3. Observational
Vs
Experimental
Observational study
• The investigator stands apart from the events
• He / She only observes and records the events
Experimental or intervention study
• The investigator introduces an intervention and
then observes the events
A practical guide for health researchers. Available at: https://apps.who.int/iris/handle/10665/119703
4. Observational
Studies
• A descriptive study is an observational study
that simply describes the distribution of a
characteristic
• An analytical study is an observational study
that describes associations and analyses them
for possible cause and effect.
A practical guide for health researchers. Available at: https://apps.who.int/iris/handle/10665/119703
5. Cross-
Sectional
Vs
Longitudinal
• An observational study may be cross-sectional
or longitudinal
• In a cross-sectional study, measurements are
made on a single occasion
• In a longitudinal study, measurements are
made repeatedly over a period of time
A practical guide for health researchers. Available at: https://apps.who.int/iris/handle/10665/119703
6. Retrospective
Vs
Prospective
• A longitudinal observational study may be
retrospective or prospective.
• In a retrospective study, the investigators study
present and past events.
• In a longitudinal prospective study, the
investigators follow subjects for future events.
A practical guide for health researchers. Available at: https://apps.who.int/iris/handle/10665/119703
7. Case–Control
Studies
• A group of subjects with a specified outcome
(cases) and a group of subjects without that
outcome (controls) are identified
• Investigators then compare the extent to which
each subject was previously exposed to the
variable of interest, such as a risk factor, a
treatment or an intervention.
A practical guide for health researchers. Available at: https://apps.who.int/iris/handle/10665/119703
8. Cohort Study
• In clinical and epidemiological research, a
longitudinal observational study is usually called
a cohort study
• A landmark cohort study was initiated by Austin
Bradford Hill and Richard Doll
• 40,000 British doctors were divided into four
cohorts: non-smokers, and light, moderate and
heavy smokers.
• The 20-year and 40-year results of this
momentous study showed that smoking caused
ill-health
A practical guide for health researchers. Available at: https://apps.who.int/iris/handle/10665/119703
9. Experimental
or
Intervention
studies
• The investigators test the effect of an
intervention on the events taking place
• Giving a treatment to a patient or group of
patients and finding that the treatment works
gives only preliminary and non-definitive
information.
• For a more definitive answer, we need a
“control” group of patients who do not get the
treatment under study.
A practical guide for health researchers. Available at: https://apps.who.int/iris/handle/10665/119703
10. • In testing the outcome in a group of patients
who receive the treatment and another group
who do not, we are still not sure whether any
difference observed is because of the treatment
or because the characteristics of the patients in
the two groups were different.
• The best way to be sure is to randomize the
allocation of patients to either treatment or to
no treatment.
Randomization
A practical guide for health researchers. Available at: https://apps.who.int/iris/handle/10665/119703
11. • Randomized controlled trials are intervention
studies characterized by the prospective
assignment of subjects, through a random
method, into an experimental group and a
control group.
• The control group receives a placebo, no
treatment, or the standard of care.
• Both groups are followed for the outcome(s) of
interest.
Randomized
Controlled
Trials
A practical guide for health researchers. Available at: https://apps.who.int/iris/handle/10665/119703
12. Cross-over
and
Before-and-
after study
• In a crossover study, half of the participants are
randomly assigned to start with the placebo and
then switch to active treatment, while the other
half does the opposite.
• A before-and-after study is a method of control
in which results from experimental subjects are
compared with outcomes from patients treated
before the new intervention was available.
These are called historic controls.
A practical guide for health researchers. Available at: https://apps.who.int/iris/handle/10665/119703
13. Blinding
• A randomized controlled trial may be blinded if
participants in the trial are likely to change their
behaviour in a systematic way that may
influence the outcome of the study when they
are aware of which intervention they receive.
• Blinding can take place at a number of levels
(Participants, Physician, Assessing individuals,
Researchers.)
• A trial in which there is no attempt at blinding
may be called open or open label.
A practical guide for health researchers. Available at: https://apps.who.int/iris/handle/10665/119703
14. CONSORT Statement:
Background
• Randomized controlled trials, when
appropriately designed, conducted, and
reported, represent the gold standard in
evaluating healthcare interventions.
• Complete, clear, and transparent information on
methodology and findings is required.
• Unfortunately, authors of many reports neglect
to provide desired descriptions and hence, the
assessment of the trial becomes difficult
http://www.consort-statement.org/
15. • Lack of adequate reporting led to the
development of the original CONSORT
(Consolidated Standards of Reporting Trials)
statement in 1996 and its revision in 2001.
• While those statements improved the reporting
quality for some randomized controlled trials,
many trial reports still remained inadequate.
