definitions Flashcards
(152 cards)
1
Q
what is association?
A
association is a link relationship or correlation
it is the statistical dependence between two variables
to the degree to which the rate of disease in persons with a specific exposure is either higher or lower than the rate of disease without exposure
2
Q
what is the odds ratio
A
odds of exposure in cases / odds of exposure in controls
3
Q
what things cause association?
A
charlie brown cuts coke chance bias confounding causation
4
Q
what is chance?
how to check if it is chance?
A
coincidence
calculate confidence intervals
increase the sample size
5
Q
what is bias?
A
systematic error leading to an incorrect estimate of the effect of an exposure on the development of a disease or outcome.
Defects in design cannot be overcome by increasing the sample size
6
Q
what are the two types of bias?
A
measurement bias
systematic error with the measurement technique
increasing sample size makes no difference
selection bias
this is when the people chosen for the study are characteristically biased
7
Q
what is confounding?
A
this is any factor which is believed to have a real effect on the risk of a disease
can include causal factors
or more direct unknown factors
8
Q
what are the stages at which the control might be founded?
A
- design restriction randomisation - analysis stratification standardisation regression analysis
9
Q
list the hierarchy of evidence in study design:
A
snakes rarely cook completely edible dinners, custard
systematic review RCT cohort studies case control studies ecological studies descriptive studies case reports
10
Q
what is the bradford hill criteria?
A
a group of minimal conditions needed to provide adequate evidence of a causal relationship between incidence and possible consequences
11
Q
what is the bradford hill criteria?
A
– a group of minimal conditions needed to provide adequate evidence of a causal relationship between incidence and possible consequence
12
Q
what must the relationship be if it agrees with bradford hill criteria?
A
- must be temporal
13
Q
what might the relationship be if it agrees with the bradford hill criteria?
A
- strength of effect
- consistent with other investigations
- specificity (one risk one disease)
- a biological gradient
- plausibility (means it is consistent with other knowledge)
- coherence with current thinking and previous experiments
- experimental evidence
- an analogy
- reversibility
soft crunchy seductive baked pies custard eggs also rock
14
Q
what is epidemiology?
A
the study of the distribution of health related states or events and the determinants of health relates states or events in specified populations
also the application of this study to control health problems
15
Q
what is homeopathy?
A
- based on principle of like cures like
- uses toxin that causes similar symptoms to the disease
- only 50% of cures effective
16
Q
what is a confidence interval?
A
- this is the range within which the value is expected to lie within given a degree of certainty - 95%
17
Q
what is a P value?
A
- the probability that results are simply due to chance
. p < 0.05 = 95% certain results not due to chance
18
Q
what is bias?
A
cannot be controlled by analysis/ sample size
- measurement bias
- selection bias
19
Q
what is the MMR vaccine?
A
this combines measles mumps and rubella
- 2 stages
prevents deaths from mumps which causes meningitis
the rubella vaccine stops kids catching rubella from their mothers
20
Q
why was the MMR vaccine taken away?
A
- studies based on the MMR vaccine made people believe that side effects like autism were caused by the vaccine
- there was no causal link
- the MMR vaccine was taken away
- deaths went up
- returned due to recognition of the flawed causality
21
Q
what is human generation time?
A
- this is the time taken from our birth to a female producing a child
around 25+ years for humans - much lower for viruses and bacteria
22
Q
what are the origins of human infection?
A
- ancestors
- wildlife
- livestock
23
Q
what are changes in the world leading to spread of infectious disease?
A
- increasing population
more dense faster transmission of disease
increase in rate of evolution - movement of people by planes
influenza H1N1 spread like this
due to migration of people
24
Q
what is epidemiology?
A
- based on ability to quantify the occurrence of disease in populations
- needs definition of word case:
- case = person with disease, heath disorder, or suffering from event of interest
25
what is prevalence
frequency of disease in a population at a point in time
number of cases / number of people in the population
measures the burden of a disease
26
what is incidence?
the number of new cases of a disease within a specified time interval
Incidence measures NEW CASES while prevalence measures ALL CASES
prevalence is dependent upon incidence
27
how to estimate incidence ?
- define the time period
- define the denominator (how many people are at risk)
- come up with a good test to define a true case
(eg. blood test for ebola)
28
how does incidence influence policy makers
- it affects if the country says there is an outbreak or not
29
what is mortality?
mortality is the number of deaths from a specify disease or condition
if mortality = incidence
then the epidemic is stable
30
what is the mortality equation
deaths from disease in time period / population at beginning of start of time period
31
what are disadvantages of mortality going down?
- the number of deaths decreases so people are alive for longer therefore can pass the disease on quicker
- the prevalence will increase as more people catch the disease but less people are dying
32
what is the difference between morbidity and mortality?
- morbidity is the state of being diseased
| - mortality is number of people who have actually died from the disease
33
how to measure mortality?
- number of deaths per 1000
- leading causes of death are heart disease stroke res HIV and COPD
- swaziland is highest
- in 3rd world it is mainly malnutrition
34
how to measure morbidity?
