Evidence-based medicine involves integrating clinical expertise with the best available external clinical evidence from systematic research. It includes formulating clinical questions, searching literature, evaluating evidence, and applying evidence to individual patient care. The highest levels of evidence come from randomized controlled trials, while lower levels include observational studies and expert opinion. Clinical trials progress through phases to evaluate safety, efficacy, and effectiveness of interventions. Statistical analysis of trial results provides measures of significance, risk, and accuracy to guide clinical decision-making.

1. Evidence Based Medicine
Doing what is right

2. Definition
 Conscientious, explicit, judicious use of
current best evidence in making
decisions about care of an individual
patient
 Involves integrating individual clinical
experience with best external evidence
from systematic research

3. Types of EBM
 Evidence based guidelines- production
of guidelines, policy and regulations to be
used at the organizational or institutional level
 Evidence based individual decision
making- use of available evidence to provide
best treatment to an individual patient, by an
individual physician

4. Answering clinical question
 Formulate a question
 Search the literature
 Evaluate the literature
 Apply available evidence in management

5. Stratifying evidence
 Prospective, randomised, double-blind placebo
controlled trial
 Prospective, randomised double-blind comparative
trial
 Systematic review- Meta-analysis
 Prospective controlled trial, without randomisation
 Sub-group analysis or Retrospective study
 Uncontrolled trials- Cohort/Case-control studies
 Case series or case reports
 Expert opinion

6. Levels of evidence
 I- from at least one RCT
 II- from controlled trials without
randomization, multicentric case-control
or cohort studies or uncontrolled trials
 III- opinions of respected authorities,
based on clinical experience or reports
of expert committees

7. Categories of
recommendation
 A- good scientific evidence that
benefits >>> potential risks
 B- fair scientific evidence that
benefits >> potential risks
 C- fair scientific evidence that
benefits > potential risks
 D- fair scientific evidence that
risks > benefits
 I- insufficient scientific evidence

8. Clinical trial
 Study done to allow safety and efficacy
data to be collected for health
interventions
 Needs a protocol
 Investigators recruit patients, administer
treatment, collect data over specified
time period
 Data is analysed using statistical tests

9. Types of Clinical trials
 Prevention trial
 Screening trial
 Diagnostic trial
 Treatment trial
 Quality of life trial
 Compassionate use trial

10. Terms
 Randomised- subjects are randomly
assigned
 Double-blind- subjects and researchers do
not know the treatment being given, to
prevent any bias
 Placebo controlled- use of placebo helps
isolate the effect of study treatment

11. Phases of Clinical trials
 Pre-clinical studies- in-vitro or animal
studies to obtain preliminary efficacy,
toxicity and pharmacokinetic data
 Phase 0- subtherapeutic doses to few
patients to get pharmacokinetic and
pharmacodynamic data

12. Phases- contd.
 Phase I- assesses safety, tolerability and
dose range in healthy volunteers
 Phase II- assesses dose and efficacy in a
larger group of volunteers and patients
 Phase III- randomised controlled
multicenter trials on large patient group for
effectiveness of the treatment
 Phase IV- post-marketing safety surveillance

13. Statistical terms
 p-value- <0.05 considered significant
 Relative risk- risk of an event relative to
exposure
 Hazard ratio- ratio between the predicted
hazard for members of two groups
 Odds ratio- ratio of the odds of an event
occurring in one group to the odds of it
occurring in another group

14. Statistical terms- contd.
 SeNsitivity- probability of a positive test
result in someone with target disease
i.e. true Positive
 SPecificity- probability of a negative test
result in someone without the disease
i.e. true Negative

15. Statistical terms- contd.
 Number needed to treat (NNT)-
number of patients needed to treat to
prevent one clinical event
NNT= 1/absolute risk reduction
 Number needed to harm (NNH)-
for harmful effects of the treatment

16. Quality of Clinical trials
 Clearly defined eligibility criteria and have
minimal missing data
 Results must be generalizable in clinical
practice
 Adequate follow-up for defined outcomes to
occur and to detect differences between arms
of study
 Sufficient number of patients to detect a
significant difference

17. Limitations
 Ethical issue of offering or not, of an unproven
treatment
 Cost of trial and consequent source of funding
 Generalizability, comparability and extrapolation of
results
 Publication bias
 Use for rationing resources by economists,
policymakers and managers
 Availability of credible evidence
 Applying statistics to individuals