1. Critical Reading of Medical Articles
Introduction to Primary Care
a course of the Center of Post Graduate Studies in FM
PO Box – Riyadh 11417
Tel: – Fax:

2. Aim: knowledge on the principles of critical reading (appraisal) of medical articles.
Objectives: at the end of this presentation, the participants should be able;
to assess the quality of the article to determine if the conclusions are valid
to explain how to start reading
to explain the results of an article and their relevance to your practice.

3. What is critical reading ?
The assessment of evidence by systematically reviewing its relevance, validity and results to specific situations.
- Chambers, R. (1998).
It is an essential skill for evidence-based medicine.

4. Why read medical articles critically?
Convert our information needs into answerable questions.
Track down, with maximum efficiency, the best evidence with which to answer these questions.
Appraise the evidence critically, assess its validity and usefulness (clinical applicability).

5. 4.To implement the results of this appraisal into our clinical practice.
5.To evaluate our performance.
Published research is not always reliable or
relevant.

6. Difficulties with Critical Appraisal
Can be time consuming initially
Doesn’t provide an “easy” answer
It could show a lack of good evidence in a particular topic

7. Key Steps to Effective Critical Appraisal
1. Are the results valid?
2. What are the results?
3. How will these results be relevant to
the patient?

8. Basic elements of clinical decision making

10. Steps to EBM 1. Formulate a clear, focused clinical question
2. PICO model
3. Search the literature for the best external
evidence
4. Critically appraise the evidence for its validity
and usefulness
5. Implement the useful evidence in clinical
practice
6. Evaluate the results

11. Different types of question require different study designs
what caused this illness?
Atiology:
what does this test result mean?
Diagnosis:
what is likely to happen to this patient?
Prognosis:
is having been exposed to this substance likely to do harm, and, if so, what?
Harm:
is this treatment likely to help patient with this illness?
Effectiveness
what are the outcomes that are most important to patients with condition?
Qualitative:

12. Study designs for Question Types
Diagnosis
Prospective cohort study with good quality validation against “Gold Standard”
Therapy
Randomized controlled clinical trial (RCT)
Etiology/
Harm
RCT, cohort or case-control study (probably retrospective)
Prognosis
Prospective cohort study

13. PICO Structure
Patients P
Intervention I
Comparison C
Outcome O

14. Clinical Scenario
What therapeutic agents can be used for rate control of atrial fibrillation (AF) in a patient with congestive heart failure (CHF)?

15. Starting Point Break the question into the following components:
Population: Patients with atrial fibrillation AND congestive heart failure
Intervention: Rate control
Comparison: N/A
Outcome: Mortality, effectiveness of rate control

17. MeSH
Medline Subject Headings (MeSH terms) are assigned to each article.
Provide consistent way to retrieve articles
MeSH “a controlled vocabulary organised in a tree structure”
index = like chapter headings in a text book
Major Subject Headings (eg Leg)
Subject Headings (eg knee)
Subheadings (eg cruciate ligament)

18. How can we do Critical Appraisal?
Use common sense
Use simple checklists
Use different checklists depending on the different types of studies (i.e., RCTS, systematic reviews etc)
Checklists help you focus on the important parts of the article

19. Research Methodology Who were the participants of the study?
How were they recruited?
Was there bias in the recruiting methods?
How was the data collected?
What statistical tests were used?
Where the data collection methods accurate?

20. Critical appraisal questions
What is the paper about?
Why was the study done?
What type of study was done?
Was it primary research (experiment, RCT, cohort, case-control, cross-sectional, longitudinal, case report/series)?

21. Critical appraisal questions
Was it secondary research (overview, systematic review, meta-analysis, decision analysis, guidelines development, economic analysis)?
Was the design appropriate (for study on treatment, diagnosis, screening, prognosis, or causation)?
Was the study ethical?

22. What makes studies reliable?
First look for biases in the study.
Bias can be defined as ‘the systematic
deviation of the results of a study from the
truth because of the way it has been
conducted, analysed or reported’.

23. Key sources of bias in clinical trials
Biased allocation to comparison groups
Selection bias
Unequal provision of care apart from treatment under evaluation
Performance bias
Biased assessment of outcome
Detection bias
Biased occurrence and handling of deviations from protocol and loss to follow up
Attrition bias

24. A study which is sufficiently free from bias is said to have internal validity
Different methods of collecting evidence are graded as to their relative levels of validity.
To minimise bias, double-blind randomised controlled trials are the best for evidence.

25. A system for reading an original article
First, “scan” the article:
-A brief review of the length, headings, key and concluding sentences of each section is worthwhile.
-How much time it will take to read the article carefully
-Provoke questions or the need for clarification which will direct your focus during a second detailed reading.

26. In general, original articles will comprise:
A title
An abstract or summary
A methods (and materials) section
Results
Discussion
References

27. A title A title will normally contain three elements :
-setting (types of patients and circumstances under which the study is performed)
intervention (in prospective randomised controlled trials) or study factor
outcome measure
E.g. Effect of carbon dioxide neumoperitoneum [ intervention] on development of atlectasis
[ outcome] during anaesthesia [setting].

28. BACKGROUND INFORMATION (Intro) Author, Journal, Type of Study.
AIM Research Question? Well defined? Worthwhile? (Intro) Appropriate? Tested properly by method?
BACKGROUND INFORMATION (Intro) Author, Journal, Type of Study.
Strengths/weaknesses
SETTING Primary/secondary care? Type of practice?
(Method) Strengths/weaknesses
C) SAMPLE Large enough? Comparable with normal (Method) population? Randomly selected? Biased? Inclusion/exclusion criteria?

29. CONTROLS Used or not? How were they selected?
(Method) Matched for all relevant factors?
Any confounding factors?
DESIGN Appropriate? Retrospective or prospective? (Method) Quantitative/qualitative? Observational/ Experimental? Double blind? Placebo controlled?
DATA Were questionnaires piloted? Response rate? (Method/results) Outcome measures defined?Was measurement validated/reliable? Understandable clear data represented accurately? Are statistics appropriate?

30. ETHICAL Local Ethics Committee Approval?
Pt consent?
EVALUATION Summary of findings. Study strength and (Discussion) limitations. Comparison with existing literature. Answer research question?
EFFECTIVE Are conclusions made in discussion justified (Discussion) by results? Clinically significant? Clinically relevant? Clinically applicable?

31. Stats…..! Means to compare samples of populations
P values : The probability that any particular out come would have arisen by chance p < 0.05 = statistically significant
Confidence Intervals : Estimated range that is likely to include the true value
Numbers Needed to Treat :
Estimated number of patients that need to be treated with a new treatment for one additional patient to benefit

32. Predictive Value of tests
Confidence Intervals
Relative Risk Reduction
Intention to treat
Relative Risk
P Value
Absolute Risk Difference
Sensitivity
Absolute Risk Reduction
Absolute Benefit Increase
Specificity
Likelihood Ratio
Numbers Needed to Treat (NNT)
Odds Ratio

33. READER acronym to aid critical reading MacAuley. BJGP 1994; 44,83-85
Relevance - reader’s context
Education behaviour modification
Applicability - readers own practice
Discrimination validity, quality
Evaluation - scoring system
Reaction what to do with the paper..!