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153 Cards in this Set

  • Front
  • Back

What are research studies that prospectively assign groups ofhumans to one or more health‐related interventions to evaluate theeffects on health outcomes?

Clinical Trials

A phase of clinical trials which tests a drug or a vaccine in a small group of humans todetermine its safety, mode of action, dosage, & route of administration

Phase 1

A phase of clinical trials whichexamines the efficacy of a drug or a vaccine in a small groupof patients in comparison to existing regimens

Phase 2

A phase of clinical trials which provides complete assessment of a drug or a vaccine safety &efficacy in larger numbers of patients with the disease or condition ofinterest; it uses random allocation to the intervention & comparisongroups

Phase 3

A phase of clinical trials which is conducted after the regulatory authority has approvedregistration & marketing begins

Phase 4

________means that every patient has the same probabilityof being in the intervention or comparison groups

Random Allocation

The goals of random allocation

ensures that the groups are comparable for bothknown & unknown confounders,

& that any differences betweengroups are due to chance but not bias

Design issues in RCTs

1) Eligibility criteria for inclusion/exclusion
2) Definition of intervention & control groups

3) Sample size calculation

How do we deal with selection bias in RCTs?

Random Allocation & Allocation Concealment

How do we deal with measurement (performance & detecting) bias in RCTs?


A method of generating a sequence that ensuresrandom allocation between the intervention & comparison groups of astudy without revealing this to study subjects or researchers

Allocation Concealment

the biased assessment of outcome, where theoutcome assessor or the participant is more or less likely to report aspecific outcome in the intervention & comparison groups dependingon their beliefs or preferences

Detection Bias

the process in which the participants, investigatorsand/or assessors remain unaware of the intervention whichparticipants are receiving


Types of blinding

A single blind study

A double blind study

How to deal with loss to follow-up bias?

Intention to treat analysis

The number of persons needed to be treated, on average, to preventone more event

Number Needed to Treat= 1/|RD|

The number of persons needed to be treated, on average, to produceone more adverse event

Number Needed to Harm= 1/|RD|

Uses of NNT & NNH

to summarize results of studies & to assist inclinical decision making

How do we interpret observed differences in RCTs?

1.Chance reflection of the sampling variation & randomization procedure

2. True differences due to effectof the intervention

3. Differences in characteristics between initial composition of the groups

4. Differences between the management of the groups during the trial

Rejecting the null hypothesis when it is true is known as _____

type 1 error

Accepting the null hypothesis when it is false is known as _____

type 2 error

experiments in which groups (clusters) of subjectsrather than individual subjects are randomly allocated to interventiongroups

Cluster RCTs

What type of study do we use in evaluating public health & complexinterventions delivered at a group level?

Cluster RCTs

In what study are all participants randomly assigned to receive both the activeintervention & the comparison intervention?

Crossover RCTs

In which type of study do subjects act as their own control?

Crossover RCTs

What's that stage in the crossover RCT when the active treatment iswithdrawn so that its effects disappear & the subject’s characteristics return to theirbaseline state?

washout phase

In which study are smaller sample sizes required since there is lessvariation in outcome within participants than between participants?

Crossover RCTs

studies of studies that offer a systematicapproach to reviewing & summarizing evidence a bout a particularresearch question

Systematic Reviews

How many reviewers should be involved in all stages of the review process?

At least two

Which studies allow researchers to keep up to date with the constantly expandingnumber of primary studies?

Systematic Reviews

Which studies critically appraise primary studies addressing the same research question, & investigate possible reasons for conflicting results among them?

Systematic Reviews

Which studies provide more precise & reliable effect estimates than is possible from individual studies, which are often underpowered?

Systematic Reviews

Which studiesidentify gaps in the evidence base ?