- scores are assigned to ill people
eg glasgow coma scale, PIM2, SOFA
- used to compare patients
- helps decide medication
35
what are the leading causes of infectious disease?
- lower res infection
- HIV
- diarrhoea
- TB
- malaria
- measles
Little happy dark toads make merry
36
why is mortality rate important
- effectiveness of the health system
| - policy makers can decide actions based on these decisions
37
```
what is H1N1
SARS
west nile virus
HIV
MERS
ebola
```
- swine flu
- severe acute resp syndrome
- mosquito USA
- chimpanzee, evolution – multiple introduction into humans
- middle east resp syndrome
- west africa
38
what is the basic reproductive number?
- R0
- average number of secondary cases from the emergence of a single primary case Is known as the basic reproductive number
- if the number is less than 1 it will get extinct
- if the number is more than one it will be an epidemic
39
what factors affect R0?
- Duration of incubation period
- Peak infectiousness
- How quickly infectiousness decays
- Is acquried immunity important
40
what is the effective reproductive number?
- the number of infections caused by each new case occurring at a time
41
what happens with the emergence of a new disease?
- indication
- identify the agent
- determine the route of transmission
- identify clinical algorithms
- put in place communication systems
- public health info
42
what is SAR?
| 2003
severe acute respiratory syndrome
started from bats
- central asia
43
west nile virus?
| 1999
- originates from birds
- high infection rate
- there is a vaccine coming soon
44
HIV 1
| 1982
- caused by RNA virus
- epidemics caused by this
- integrase inhibators used (effective )
- vaccine is not successful
due to RNA viruses mutating and RNA having no proof reading mechanisms
45
malaria
- Generation of genetic variability mutation and recombination of different gametes
- plasmodium virus has lots of different proteins therefore hard to make a vaccine
46
MERS virus
middle east resp syndrome
- origin from camels
- high incidence in middle east
47
Ebola epidemic
- slow transmission
- symptoms appear before becoming infectious so patient is placed in isolation
- spread via body fluids
- lots of health workers infected
48
zika virus
- from monkeys
- south america
- spread around the world really quickly
- mosquitos
- 1/ 100 risk for pregnant mothers in first trimester
- related to yellow fever and dengue
- STI
49
how does the rate of infection a disease change?
- new infections increases slowly
- then exponential
- eventually tails off
- then rises again
- humans tackling disease brings it down as well
- however new mutation and selective advantage also causes a new epidemic .
50
what are the policy objectives for influenza?
- minimise morbidity and mortality with the fixed budget
- buy time before vaccine developed
- minimise effect on economy
- minimise peak prevalence
51
what are the major neglected tropical diseases?
- protozoan infections
sleeping sickness
- helminth infections
soil transmitted diseases
- bacterial infections
- leprosy
- trachoma
52
when was first AIDs case identified?
- 1959 in the UK
- 1980 in LA
- from 1983 over 100 cases
53
what groups were tested in response to HIV?
- men having frequent male male sexual contact
- IDU users
- heterosexuals
gay sex was the cause
54
- how was the hypothesis of HIV tested?
- men with the conditions were interviewed for all the possible causes
- results showed that having lots of sexual partners resulted in HIV
- common factor between young gay men
55
what is a case controlled study?
- a case control study sets out a known outcome and compares individuals and determines what connects them
always retrospective because you start with the outcome and then look back
56
how are case controlled studies designed?
- always retrospective
- helps determine is the exposure is associated with the outcome
- identify the cases and controls (specific)
- look back and see which subjects in each group had the exposure
57
how did the incidence and prevalence of HIV change?
- graph on aishas notes
- basically incidence does not go up or down a lot
- but prevalence increases
- prevalence increased even more when there was medication meaning people with HIV survive
58
is the HIV epidemic stable?
- 2.7 million new infections a year
- 2 million deaths a year
- epidemic is quite stable
59
what is ART?
anti retroviral treatment
60
what is ARTs effect on mortality, incidence and prevalence
- mortality reduces and people live for longer
- mortality goes down meaning more people transmit the virus to other people and their babies
- prevalece increases as less people are dying
- incidence might decrease due to the use of ART
61
what are the steps of tackling HIV?
- money is a problem
3500 in uk new patients each day
- giving mothers treatment before birth will help stop virus being spread
62
what is the classification of disease?
- communicable
- non communicable
- injuries
63
what is epidemiological transition?
- changes in the levels and the causes of mortality
- overall there is a decline in total morality
- this means there is an increase in people suffering from chronic non communicable diseases (cancer, cardiovascular disease, chronic resp disease)
- factors affecting health and disease includes demographic, socioeconomic, tech, cultural, environmental, biological changes
- emergence of new infectious diseases happens
changes in disease are mainly due to demographics and epidemiology
64
what is demographic transition
| what is epidemiological transition?
demographic - from high birth and death rates to low birth rates and death rates
epidemiological - when infectious diseases are replaced by man made and degenerative diseases
65
what is epitransition?
these are disease patterns that move from being infection to chronic conditions
66
info about cancer?
