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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 |
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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 |
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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 |
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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 |
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A phase of clinical trials which is conducted after the regulatory authority has approvedregistration & marketing begins |
Phase 4 |
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________means that every patient has the same probabilityof being in the intervention or comparison groups |
Random Allocation |
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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 |
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Design issues in RCTs |
1) Eligibility criteria for inclusion/exclusion 3) Sample size calculation |
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How do we deal with selection bias in RCTs? |
Random Allocation & Allocation Concealment |
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How do we deal with measurement (performance & detecting) bias in RCTs? |
Blinding |
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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 |
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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 |
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the process in which the participants, investigatorsand/or assessors remain unaware of the intervention whichparticipants are receiving |
blinding |
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Types of blinding |
A single blind study A double blind study |
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How to deal with loss to follow-up bias? |
Intention to treat analysis |
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The number of persons needed to be treated, on average, to preventone more event |
Number Needed to Treat= 1/|RD| |
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The number of persons needed to be treated, on average, to produceone more adverse event |
Number Needed to Harm= 1/|RD| |
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Uses of NNT & NNH |
to summarize results of studies & to assist inclinical decision making |
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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 |
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Rejecting the null hypothesis when it is true is known as _____ |
type 1 error |
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Accepting the null hypothesis when it is false is known as _____ |
type 2 error |
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experiments in which groups (clusters) of subjectsrather than individual subjects are randomly allocated to interventiongroups |
Cluster RCTs |
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What type of study do we use in evaluating public health & complexinterventions delivered at a group level? |
Cluster RCTs |
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In what study are all participants randomly assigned to receive both the activeintervention & the comparison intervention? |
Crossover RCTs |
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In which type of study do subjects act as their own control? |
Crossover RCTs |
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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 |
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In which study are smaller sample sizes required since there is lessvariation in outcome within participants than between participants? |
Crossover RCTs |
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studies of studies that offer a systematicapproach to reviewing & summarizing evidence a bout a particularresearch question |
Systematic Reviews |
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How many reviewers should be involved in all stages of the review process? |
At least two |
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Which studies allow researchers to keep up to date with the constantly expandingnumber of primary studies? |
Systematic Reviews |
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Which studies critically appraise primary studies addressing the same research question, & investigate possible reasons for conflicting results among them? |
Systematic Reviews |
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Which studies provide more precise & reliable effect estimates than is possible from individual studies, which are often underpowered? |
Systematic Reviews |
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Which studiesidentify gaps in the evidence base ? |
Systematic Reviews |
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Which studies allow individuals & policy makers to make evidence based decisions & to inform the development of clinical guidelines |
Systematic Reviews |
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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 |
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Data should be extracted using __________________ to ensure that data are extractedconsistently across different studies |
a standardized form designed specifically for the review |
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Terms of assessment of study quality |
Internal validity (risk of bias) External validity (generalizability) |
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When can we calculate risk ratios, odds ratios or riskdifferences in synthesis of findings across studies? |
When study outcomes are binary |
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When isthe intervention effect quantified as the mean difference betweenthe intervention and control groups in systematic reviews? |
When study outcomes are continuous |
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Methods of synthesis of findings of systematic reviews |
Narrative Synthesis Meta Analysis |
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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) |
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Why do we use meta analysis? |
to produce a singlesummary estimate by combining the estimates reported in theincluded studies |
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How are the results of a meta-analysis displayed? |
as a forest plot |
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Biases in systematic reviews |
Language bias Publication Bias Reporting Bias |
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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 |
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In which study can results can be generalized into the general population more broadly? |
Systematic Reviews |
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Which study is considered an evidence‐based resource? |
Systematic Reviews |
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Which study is very time‐consuming? |
Systematic Reviews |
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an illness due to a specificinfectious agent or its toxic products |
a communicable disease |
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How does the chain of infection go? |
Reservoir-->Portal of Exit-->Mode of Transmission-->Portal of Entry-->Susceptible Host-->Infectious Disease |
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How can we stop the transmission of infection? |
By breaking any ink in the chain of infection |
