OVERVIEW

LN Yaddanapudi

Dept. of Anaesthesia and Intensive Care, PGIMER, Chandigarh

How to conduct a clinical trial Research question Study designs CONSORT step-by-step Sample size and power calculations Randomization and blinding Data processing Simple-minded guide to hypothesis

testing

Developing a research question

Research Process

Research question Background of the research Study design Study population Study variables Data Collection Quality control Statistical analysis Dissemination of data

Good research depends on a clear question understanding the context of the

question being able to use appropriate methods

to answer the question knowing when to stop

Starting points Discussion with a supervisor or colleagues,

email, discussion groups, mailing lists Databases - Cochrane, NEXUS, Project

Impact. "further research needed" sections of journal

articles, papers, theses and dissertations in the subject area of your interest

Topic definitions in encyclopaedias and "state-of-the-discipline" reviews in the journal literature

What are you looking for? topics where there is doubt and uncertainty disputed or contradicted statements topics where evidence is incomplete,

lacking, dated topics where evidence from a study on one

community or group could be compared with evidence from an associated group

topics which interest you

Requirements Mastering the literature Being alert to new ideas and techniques

ConferencesMeet researchersSkeptical attitudeNew technologies

ImaginationObservationTeachingCreativityTenacity

Choosing a mentor

Good research question Feasible

No. of Subjects Technical expertise Affordable in time and money Manageable in scope

Interesting Novel

Confirms, refutes or extends previous findings New findings

Ethical Relevant

Scientific knowledge Clinical and health policy Future research

Study designs

Descriptive studies

Case reports Case series Population studies

Descriptive studies: Uses

Hypothesis generating

Suggesting associations

Analytical Studies

ObservationalCross-sectionalCase-controlCohort

Experimental

Cross-sectional studies

CharacteristicsData collected at single point of timeDescribes associationsPrevalence

StrengthsQuickCheap

WeaknessesCan’t establish cause-effect

Case-Control Study

Start with people who have disease Match them with controls that do not Look back and assess exposures

Case-Control Study: Strengths Good for rare outcmes Can examine many exposures Useful to generate hypotheses Fast Cheap Provides Odds Ratio

Case-Control Study: Weaknesses

Cannot measureIncidencePrevalenceRelative Risk

Can only study one outcome High susceptibility to bias

Cohort Study

Begin with disease-free patients

Classify patients as exposed/unexposed

Record outcomes in both groups

Compare outcomes using relative risk

Cohort Study: Strengths

Provides incidence data

Establishes time sequence for causality

Eliminates recall bias

Allows for accurate measurement of exposure

variables

Can measure multiple outcomes

Can adjust for confounding variables

Can calculate relative risk

Cohort Study: Weaknesses Expensive

Time consuming

Cannot study rare outcomes

Confounding variables

Exposure may change over time

Disease may have a long pre-clinical phase

Attrition of study population

Clinical Trials

Randomized

Double-blind

Placebo-controlled

Randomized Controlled Trial

Study Population

Ran

dom

izat

ion

Treatment Group

Outcome

No Outcome

Control Group

Outcome

No Outcome

Clinical Trials

Strengths:Best measure of causal relationshipBest design for controlling biasCan measure multiple outcomes

Weaknesses:High costEthical issues may be a problemCompliance

Clinical decisions

Evidence

Clinical Audit

Strategies to

implement guidelines

Practice guidelines

Technology assessment

Economic studies

Systematic reviews

Primary studies

Pat

ient

’s c

ircum

stan

ces

and

wis

hes