Systematic Reviews

Which studies allow individuals & policy makers to make evidence based decisions & to inform the development of clinical guidelines

Systematic Reviews

Steps in conducting systematic reviews

1)Formulating a review question and defining inclusion criteria

2)Identifying relevant studies

3)Extracting data and assessing study quality

4)Analyzing data

5)Presenting results

Data should be extracted using __________________ to ensure that data are extractedconsistently across different studies

a standardized form designed specifically for the review

Terms of assessment of study quality

Internal validity (risk of bias)

External validity (generalizability)

When can we calculate risk ratios, odds ratios or riskdifferences in synthesis of findings across studies?

When study outcomes are binary

When isthe intervention effect quantified as the mean difference betweenthe intervention and control groups in systematic reviews?

When study outcomes are continuous

Methods of synthesis of findings of systematic reviews

Narrative Synthesis

Meta Analysis

When do we use narrative synthesis?

when the number of includedstudies is too small or when the included studies are using differentoutcome measures (OR, RR, etc)

Why do we use meta analysis?

to produce a singlesummary estimate by combining the estimates reported in theincluded studies

How are the results of a meta-analysis displayed?

as a forest plot

Biases in systematic reviews

Language bias

Publication Bias

Reporting Bias

How do we check for reporting bias?

By using a funnel plot - If reporting bias is present, it will lead to a symmetrical appearance of afunnel plot

In which study can results can be generalized into the general population more broadly?

Systematic Reviews

Which study is considered an evidence‐based resource?

Systematic Reviews

Which study is very time‐consuming?

Systematic Reviews

an illness due to a specificinfectious agent or its toxic products

a communicable disease

How does the chain of infection go?

Reservoir-->Portal of Exit-->Mode of Transmission-->Portal of Entry-->Susceptible Host-->Infectious Disease

How can we stop the transmission of infection?

By breaking any ink in the chain of infection

What's the habitat in whichthe agent normally lives, grows, & multiplies called?

A reservoir

In human reservoirs, how are infectious diseases transmitted from person to person ?

without intermediaries

Who are those who never experiencesymptoms despite being infected?

Asymptomatic / Passive/ Healthy Carriers

Who are those who can transmit the agent during the incubationperiod before clinical illness begins?

Incubatory carriers

Who are those who have recovered from their illness but remaincapable of transmitting to others?`

Convalescent Carriers

Who are those who continue to harbor a pathogen?

Chronic carriers

What's an infectious disease that is transmissible undernatural conditions from vertebrate animals to humans?


Where does Brucellosis come from?

Cows and pigs

Where does Anthrax come from?


Where does the Plague come from?


The portal of exit usually correspondsto ______

the site where the pathogen is localized

How do Influenza viruses & Mycobacterium tuberculosis spread?

By the respiratory tract

How does Schistosomes spread?

Through urine

How does Cholera spread?

Through feces

Modes of disease transmission?

Direct and indirect

Modes of direct disease transmission?

Direct contact & droplet spread

Modes of indirect disease transmission?

• Airborne: dust or droplets

• Vehicleborne: food, water

• Vectorborne (mechanical or biologic): mosquitoes or flies

What's the manner in which a pathogen enters asusceptible host?

The portal of entry

What does the susceptibility of a host depend on?

1)Genetic factors

2)Host immunity

3)Nonspecific factors that affect an individual's ability to resist infection includethe skin, mucous membranes, gastric acidity, cilia in the respiratory tract, & thecough reflex, nutritional status, etc.

Why do we need to know portals of exit and entry and modes of transmission?

to determine appropriate control measures

What do we call the immunity of a group or community?

Herd immunity

What do we call a disease that occurs infrequently &irregularly?

A sporadic disease

What do we call the constant presence and/or usualprevalence of a disease or infectious agent in a population within ageographic area?

An endemic

What do we call persistent & high levels of disease occurrence

A hyperendemic

What do we call a sudden increase in the number of casesof a disease above what is normally expected in that population inthat area?

An epidemic

What do we call a sudden increase in the number of cases of a disease in a limited geographic area?

An outbreak

What do we call an aggregation of cases grouped in place & time thatare suspected to be greater than the number expected?