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What's the habitat in whichthe agent normally lives, grows, & multiplies called? |
A reservoir |
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In human reservoirs, how are infectious diseases transmitted from person to person ? |
without intermediaries |
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Who are those who never experiencesymptoms despite being infected? |
Asymptomatic / Passive/ Healthy Carriers |
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Who are those who can transmit the agent during the incubationperiod before clinical illness begins? |
Incubatory carriers |
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Who are those who have recovered from their illness but remaincapable of transmitting to others?` |
Convalescent Carriers |
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Who are those who continue to harbor a pathogen? |
Chronic carriers |
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What's an infectious disease that is transmissible undernatural conditions from vertebrate animals to humans? |
Zoonosis |
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Where does Brucellosis come from? |
Cows and pigs |
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Where does Anthrax come from? |
Sheep |
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Where does the Plague come from? |
Rats |
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The portal of exit usually correspondsto ______ |
the site where the pathogen is localized |
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How do Influenza viruses & Mycobacterium tuberculosis spread? |
By the respiratory tract |
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How does Schistosomes spread? |
Through urine |
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How does Cholera spread? |
Through feces |
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Modes of disease transmission? |
Direct and indirect |
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Modes of direct disease transmission? |
Direct contact & droplet spread |
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Modes of indirect disease transmission? |
• Airborne: dust or droplets • Vehicleborne: food, water • Vectorborne (mechanical or biologic): mosquitoes or flies |
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What's the manner in which a pathogen enters asusceptible host? |
The portal of entry |
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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. |
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Why do we need to know portals of exit and entry and modes of transmission? |
to determine appropriate control measures |
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What do we call the immunity of a group or community? |
Herd immunity |
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What do we call a disease that occurs infrequently &irregularly? |
A sporadic disease |
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What do we call the constant presence and/or usualprevalence of a disease or infectious agent in a population within ageographic area? |
An endemic |
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What do we call persistent & high levels of disease occurrence |
A hyperendemic |
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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 |
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What do we call a sudden increase in the number of cases of a disease in a limited geographic area? |
An outbreak |
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What do we call an aggregation of cases grouped in place & time thatare suspected to be greater than the number expected? |
A cluster |
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What do we call an epidemic that has spread over severalcountries or continents? |
A pandemic |
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What do we call the separation, for the period of communicability of infected persons or animals from others? |
Isolation |
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What do we call the restriction of activities of healthy persons oranimals who have been exposed to an infectious person? |
Quarantine |
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What do we call the reduction of case transmission toa predetermined very low level? |
Elimination of disease |
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What do we call the termination of all transmission ofinfection by extermination of the infectious agent |
Eradication of disease |
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What do we call the process where the specific infectious agent no longer exists in the natureor in the laboratory? |
Extinction |
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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) |
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In which type of surveillance is no stimulation or feedback onreporting performance given by public health authorities? |
Passive |
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Which type of surveillance is often incomplete because there are few incentives for healthworkers to report ? |
Passive |
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In which type of surveillance do the authorities monitor health care providers' reporting frequency? |
Active |
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In which type of surveillance do public health authorities provide feedback to improve reporting performance? |
Active |
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In which type of surveillance do health care providers report disease voluntarily? |
Passive |
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In which type of reporting to we get incentives for complete reporting/ punishment for incomplete reporting? |
Passive |
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The epidemiological process in controlling communicable diseasesrequires the following information: |
• Source of infection • Mechanism of transmission • Susceptibility of the population |
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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 |
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What do we call elimination of sick animals(carriers of infectious disease)? |
Extermination |
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What do we call elimination of rats after theirsurvival from an infectious disease? |
Deratization |
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How do we administer Urgent Prevention? |
through the use of passive immunity measures(antiserum, immune globulin) or prophylactic antibiotics |
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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 |
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Aims of outbreak investigation |
1. Implement control measures 2. To improve our knowledge to prevent future outbreaks |
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Decisions to investigate a potential outbreak depend on: |
1. The disease 2. Health authorities 3. Public concerns |
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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 |
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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: |
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agraph showing the number of cases by their date of onset |
an epidemic curve |
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Examining dates & times of onset of an outbreak may suggest ______ |