• CONSORT 2010 is the latest update
http://www.consort-statement.org/
16. 4 Components
of CONSORT
• Statement
• Explanation and elaboration
• Checklist
• Flow Diagram
http://www.consort-statement.org/
22. Reporting of Multi-Arm Parallel-Group Randomized
Trials: Extension of the CONSORT 2010 Statement
Reporting of stepped wedge cluster randomised
trials: extension of the CONSORT 2010 statement
with explanation and elaboration
Reporting randomised trials of social and
psychological interventions: the CONSORT-SPI 2018
Extension
CONSORT 2010 statement: extension checklist for
reporting within person randomised trials
CONSORT Extension for Chinese Herbal Medicine
Formulas 2017: Recommendations, Explanation, and
Elaboration
CONSORT 2010 statement: extension to randomised
pilot and feasibility trials
The CONSORT Statement: Application within
and adaptations for orthodontic trials
CONSORT extension for reporting N-of-1 trials
(CENT) 2015 Statement
Better reporting of harms in randomized
trials: an extension of the CONSORT Statement
Reporting of patient-reported outcomes in
randomized trials: the CONSORT PRO extension
Improving the reporting of pragmatic trials: an
extension of the CONSORT statement
CONSORT for reporting randomised trials in
journal and conference abstracts
CONSORT Statement for Randomized Trials of
Nonpharmacologic Treatments: A 2017 Update
and a CONSORT Extension for
Nonpharmacologic Trial Abstracts
http://www.equator-network.org/
23. Checklist for the preparation and review of pain
clinical trial publications: a pain-specific supplement
to CONSORT
Improving the reporting of clinical trials of infertility
treatments (IMPRINT): modifying the CONSORT
statement
Reporting Guidelines for Health Care Simulation
Research: Extensions to the CONSORT and STROBE
Statements
CONSORT-EHEALTH: improving and standardizing
evaluation reports of Web-based and mobile health
interventions
Reporting randomized, controlled trials of herbal
interventions: an elaborated CONSORT Statement
Consort 2010 statement: extension to cluster randomised
trials
Reporting of noninferiority and equivalence randomized
trials: extension of the CONSORT 2010 statement
Revised STandards for Reporting Interventions in Clinical
Trials of Acupuncture (STRICTA): extending the CONSORT
statement
CONSORT-Equity 2017 extension and elaboration for
better reporting of health equity in randomised trials
http://www.equator-network.org/
25. CONSORT for Ayurveda
• Under process
• TDU has taken initiative in framing this
Tillu G. Workshop on a CONSORT statement for Ayuveda. J Ayurveda Integr Med. 2010;1(2):158–159.
26.
27. Guidelines for reporting
observational studies
• The Strengthening the Reporting of Observational
Studies in Epidemiology (STROBE) Statement
• The STROBE Statement is a checklist of items that should
be addressed in articles reporting on the 3 main study
designs of analytical epidemiology:
• Cohort studies
• Case-control studies
• Cross-sectional studies
https://www.strobe-statement.org/index.php?id=strobe-home
30. STROBE-Extensions
CONSISE statement on the reporting of Sero-
epidemiologic Studies for influenza (ROSES-I statement):
an extension of the STROBE statement
Strengthening the Reporting of Observational Studies in
Epidemiology for Newborn Infection (STROBE-NI): an
extension of the STROBE statement for neonatal infection
research
Strengthening the Reporting of Observational Studies in
Epidemiology—Nutritional Epidemiology (STROBE-nut):
An Extension of the STROBE Statement
STROBE-AMS: recommendations to optimise reporting of
epidemiological studies on antimicrobial resistance and
informing improvement in antimicrobial stewardship
The REporting of studies Conducted using Observational
Routinely-collected health Data (RECORD) Statement
Strengthening the Reporting of Observational Studies in
Epidemiology for Respondent-Driven Sampling Studies:
‘STROBE-RDS’ Statement.
Strengthening the reporting of molecular epidemiology
for infectious diseases (STROME-ID): an extension of the
STROBE statement
Draft STROBE checklist for conference abstracts
STrengthening the Reporting of OBservational studies in
Epidemiology – Molecular Epidemiology (STROBE-ME):
An extension of the STROBE statement
http://www.equator-network.org/
31. STrengthening the REporting of Genetic
Association Studies (STREGA): An Extension of
the STROBE Statement.
Reporting Guidelines for Health Care Simulation
Research: Extensions to the CONSORT and
STROBE Statements
Launch of a checklist for reporting longitudinal
observational drug studies in rheumatology: a
EULAR extension of STROBE guidelines based on
experience from biologics registries
http://www.equator-network.org/
35. CARE Extensions
• Adaptation of the CARE Guidelines for Therapeutic
Massage and Bodywork Publications: Efforts To
Improve the Impact of Case Reports
• The SCARE 2018 Statement: Updating Consensus
Surgical CAse REport (SCARE) Guidelines
• Homeopathic clinical case reports: Development
of a supplement (HOM-CASE) to the CARE clinical
case reporting guideline
http://www.equator-network.org/