This document discusses different types of epidemiological study designs used to test hypotheses, including observational studies and experimental studies. It provides details on randomized controlled trials (RCTs), describing the basic steps in conducting an RCT which include developing a protocol, selecting and randomizing study populations, implementing interventions, follow up, and outcome assessment. It also discusses other types of experimental epidemiology studies like prevention trials, risk factor trials, cessation experiments, and trials evaluating health services. Non-randomized study designs are also briefly covered.
This presentation will help to get an insight into Epidemiological methods and describes details of Descriptive epidemiology. It will be useful to medical researcher as an initial input.
Observingthedistributionofdiseaseorhealth related events in human population.
• Identify the characteristics with which the disease is associated.
• Basically 3 questions are asked who, when and where.
• Who means the person affected, where means the place and when is the time distribution.
The STUDY of the DISTRIBUTION and DETERMINANTS of HEALTH-RELATED STATES in specified POPULATIONS, and the application of this study to CONTROL of health problems."
This presentation will help to get an insight into Epidemiological methods and describes details of Descriptive epidemiology. It will be useful to medical researcher as an initial input.
Observingthedistributionofdiseaseorhealth related events in human population.
• Identify the characteristics with which the disease is associated.
• Basically 3 questions are asked who, when and where.
• Who means the person affected, where means the place and when is the time distribution.
The STUDY of the DISTRIBUTION and DETERMINANTS of HEALTH-RELATED STATES in specified POPULATIONS, and the application of this study to CONTROL of health problems."
From History to Application Procedure OF CLINICAL TRIALS IN INDIA. PHASES 0,1,2,3,4 & 5.IMPORTANCE, advantages, guidelines global and India. Types, Design & blinding technique.
The randomised controlled trial (RCT) .pptxPRITIBISANE
Randomized controlled trials (RCT) are prospective studies that measure the effectiveness of a new intervention or treatment.
Randomization reduces bias and provides a rigorous tool to examine cause-effect relationships between an intervention and outcome
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Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
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Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
Recomendações da OMS sobre cuidados maternos e neonatais para uma experiência pós-natal positiva.
Em consonância com os ODS – Objetivos do Desenvolvimento Sustentável e a Estratégia Global para a Saúde das Mulheres, Crianças e Adolescentes, e aplicando uma abordagem baseada nos direitos humanos, os esforços de cuidados pós-natais devem expandir-se para além da cobertura e da simples sobrevivência, de modo a incluir cuidados de qualidade.
Estas diretrizes visam melhorar a qualidade dos cuidados pós-natais essenciais e de rotina prestados às mulheres e aos recém-nascidos, com o objetivo final de melhorar a saúde e o bem-estar materno e neonatal.
Uma “experiência pós-natal positiva” é um resultado importante para todas as mulheres que dão à luz e para os seus recém-nascidos, estabelecendo as bases para a melhoria da saúde e do bem-estar a curto e longo prazo. Uma experiência pós-natal positiva é definida como aquela em que as mulheres, pessoas que gestam, os recém-nascidos, os casais, os pais, os cuidadores e as famílias recebem informação consistente, garantia e apoio de profissionais de saúde motivados; e onde um sistema de saúde flexível e com recursos reconheça as necessidades das mulheres e dos bebês e respeite o seu contexto cultural.
Estas diretrizes consolidadas apresentam algumas recomendações novas e já bem fundamentadas sobre cuidados pós-natais de rotina para mulheres e neonatos que recebem cuidados no pós-parto em unidades de saúde ou na comunidade, independentemente dos recursos disponíveis.
É fornecido um conjunto abrangente de recomendações para cuidados durante o período puerperal, com ênfase nos cuidados essenciais que todas as mulheres e recém-nascidos devem receber, e com a devida atenção à qualidade dos cuidados; isto é, a entrega e a experiência do cuidado recebido. Estas diretrizes atualizam e ampliam as recomendações da OMS de 2014 sobre cuidados pós-natais da mãe e do recém-nascido e complementam as atuais diretrizes da OMS sobre a gestão de complicações pós-natais.
O estabelecimento da amamentação e o manejo das principais intercorrências é contemplada.
Recomendamos muito.
Vamos discutir essas recomendações no nosso curso de pós-graduação em Aleitamento no Instituto Ciclos.
Esta publicação só está disponível em inglês até o momento.
Prof. Marcus Renato de Carvalho
www.agostodourado.com
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
4.
EXPERIMENTAL
EPIDEMIOLOGY
In the 1920s,”experimental epidemiology” meant the
study of epidemics among colonies of experimental
animals such as rats and mice.in modern
usage,experimental epidemiology is often equated
with RCT.
AIMS
To provide a scientific proof.
To provide a measuring method.
5.
Animal studies
At the beginning of this century
,,WEBSTER(us)andTOPLEY,WILSONand
GREENWOOD(england) carried out animal
experiments.
ADVANTAGES
Experimental animals can be bred inlab,manpulated
easily according to investigator wishes.
Multyply rapidly
6.
Limitations:-
Not all the diseases reproduse in animals.