A cluster

What do we call an epidemic that has spread over severalcountries or continents?

A pandemic

What do we call the separation, for the period of communicability of infected persons or animals from others?


What do we call the restriction of activities of healthy persons oranimals who have been exposed to an infectious person?


What do we call the reduction of case transmission toa predetermined very low level?

Elimination of disease

What do we call the termination of all transmission ofinfection by extermination of the infectious agent

Eradication of disease

What do we call the process where the specific infectious agent no longer exists in the natureor in the laboratory?


Epidemiological methods to monitor &control communicable diseases

1. Active & passive disease surveillance

2. Disease & outbreak investigations

3. Contact tracing & follow‐up of those who have come into contactwith infected persons

4. Prevention of disease transmission

5. Education

(She is pretty-freaking educated)

In which type of surveillance is no stimulation or feedback onreporting performance given by public health authorities?


Which type of surveillance is often incomplete because there are few incentives for healthworkers to report ?


In which type of surveillance do the authorities monitor health care providers' reporting frequency?


In which type of surveillance do public health authorities provide feedback to improve reporting performance?


In which type of surveillance do health care providers report disease voluntarily?


In which type of reporting to we get incentives for complete reporting/ punishment for incomplete reporting?


The epidemiological process in controlling communicable diseasesrequires the following information:

• Source of infection

• Mechanism of transmission

• Susceptibility of the population

Communicable disease prevention or controlmeasures

• Measures to eliminate or decontaminate the source of infection

• Measures to stop the mechanism of transmission of infection

• Measures to reduce the susceptibility of the population to a certaincommunicable disease

What do we call elimination of sick animals(carriers of infectious disease)?


What do we call elimination of rats after theirsurvival from an infectious disease?


How do we administer Urgent Prevention?

through the use of passive immunity measures(antiserum, immune globulin) or prophylactic antibiotics

How are outbreaks discovered?

• Hospital infection control practitioners (e.g. nosocomial or hospital-acquired infections)

• Alerts from medical practitioners (e.g. specialists & laboratories)

• Patients or other community members

• Review of surveillance data

Aims of outbreak investigation

1. Implement control measures

2. To improve our knowledge to prevent future outbreaks

Decisions to investigate a potential outbreak depend on:

1. The disease

2. Health authorities

3. Public concerns

Steps of an outbreak investigation & management

1. Establishing that an outbreak exists

2. Confirming the diagnosis

3. Find cases systematically & record information

4. Describing the outbreak

5. Generating hypothesis regarding the cause of the outbreak

6. Testing the hypothesis

7. Implement control & prevention measures

8. Initiate or maintain surveillance

9. Disseminate findings to local authorities

When investigating an outbreak, what should data collection include?

A. Identifying information:

B. Demographic information:

C. Clinical information

D. Risk factor information

E. Reporter information:

agraph showing the number of cases by their date of onset

an epidemic curve

Examining dates & times of onset of an outbreak may suggest ______

a point source outbreak or infection with a characteristic incubation period

The age distribution of cases of an outbreak may suggest _____________

the vehicle of infection (e.g. milkborne outbreaks characteristically affect children rather than adults)

The geographical distribution of cases of an outbreak may suggest ____________

the source of infection & its transmission route

A characteristic of public health surveillance that allows identification of individual persons with disease


A characteristic of public health surveillance that excludes people not having the disease


The criteria that are applied to determine disease ‘importance’ in surveillence

1) Public health importance

2) Ability to prevent, control or treat the problem

3) Capacity of health system to implement control measures

After establishing a case definition, it is important to determine thespecific information needed from surveillance to ______________

implement control measures,

Sources for gathering health data

• Individual persons

• The environment

• Health‐care providers

the diseases or conditions to be reported when reporting is required by law

notifiable diseases

After morbidity, mortality, & other relevant data about a healthproblem have been gathered, the data should be analyzed by:

