This document provides an overview of evidence-based medicine and how to critically appraise clinical papers. It discusses how evidence-based medicine involves using both clinical expertise and the best available external evidence in decision making. The origins of evidence-based medicine in the 1970s and 1990s are also reviewed. The document then focuses on how to critically read clinical papers, including the key things to assess for diagnostic tests, clinical course/prognosis, causation, and therapy papers. It provides guidance on an appraisal format and emphasizes the need to both evaluate the study and summarize what it was about. Evidence-based medicine is positioned as an important guide but not a replacement for clinical expertise and judgment.

1. Critical Appraisal
Jamalludin Ab Rahman MD MPH
Department of Community Medicine

2. Evidence Based Medicine
“Evidence based medicine is the conscientious, explicit, and judicious
use of current best evidence in making decisions about the care of
individual patients.”
“Good doctors use both individual clinical expertise and the best
available external evidence, and neither alone is enough.”
“External clinical evidence can inform, but can never replace,
individual clinical expertise…”
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Sackett, D. L., Rosenberg, W. M. C., Gray, J. A. M., Haynes, R.
B., & Richardson, W. S. (1996). Evidence based medicine:
what it is and what it isn't (Vol. 312).

3. The origin of EBM
 1975, Dr David L Sackett discovered that the factor that
determine the prescription for hypertension is the
graduating years of the doctors.
 1990, Dr Gordon Guyatt coined the term Evidence
Based Medicine for a new Internal Medicine residency
programme known as “Scientific Medicine”
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Kowalski, E., & Chung, K. C. (2013). The outcomes movement and
evidence-based medicine in plastic surgery. Clin Plast Surg, 40(2), 241-
247. doi: 10.1016/j.cps.2012.10.001

4. What is EBM
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Personal
(maybe obsolete) own
experience
External
(and current) evidences

5. Why we read clinical papers?
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Sackett, D. (1981). How to read clinical journals. 1. Why to read them and how to start reading
them critically. Canadian Medical Association Journal, 124(5), 555-558.

6. How to critically read the journal?
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First critical step is to know what information you
are looking for in the first place?
1. Diagnostic test
e.g. Using central blood pressure (pulse wave analysis) to
measure risk of CAD, compared to peripheral blood
pressure.
2. Clinical course & prognosis
e.g. 5-years survival of cancer patients following an
operation procedure.
3. Aetiology & causation
e.g. Talcum causing cancer.
4. Therapeutic
e.g. New drug is better than the old one.
Sackett, D. (1981). How to read clinical journals. 1. Why to read them and how to start reading
them critically. Canadian Medical Association Journal, 124(5), 555-558.

7. Diagnostic
 Evaluate new diagnostic test
 Compare to GOLD standard
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8. www.iium.edu.my 15 September 2014
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How to read clinical journals: II. To learn about a diagnostic test. (1981).
Canadian Medical Association Journal, 124(6), 703-710.

9. Prognosis
 Clinical course of a disease – e.g. Recurrence rate, 3-
year survival, reinfection etc.
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10. www.iium.edu.my 15 September 2014
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How to read clinical journals: III. To learn the clinical course and prognosis
of disease. (1981). Can Med Assoc J, 124(7), 869-872.

11. Causation
 About one causing the other e.g. smoking causing lung
cancer
 Hierarchy of evidence
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12. Hierarchy of evidence
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13. www.iium.edu.my 15 September 2014
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How to read clinical journals: IV. To determine etiology or causation. (1981). Can Med
Assoc J, 124(8), 985-990.

14. Therapy
 How useful or harmful of a therapy e.g. prescribe high
dose vitamin C for cancer patient; low dose aspirin for all
hypertensive patients
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15. www.iium.edu.my 15 September 2014
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How to read clinical journals: V: To distinguish useful from useless or even
harmful therapy. (1981). Can Med Assoc J, 124(9), 1156-1162.

16. Appraisal Format
1. Credibility of the journal & authors
2. Title – Clear & informative (explained well about the paper)
3. Summarise the study – With your own words, summarise the study
4. Keywords - Relevant
5. Abstract – How it was done? Structured or non-structured. How the study was summarised? Do you feel
the information provided adequate?
6. Introduction – Study justified (rationale); objectives clearly stated
7. Methodology – Design, Sampling method, Sample size, Data definition, Data collection, Statistical
analysis, Ethical issues
8. Results – Answers the objectives, Consistent, Clear illustrations or tables
9. Discussion – Answers the objectives, Discuss the strength & weakness of the study
10. Conclusion of the appraisal
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17. Don’t forget to tell about the study
 Don’t just write all about your comments
 Must include what is the study is all about
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18. EBM is a guide
 …and will always be just a guide
 Horses for courses
 Cross sectional studies still have important place in
research, esp. evidence based policy
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19. Main references
 Fowkes, F. G., & Fulton, P. M. (1991). Critical appraisal of published research: introductory guidelines (Vol.
302).
 How to read clinical journals: II. To learn about a diagnostic test. (1981). Canadian Medical Association
Journal, 124(6), 703-710.
 How to read clinical journals: III. To learn the clinical course and prognosis of disease. (1981). Can Med
Assoc J, 124(7), 869-872.
 How to read clinical journals: IV. To determine etiology or causation. (1981). Can Med Assoc J, 124(8),
985-990.
 How to read clinical journals: V: To distinguish useful from useless or even harmful therapy. (1981). Can
Med Assoc J, 124(9), 1156-1162.
 Greenhalgh, T. (1997). How to read a paper. Getting your bearings (deciding what the paper is about).
Bmj, 315(7102), 243-246.
 Sackett, D. (1981). How to read clinical journals. 1. Why to read them and how to start reading them
critically. Canadian Medical Association Journal, 124(5), 555-558.
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