29-36 lectures Flashcards
what does a cause do?
causes an effect
what can outcomes have?
multiple outcomes
what is a cause?
an event, condition or characteristics that play an essential role in producing an occurrence of the disease
what can a causal pie model do?
used to see what exposers cause an outcome
together there exposures are sufficient to cause the outcome
what do we call a full pie?
a sufficient cause of the outcome
what is each exposure called?
a component of the sufficient cause
a component cause
how do we prevent a disease using a sufficient pie?
by removing exposures that are involved in multiple sufficent causes
what is a component cause?
necessary for the disease to occur
must be apart of every sufficient cause of the disease
how can we determine causation?
by considering if the association is a valid association
could the association that we are seeing be upto chance, bias or confounding
what happens if we have a valid association?
means it is not causal
what does BEST CDS mean?
Biological plausibility
Experimental evidence
Specificity
Temporal sequencing
Consistency
Dose-response relationship
Strength of association
what is biological plausibility?
if there is a plausable biological mechanism for the association, but epidemiology knowledge may precede knowledge on biological mechanisms
what is experimental evidence?
if there is evidence from human RCTs or animal experiments, however animal studies may not apply to humans
what is specificty?
if the exposure specificity associates with a particular outcome but not others, however it is quite common for exposures to be related to many outcomes
what is temporal sequencing?
seeing weather the exposure came before the outcome
what is consistancy?
if the finding are consistent with the findings from other studies, however there can be a number of reasons why studies might have different findings
what is dose-response relationship?
if the risk of the outcome changes with increasing or decreasing amounts of the exposure, but not all relationships are linear
what are strength of association?
the stronger the association, the less likely it is to be due to confounding or bias, however this is not always the case
what are the guildlines to see what is a causal relationship?
the BEST CDS
what is critical applause?
the process of carefully and systematically examining research to judge its trustworthiness, and its value and relevance in a particular content
what is the abstract?
provides a summary of the paper contents, a breif overveiw of the peice of work
what is the introduction?
provides beliefs story that has the aims of the study that are clearly stated
has the specific aim of the study
provides the backgrounsd to this research and what is already known on the subject
what is the methods?
used for others to carry outb the proces the same as the person that originally too the investigation
it contains the selection of participants, structure of the study, definition of exposures and outcomes measured
what is table 1?
usually the participants and their baseline characteristics
what are the results?
reporting of all the results in text, tables and figures
assessment of chance, bias and confounding
what is table 2?
usually results to interperate and relative risks
what is hazards risk the same as?
ratio risks
what is the discussion?
talks about the strength and challenges experience during the research study
what is concluision?
not always includes but usually outlines what this study adds to current knowledge, and where to from here
usually adds what the study adds to current knowledge
what is internal validity?
chance, bias, confounding
what is the reference?
list of research papers referred to in this paper
what are acknowledgements?
thanks contributors to the writing, research and funding of the research
what are conflicts of intrest?
identifies potential conflicts of interest
what are the 2 main types of reviews?
narritive and systematic
what are narritive reviews?
may be heavily influence by opinion
what are systematic reviews?
is replicable, transparent and systematic
why are systematic reviews done?
to collate evidence and synthesize thier results
what is needed in a protocol?
a specific clinical question
relevance of why we are doing this review
objectives of the study
a detailed search strategy
why do we combine results of a trial?
to generate an average result to apply a more precise outcome of the study
what is heterogeneity?
when something vaires across different groups
this is if the designs of the studies are too different
what is homogeneity?
when something is consistent across different groups
this is if the outcomes of the data are similar enough to combine to get an average result
what does sampling distribution give us?
where our true value might fall
why are forest plots called this?
because it looks likle a tree
what does the size of the dot in a forest plot mean?
the weight of the study
what are the lines of a forest plot mean?
the risk ratio and the lines represent the 95% confidence intervals
what is the width of the diamond in a forest plot mean?
the 95% confidence intervals
where is the null value in a forest plot?
the bottom of the plot
what is the limitations?
principal findings
limitations to the evidence
implications such as practice and research
what are challenges we face in the study?
getting a team of helpers
publication bias
poor quality trials/studies
heterogeneity
what are advantages we face in the study?
reproducibility
comprehensive
transparent limits
fill gaps in knowledge
forms basis for decisions
what is epidemiological surveillance?
an ongoing systematic collection, analysis interpretation and dissemination of data regarding a health event
what are elements of surveillance?
data collection - analysis - interpretation - dissemination - action
what is surveillance used for?
characterizing patterns of disease, detecting epidemics, further investigation, research, disease control programes, setting priorities, evaluation
what are the 2 types of surveillance?
indicator-based
event-base
what is passive surveillance?
is routine reporting of health data such as notifiable diseases, disease registries and hospital data
low cost, covers a wide area and data linkage
what are the limitations of passive surveillance?
under-reporting
what is active surveillance split into?
is split into serosurveillance and health survey
what is serosurveillance?
is the monitoring of the presenc eor absence of specific substances in the blood serum of a population
what is sentinal surveillance used for?
used for monitoring diseases or trend and detect outbreaks
what are the 3 types of indicator-based surveillance?
active
passive
sentinal
what is event-based surveillance?
organised monitoring of reports, media stories, rumours and other infomation about health events that could be a serious risk to public health
what is dissemination?
those who need to know, newsletter, media and reports
what is action?
when our data from our study is done and used to make a positive impact to people
what is public health?