Time, place and person

Common causes of artifactual changes in disease incidence or prevalence

1) Changes in local reporting procedures

2) Changes in case definition

3) Increased health‐seeking behavior

4) Increase in diagnosis

5) Increased physician awareness of the condition

6) Outbreak of a similar disease, maldiagnosed as disease of interest

7)Lab error

8) Batch reporting

A problem in which reports from previous periods are held & reported all at onceduring another reporting period

Batch reporting

Data & interpretations should be sent to those who:

• Provided reports or other data

• Use them for health‐related decision‐making

1. Building healthy public policy

2. Creating supportive environments

3. Strengthening community action

4. Developing personal skills

5. Reorientation of health services

These are???

Ottawa's key components for health promotion

the resistance of a host to a specific antigen


a naturally existing resistance to a disease agent and does notrequire prior sensitization to disease agent

natural immunity

resistance acquired by a host as a result of previous exposure(sensitization) to a disease agent

Acquired immunity

resistance developed in response to stimulus by an antigen(infecting agent or vaccine) and usually characterized by the presence of antibodyproduced by the host

active immunity

immunity given by an antibody produced in another host &acquired naturally by an infant from its mother or artificially by administration of anantibody‐containing preparation (antiserum or immune globulin)

passive immunity

Herd immunity of a population is determined by:

-the ratio of resistant to susceptible members & -their distribution

what is the most cost‐effective public healthintervention???


Factors influencing vaccination coverage

1) Access

2) Cost

3) People's interest (autism)

Why do we always introduce new tests into clinical practice?

• Reduce the risk

• Less invasive or painful for the patient

• Cheaper, quicker or easier to perform

• More accurate than existing tests

How do we evaluate test accuracy?

By comparing the results of the new index test to those of a reference (gold) standard

Measures used to calculate test accuracy



Negative and Positive Predictive Values

the probability of a positivetest in people with the disease


the probability of a negativetest in people without the disease


theprobability of the person having thedisease when the test is positive

positive predictive value

theprobability of the person not having thedisease when the test is negative

negative predictive value

Sensitivity & specificity are determined mainly by

the characteristics of the test itself

Positive & negative predictive values are determined by

prevalence of disease in the target population

In a screening program where the focus is to avoid false negative results, do I want high sensitivity or high specificity?

High sensitivity.

In a test where the focus is to avoid false positives because treatment is very harmful and invasive, do I want high sensitivity or high specificity?

High specificity.

Are screening tests used to establish a diagnosis?

Nope, but rather thepresence or absence of an identified risk factor, & thus requireindividual follow‐up & treatment

A type of screening that aims to screen the whole population

Mass screening

A type of screening that uses several screening tests at thesame time

Multiple/ Multiphasic screening

A type of screening that aims to screen groups with specific exposures

Targeted screening

A type of screening that aims to screen patients whoconsult a health practitioner for some other purpose

Case-finding/ Opportunistic screening

Biases in screening programs

Lead time bias

Length bias

The screening program (which is more likely to detect slower progressing diseases which have better prognosis than aggressive diseases) may thus falselyappear to improve survival in patients lessaggressive disease as compared to patientswith more aggressive disease

Length bias

If a test provides consistent results, it is____


If a test correctly categorizes people into groups with or without disease depending on sensitivity and specificity, it is _____


Types of health care service planning




For targets to be effective, they need to be




Important issues in planning health care services


Healthcare needs assessment

Types of evaluation of health care services

Outcome evaluation

Cost-effective evaluation

Process evaluation

Features of global health


Equity for all

Collaborative action

a study which used various data sources & techniques to estimatethe numbers of deaths and disability adjusted life years (DALYs)attributable to specific causes

The Global Burden of Disease (GBD) study

In developed countries, deaths from acute infectious diseases decline, & deaths due tochronic non‐communicable diseases rise

epidemiological transition

This epidemiological transition is also occurring the developing countries butat a higher speed because old disease are still there

double burden of disease

A set of processes intensifying human interaction across economic,political, sociocultural, environmental & technological fields