All the conclusions derived from animal
experiments may not be strictly appicable
to human beings.
EX:-WHO trial on typoid vaccine.-Almorth Wright
RCT trials.
Animal studies
7.
HUMAN EXPERIMENTS
Human experiments will always be needed to
investigate disease aetiology and to evaluate the
preventive and therapeutic measures.
These studies are even more essential in the
investigation of diseases that cannot be reproduced
in animals.
Ex: JAMES LIND
EDWARD JENNER
GOLDBERGER’S EXPERIMENT.
8. Although the experimental method is unquestionably
the most incisive approach to scientific problem, ethical
and Iogistic considerations often prevent its application
to the study of disease in humans.
Therefore, before launching human experiments, the
benefits of the experiment have to be weighed against
risks involved.
The volunteers should be made fully aware of all
possible consequences of the EXPERIMENT.
Thus when an illness is fatal (e.g., excessive
haemorrhage) and the benefit of treatment (e.g., blood
transfusion) is self-evident, it would be ethically
unacceptable to prove or disprove the therapeutic value
of blood.
9. However, such instances represent only a small part
of the total research effort.
On the other hand, in the present era of scientific
medicine, many unscientific or scientifically
unsound procedures are still being carried out.
EX;diethylstilbesteral-ca.vagina.
The WHO in 1980 has laid down a strict code of
practice in connection with human trials.
Experimental studies are two types.
A. RCT
B. NON-RANDAMOISED.
10.
It IS really an epidemiologic experiment.
Since its introduction. The RCT has questioned the
validity of such widely used treatments as oral
hypoglycemic agents, varicose vein stripping,
tonsillectomy, ……etc
For new programmes or new therapies, the RCT is
the No.1 method of evaluation.
RANDOMIZED
CONTROL TRIALS
11.
12. Basic steps in RCT conducting:
1.Drawing up a protocol.
2.Selecting reference and experimental
populations.
3.Randomization .
4.Manipulation or intervention
5.Follow –up
6.Assessment of outcome
13. It specifies:-
Aims &objectives of study
Questions to be answered
Criteria for selection of study and control groups
Size of sample
The procedures for allocation of subjects into study
and control groups.
Treatment to be applied.
Standardization of working procedures
Schedules and responsibilities of the parties
involved
1.The protocol
14.
AIM:-
preventing bias and to reduce the source
of errors in the study.
Preliminary test runs: some times it is useful
to have short test to run of the protocol to
see any flaws
Protocol
15.
REFERANCE POPULATION:-
Population to which the findings of the trail are
expected to be applicable.
Ex :-specific age group people
geographically limited
population of school children
SELECTING REFERENCE
&EXPERIMENTAL
POPULATION
16.
it is derived from reference population.
It is the population that actully participates in
experimental studies.
Participants must fullfil 3 criterias….
1.must give informed consent
2.should be representative of the population.
3.should be eligible for the trail.
EXPERIMENTAL POPULATION
17.
it is a statistical procedure by which
participents allocated in to study and control
groups.
it is a heart of RCT
It is an attempt to eliminate bias and allow for
comparability.
It will give greatest confidence that the groups are
comparable so that”like can be compared with like”.
RANDOMIZATION
18.
Randomization is done only after the participants
entered the study,that is after having been qualified
for the trial and has given informed consent to
participate in study.
Randomization best done by using a table of random
numbers.(simple random sample).random numbers
are a haphazard collection of certain
numbers,arranged in a cunning manner to eliminate
personal selection of unconscious bias in taking out
the sample.
Randomization
19.
After selection of study& control group,intervene the
study group by deliberate application(vaccine, drug)
as laid down in protocol.
This manipulation creates an independent varieble
(e.g. drug,vaccine)whose effect is then determined
by measurement of the final outcome,which
constitutes the dependent varieble(incidence of
disease,survival time.)
MANIPULATION
20.
This implies examination of the experimental &
control group subjects at defined intervals of time,in
a standard manner,with equal intensity,under the
same given circumstances,in the same time frame till
final assessment of outcome.
Attrition:-some cases losses to follow-up due to
death,migration,loss of intrest.
If the attrition is substantial,it may be difficult to
generalise the results to refferens population.
FOLLOW-UP
21.
POSITIVE RESULTS:-Benefits of experiment
measurers reduced incidence or severity of
disease…..
NEGATIVE RESULTS:-Severity and frequency of
side-effects and complications,if any,including death.
ASSESSMENT
22.
Bias may arise from errors of assessment of the
outcome due to human element.these may be from 3
sourses.
First - bias from the participants,who may
subjectively feel better or report improvement if they
knew they were receiving a new form of
treatment.known as subjective variation.
Second –investigater measuring the outcome of a
trial may be influnced if he knows beforehand the
particular therapy to which the pt has
subjected.(observer variation)
BIAS
23. BLINDING:-In order to reduce above
problems,blinding is adapted .it can be done in 3
ways.
A.Single blind trials:-participant is not aware of
group allocation.