a point source outbreak or infection with a characteristic incubation period |
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The age distribution of cases of an outbreak may suggest _____________ |
the vehicle of infection (e.g. milkborne outbreaks characteristically affect children rather than adults) |
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The geographical distribution of cases of an outbreak may suggest ____________ |
the source of infection & its transmission route |
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A characteristic of public health surveillance that allows identification of individual persons with disease |
Sensitivity |
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A characteristic of public health surveillance that excludes people not having the disease |
Specificity |
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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 |
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After establishing a case definition, it is important to determine thespecific information needed from surveillance to ______________ |
implement control measures, |
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Sources for gathering health data |
• Individual persons • The environment • Health‐care providers |
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the diseases or conditions to be reported when reporting is required by law |
notifiable diseases |
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After morbidity, mortality, & other relevant data about a healthproblem have been gathered, the data should be analyzed by: |
Time, place and person |
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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 |
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A problem in which reports from previous periods are held & reported all at onceduring another reporting period |
Batch reporting |
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Data & interpretations should be sent to those who: |
• Provided reports or other data • Use them for health‐related decision‐making |
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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 |
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the resistance of a host to a specific antigen |
immunity |
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a naturally existing resistance to a disease agent and does notrequire prior sensitization to disease agent |
natural immunity |
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resistance acquired by a host as a result of previous exposure(sensitization) to a disease agent |
Acquired immunity |
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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 |
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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 |
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Herd immunity of a population is determined by: |
-the ratio of resistant to susceptible members & -their distribution |
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what is the most cost‐effective public healthintervention??? |
immunization |
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Factors influencing vaccination coverage |
1) Access 2) Cost 3) People's interest (autism) |
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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 |
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How do we evaluate test accuracy? |
By comparing the results of the new index test to those of a reference (gold) standard |
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Measures used to calculate test accuracy |
Sensitivity Specificity Negative and Positive Predictive Values |
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the probability of a positivetest in people with the disease |
sensitivity |
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the probability of a negativetest in people without the disease |
specificity |
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theprobability of the person having thedisease when the test is positive |
positive predictive value |
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theprobability of the person not having thedisease when the test is negative |
negative predictive value |
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Sensitivity & specificity are determined mainly by |
the characteristics of the test itself |
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Positive & negative predictive values are determined by |
prevalence of disease in the target population |
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In a screening program where the focus is to avoid false negative results, do I want high sensitivity or high specificity? |
High sensitivity. |
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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. |
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Are screening tests used to establish a diagnosis? |
Nope, but rather thepresence or absence of an identified risk factor, & thus requireindividual follow‐up & treatment |
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A type of screening that aims to screen the whole population |
Mass screening |
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A type of screening that uses several screening tests at thesame time |
Multiple/ Multiphasic screening |
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A type of screening that aims to screen groups with specific exposures |
Targeted screening |
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A type of screening that aims to screen patients whoconsult a health practitioner for some other purpose |
Case-finding/ Opportunistic screening |
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Biases in screening programs |
Lead time bias Length bias |
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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 |
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If a test provides consistent results, it is____ |
reliable |
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If a test correctly categorizes people into groups with or without disease depending on sensitivity and specificity, it is _____ |
valid |
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Types of health care service planning |
National Strategic Evidence-Based |
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For targets to be effective, they need to be |
Achievable Realistic Monitored |
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Important issues in planning health care services |
equity Healthcare needs assessment |
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Types of evaluation of health care services |
Outcome evaluation Cost-effective evaluation Process evaluation |
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Features of global health |
Trans-national Equity for all Collaborative action |
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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 |
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In developed countries, deaths from acute infectious diseases decline, & deaths due tochronic non‐communicable diseases rise |
epidemiological transition |
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This epidemiological transition is also occurring the developing countries butat a higher speed because old disease are still there |
double burden of disease |
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A set of processes intensifying human interaction across economic,political, sociocultural, environmental & technological fields |
Globalization |