the science and art of preventing diseases prolonging life and promoting health through organised efforts of society
what are the 3 levels of prevention?
primary, secondary and tertiary
what is a primary prevention?
interventions that attempt to prevent disease from occuring
what is a secondary prevention?
reducing impact of disease by shortening its duration, reducing severity or preventing recurrence
what is tertiary prevention?
reducing the number or impact or complications, improving rehabilitation
what are advantages for population/mass strategy?
radical, large potential for whole population, behaviourally appropriate
what are disadvantages for population/mass strategy?
small benefits to individual, poor motivation of individuals, the benefit-risk ratio may be low for individuals
what are advantages for high risk/individual strategy?
appropriate to individuals, individual motivation, clinicion motivation, favourable benefit-risk ratio for individuals
what are the disadvantages for high risk/individual strategy?
need to identify individuals, might be against population norms, can be hard to sustain behavioural change
what is the prevention paradox?
a large number of people at small risk may give rise to more cases of disease than the small number who are at high risk
what is evidence-based practice a combination of?
patient values an choices, best available evidence, and clinical expertise
what is conservation treatment?
doing nothing
if good evidence is vital, what can be used otherwise?
-ineffective treatment can be used
-give treatments for which the harms outweigh the benefits
-fail to provide effective interventions
-new expensive treatments may be no better than older cheaper ones
what makes it differcult to communicate the evidence?
-adverts backed by dubious scientific claims
-endorsements by prominent people
-scares and conspiracy theories
-the value that people place on individual stories may lead people to ignore objective evidence
what is screening?
the widespread use of a simple test for a disease in an apparently healthy population
what is a screening programme?
an organized system using a screening test among asypmathetic (healthy) people in the population to identify early cases of the disease in order to improve outcomes
what is a screening test?
a usually relatively cheap and simple, used to test large numbers of apparently healthy people to identify individuals suspected of having early disease who will then go on to have further diagnostic test in that there is greater emphasis
what is a screening test not?
a diagnostic test
a screening programme
what is the aim of screening?
To limit the consequences of disease through early diagnosis and treatment
aims to improve outcomes
what do we need to consider whe n deciding if a test is appropriate?
if the test is accurate, and if the test is acceptable and safe
what 2 things do we measure accuracy with?
sensitivity and specificity
what is sensitivity?
the proportion of people with the disease who test positive
what is specificity?
the proportion of people without disease who test negative
how do we test performance of sensitivity and specificity?
by using intrinsic properties of the test
what is PPV?
positive prediction value
what is a positive prediction value?
the proportion of people who test positive and have the disease
what is NPV?
negative prediction value
what is a negative prediction value?
the proportion of people who test negative and dont have the disease
what is PVs?
prediction values
what are prediction values?
are influenced by disease prevalence in the population of intrest, unlike sensitivity and specificity
what are 3 benefits of screening programmes?
-potential for early detection and intervention
-reassurance (true negatives)
-improved health of population
what are some harms of the screening programmes?
-increases in health inequities from unequal participation or treatment
-physical
-psycological
-financial
what is screening biased towards?
detecting slowly developing disease that may never have required treatment
what influences the spread of disease?
properties of the agent
sources of infection
biological resorviors
host factors
exposure variation
enviroment
what are the 3 segments of the epidemiology triangle?
host, enviroment, agent
what is the host?
descriptive epidemiology
what is enviroment?
enviromental investigation
what is an agent?
laboratory investigation
what does a collection of host, enviroment and agent lead to?
different factors of disease
what does host and enviroment lead to?
disease immunity
what does host and agent lead to?
transmission
what does agent and enviroment lead to?
disease survival
what are examples of infectious agents?
bacteria, viruses, fungi, protozoa and helminths
what is infection?
the entry ofn a microbiological agent into a higher order host and its multiplication with the host
what is an infestation?
only on the external surface
what is infectivity?
the ability of an organism to produce clinical symptoms and illness
what is virulence?
the ability of an organism to produce serious disease
what are some ways of transmission?
direct, indirect, airborne
what is direct transmission?
touching or inhaling infectious secretions
what is indirect transmission?
involves a vehicle
this splits into inanimate (bedding, clothes, utensils, food or water) and live (mosquitos, ticks)
what is airborne transmission?
droplet nuclei = small particles
what are outbreaks?
unexpected increase in the incidence of a disease
what is an endemic?
constant presence of a disease or infectious agent within a geographical area or population
what i holoendemic?
an intense disease all year round - children mainly infected, most adults immune
what is hyperendemic?
intense disease with time periods of no transmission - persistant disease with all age infected
what is a pandemic?
the disease affects a large number of people and crosses many international boundaries
what is an endemic disease?
a constant present in a populatioon or region, with relatively low spread
what is an epidemic disease?
the sudden increase in cases spreading through a large population
what is a pandemic disease?
the sudden increase in cases across several countries, continents or the world
what is a cluster?
a aggregation of relatively uncommon events or diseases in space and/or in time that are thought to be greater than could be expected by chance
what are clusters usually?
rare non-infectious diseases
why do we investigate outbreaks?
to stop and prevent any further illness, prevent further outbreaks from other similar sources, adress public concertns and involves the public in disease control, reduce direct and indirect costs, identify new mechanisms of transmission of known diseases, identify new or emerging disease agents
what are the 3 components that outbreak investigation is broken down into?
analytic epidemiology component
enviromental component
laboratory component
what are the 3 types of outbreaks?
common sources
propagated source (person to person)
mixed