B.Double blind trials:-neither doctor nor
participant is aware of group allocation.& Rx
received.
C.Triple blind trials:-participant,investigater and
person analysing data are blind.
Third there may be bias in evaluation.-the
investigator may give subconsciously give a
favorable report of the outcome of trial.
27.
For the most part,”clinical trials” have been
concerned with evaluting therapeutic agents,mainly
drugs.
Eg: trials of folate- to prevent NTD.
efficacy of tronsillectomy for recurrent
throat infections.
Many ethical, administrative, & technical problems
are involved in the conduct of clinical trials.
Types of RCT-1.clinical
trials
28.
It implies primary prevention.
Most common trials are done vaccines &
chemoprophilactic
Eg: Medical research concil of UK – woophing cough
since preventive trials involve larger number of subjects
and longer time span to obtain results,there may be
greater number of practical problems in their
organisation and execution.
2.Preventive trials
29.
A type of prevenive trials in which he investigator
internvenes to interrupt the usual sequence in the
development of disease for those individual who has
risk factor in developing the disease
Often this involves risk factor modification
Eg. CHD- 4 major risk factor- WHO study- clofibrate
therapy
OSLO study, MRFIT in US
3.Risk factor trial
30.
Another type of preventive trial is ihe cessation
experiment. In this type of study, an attempt is made to
evaluate the termination of a habit (or removal of
suspectedagent) which is considered to be causally
related to a disease.
If such action is followed by a significant reduction
in the disease, the hypothesis of cause is greatly
strengthened.
Ex :cigarette smoking-lung cancer.
Cessetion experiments
31.
One of the aim of experimental etiology is to confirm
or refute etiological hypothesis.
eg;: RLF
Since most disease are fatal,disabling, human
experiments to conform an aetiological hypothesis
are rarely possible.
5.Trial of etiological agents
32.
33.
RCT have been extended to assess the efectiveness &
efficiency of health services.
Eg: Domicilliary treatment- pulm. Tuberculosis.
Health services research studies.
6.Evaluaton of health
services
34.
Due to ethical, administrative, cost it is not always
possible to resort to RCT.
Approach is crude. As there is no randamisation,
degree of comparability will be low and chances of
spurious results will be high.
Non Randamized Trials
35.
1. Uncontrolled trials:
Trials with no comparision groups.
Useful to known whether specific therapy is
valuable for particular disease, to determine
the appropriate dose, to investigate adverse
reaction.
Eg:indirect epidemiological evidence that the
pap test is effective in reducing mortality from
cervical cancer.
Examples of non randamized trials
36.
2. Natural experiments:
Where experimental studies are not possible in human
beings, some natural circumstances mimics as
experiment
Eg: smokers and non smokers- lung cancer.
John snow discovery- cholera- water born disease.
Non-randomized trials
38.
3.BEFORE AND AFTER COMPARISON STUDIES:
These community trials fall into 2 distinct groups.
A.Before & after comparison studies without control.
B.Before & after comparison studies wth control
Non-Randomized trials
39.
These studies centre round comparing the incidence
ofdisease before and after introduction of a
preventive measure.
The events which took place prior to the use of the
new treatment or preventive procedure are used as a
standard for comparison.
In other words, the experiment serves as its own
control; this eliminates virtually all group
differences.
Before &after comparison
studies without control
40. Ex:James Lind –scury experiment
Prevention of polio by salk and sabin vaccine
In order to establish evidence in before and after
comparison studies, the following are needed; (a) data
regarding the incidence of disease, before and after
introduction of a preventive measure must be
available
(b) there should be introduction or manipulation of
only one factor or change relevant to the situation,
other factors remaining the same.
as for example, addition of fluorine to drinking water
to prevent dental caries
(c) diagnostic criteria of the disease should remain the
same
(d) adoption of preventive measures should be over a
wide area
(e) reduction in the incidence must be large following
the introduction of the preventive measure, because
there is no control.
42. In the absence of a control group, comparison
between observations before and after the use of a
new treatment or procedure may be misleading.
In such situations, the epidemiologist tries to utilize
a "natural" control group i.e., the one provided by
nature or natural circumstances.
If the preventive programme is to be applied to an
entire community. he would select another
community as similar as possible, particularly with
respect to frequency and characteristics of the
disease to be prevented.
Before and after comparison studies with
control
43. 1970 1971 %change
DEATHS
Victoria 564 464 -17.7
Other states 1426 1429 0.2
INJURIES
Victoria 14620 12,454 -14.8
Other states 39,980 40,396 1.0
Effect of adaptation of compulsary seat-
belt legislation in victoria comparing
with other states(where legislation not
applied)
44.
Scientifically ideal method.
Removes a large number of biases related to
selection and measurement,
Ensures temporal relationship between exposure and
outcome.
Builds up ‘faith ‘ in the findings of the study.
Advantages
45.
In many situations, rspecially those which concern
study of risk factors or prognostic factors,one can not
randomly allocate human beings into two groups.
Eg ;-smoking- lung cancer
Ethical issues.
Expensive
Long time need…..
Disadvantages