Evidence-Based Medicine

Dr.Ankit Desai(Ortho)Dr.B.L.Chandrakar

What Is Evidence-Based Orthopaedics?

• The term evidence-based medicine (EBM) first appeared in autumn 1990 in a document for applicants to the internal medicine residency program at McMaster University that described EBM as an attitude of enlightened skepticism toward the application of diagnostic, therapeutic, and prognostic technologies.

To Practice of EBM requires

• ¤A clear delineation of relevant clinical questions

• ¤ A thorough search of the literature relating to the questions

• ¤ A critical appraisal of available evidence and its applicability to the clinical situation

• ¤ A balanced application of the conclusions to the clinical problem

• In simple Words • “Integration of best research evidence with

clinical expertise and patient value”

Objectives

1. Describe the use of evidence in making medical decisions

2. Demonstrate searching for an evidence-based answer to a medical question

What is “EBM” NOT?

• What we have always done

• “Cookbook medicine”• Only a cost-cutting trick• Only randomized trials

Evidence based medicine IS… Tracking down the best

external evidence with which to answer our clinical questions…

Hierarchy Of Evidence

• Among various study designs, there exists a hierarchy of evidence with

• randomized controlled trials at the top, • controlled observational studies in the

middle, and • uncontrolled studies and opinion at the

bottom.

Sackett et al have proposed a grading system

• (i) grade A consistent level 1 studies

• (ii) grade B consistent level 2 or level 3 studies

• (iii) grade C level 4 studies

• (iv) grade D level 5 evidence.

Meta-Analysis

Single RCT

Cohart Studies

Case- Controlled Trial

Case Series

Expert opinion

Study Designs

Analytical studies Descriptive Studies

Cross sectional studies, case reports, and case series

Observational studies, Experimental

studies.

case-control and cohort studies

Randomized clinical trials

Meta-Analysis (Level 1 Evidence; Grade A Recommendation)

• meta-analysis, it is frequently used in the surgical literature.

• A meta-analysis is a systematic review that combines the results of multiple studies (of small sample size) to answer a focused clinical question.

• retrospective in nature. →

• increased impact over traditional reviews (e.g., narrative or nonsystematic reviews).

• its value is diminished when poor quality studies… are included in the pooling.

Randomized Trial (Level 1 Evidence; Grade A Recommendation)★★★

• Randomized trial is the single most important design to limit bias In clinical research.

• Randomization gives a patient entering a clinical trial an equal probability (or chance) of being allocated to alternative treatments

• Patients can be randomized to alternative treatments by random number tables or computerized randomization systems.

• Randomization is the only method for controlling for known and unknown prognostic factors between two comparison groups

Concept Of Concealment:

• surgeons are unable to predict the treatment to which their next patient will be allocated.

• remote 24-hour telephone randomization service.

• Double blinding is impossible in almost all surgical procedures

Results Of Trial: Can be analyzed in two ways.

• intention to treat analysis:(intervention to which the patients were randomized )

• Per protocol analysis:(according to the treatment they actually received )

Observational Study (Cohort) (Level 2 Evidence; Grade B Recommendation)

• It is nonrandomized, or observational, study designs.

• study identifies a group of patients at a similar point in time and follows them forward in time.

• → Outcomes are determined prior to the start of the study and evaluated at regular time intervals until the conclusion of the study.

• → A comparison group (controls) may also be identified concurrently and followed for the same time period.

• these types of studies can assist surgeons in discussing the expected risk and outcomes of surgery with their patients during the informed consent process.

Case-Control Study (Level 3 Evidence; Grade B Recommendation)

• If the outcome of interest is rare (e.g., mortality or infection), conducting a prospective cohort study may be cost prohibitive.

• A case-control study is a useful strategy in such circumstances.

• Cases with the outcome of interest are identified retrospectively from a group of patients (e.g., databases) and matched (e.g., by age, gender, severity of injury) with control patients who do not have the outcome of interest.

Population

Exposed

Not exposed

exposed

notexposed

Contorls (without disease )

Case (with disease )

time

Direction of inquiery

Case-Control Study

Population

exposed

disease no disease no disease

Disease

not exposed

Without disease

Design of a Cohort Study

Time And Direction

In short… EBM is the conscientious,

explicit, and judicious use of current best evidence in

making decisions about the care of individual patients.

EvidenceSystematic observation =

high-quality evidence

Patient-oriented evidencepreferable to

Stage of diseasepreferable to

Surrogate markers