Internet access can
  publish
• Many web resources not editor-verified
• Or peer-reviewed!
• Very often difficult to determine authorship
• If available, still may not list authors
  credentials
• Money motivates persuasive articles
• The virtual soapbox
• Our product is a miracle, unbelievable results
• Dates often not included
• You could be reading out-of-date information

From http//www.infratrans.gov.ab.ca/
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What are clinical trials?

• Research studies involving people
• Prospective studiesyes
• Framingham Heart Study
• Retrospective studiesno
• Types of clinical trials
• Treatment trial
• Prevention trial
• Early-detection/screening trial
• Diagnostic trials

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What are the different stages of clinical trials?

• Phase I
• 15-30 people
• Goals
• Find safe dosage
• Decide how to give agent
• Observe affects of agent on humans (side effects,
  etc.)

From http//depts.washington.edu/mednews/vol7/no0
8/mapotheworld.jpg
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What are the different stages of clinical trials?

• Phase 2
• About two-thirds of drugs make it this far
• lt 100 people
• Drug tested for efficacy
• Control and placebo groups
• Usually double-blind experiment
• Also monitor safety

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What are the different stages of clinical trials?

• Stage 3
• 100-thousands
• Demonstrates efficacy on large number of people
• Still monitoring efficacy and side effects
• Allows comparison of new approach/drug with old
  drugs/approaches
• Helps fine-tune drug dosages
• Can apply for FDA approval at end of trial

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What are the different stages of clinical trials?

• Phase 4
• Several hundred to several thousand
• Evaluate long-term safety and efficacy
• Drug/approach now in general use

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Its quiz time!

• Identify (not out loud!) whether each is primary,
  secondary or tertiary.

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