- developing countries have a greater mortality of cancer because there are less resources
- males - lung and prostate
- women - breast and cervical
cancer is heterogenous
67
what are the differences between men and women in terms of getting cancer?
- in men the most frequent cancer is lung cancer
- in west africa however lots of men die of liver cancer
- for women in developed countries greatest cause of death is lung cancer (not breat due to screening ect)
- however in developing countries the greatest risk is breat cancer
68
what are cancer risk factors generally?
- smoking
- alcohol
- unsafe sex
- obesity
- contaminators injections drugs
- air pollutants
- smoke from fuel
69
what agents are related to cancer deaths?
where is this more common
- hepatitis (liver)
- H pylori (stomach)
- HPV (cervical cancer)
- EBV (lymphomas)
this is much more common in developing countries rather than developed countries
70
what is an example of demographic change?
- diet is a factor
| - what has happened is
71
what is an example of epidemiological change?
in developed countries the main causes of death are things like heart disease
stroke
COPD and resp diseases where as in developing countries the main cause of death is thing like infection
72
what is the transition of heart disease? (CVD)
| what is the mortality like in high income and low income countries
- increasing in prevalence
- however mortality is decreasing
- high income countries = the mortality is quite stable
- low income countries = it is increasing
73
why is death rate better than death number?
this is because rate is the number of deaths in a population scaled to time
so it is less likely to be mis interpreted
74
what characteristics of a person might change whether or not you develop CHD?
age is a big factor
- numbers increase with age for CHD
- however past 80 it stops increasing because people have often died by that age , not that they are not affected
in a graph this should by shown with death rate not the number
- often lower in women however after menopause gets similar
- for white and black people at first they are similar but then the rates for black males increases above white males
75
what is the distribution of CVD like in USA, europe, africa
USA 33%
Europe 60%
Africa 10%
is the difference in distribution due to environment or genetics
- a trial could be carried out on migrants - it shows that it is mainly environment to blame
76
what are established risk factors for CHD?
- cholesterol levels
- high blood pressure
- smoking
- body weight
- reduced physical activity
77
what is a good indicator of elevated risk of CHD?
- cholesterol is a good predictive marker
- it is well measured
- however it is difficult to attribute high cholesterol to CHD because it is a multifactorial disease
78
what affects high blood pressure rates?
- increase with age might result in increase in high blood pressure
- lifestyle factors especially salt in diet are crucial in explaining the differences in population BPs
- some races are also more hypertensive than other races
79
how does hypertension or high cholesterol relate to increase risk of CHD?
what are benefits of this correlation
- increase in a gradient way
- each unit increase for blood pressure or cholesterol level means risk of CHD also increases
- means that using the info you can focus at the people who are at most high risk
80
what are the negatives of only focussing on high risk patients?
- only focussing on people just above the cut off might cause some problems
- this might ignore those who are below the cut off
- there should instead be a focus on everyone decreasing their cholesterol and blood pressure
81
how has the rate of smoking changed as a risk factor of CHD?
- huge risk factor
- overall rates have decreased
- but the decrease is slow
- in developing countries the rate is increasing
82
how is obesity changing?
- obesity is increasing
- in america is is rapidly increasing
10% -30%
83
how is physical inactivity changing?
- worldwide
- increased modernisation in terms of transport ect
- sedentary life style
84
what is public health?
this is the science and the art of preventing disease, prolonging life, and promoting health through efforts of society
85
what are the three main domains of public health?
- health improvement
- health protection
- health services
i poke sloths
86
what is health?
health is a resource for everyday life, not the objective of living. Health is a positive concept emphasising social and personal resources as well as physical capacities
87
what are health indicators?
- Life expectancy at birth
- socioeconomic status
- what is the leading cause of death
88
why is life expectancy an indicator of health?
- increased from 1970 due to demographical transition
- result of increase in knowledge and sanitation
- improved socioeconomic conditions
- sometimes even split in LE within one country eg. north and south
89
do males or females have a higher life expectancy ?
- females have a higher life expectancy to males
90
what factors can you not change that effect your likelihood of death?
- age
- sex
- ethnicity
- genetics
- stress
91
what does likelihood of smoking depend on?
- ethnicity, gender, education
92
what does smoking account for?
- more than 1/3 of resp diseases
- more than 1/4 of cancer deaths
- more than 1/7 of CVD deaths
93
what are drinking rates in rich and poor?
| young and old?
in the rich the drinking rates are more than the poor
| - young people drink less days a week but they drink more
94
how have the levels of sexually transmitted diseases changed over time?
- levels increased after war
- levels dropped again after new antibiotics introduced
- levels rose in 60s and 70s due to the attitude change
- after HIV spread the drop is dramatics
- but after ART the levels rise again
95
what overall factors affect the population?
- health behaviours
- clinical care
- socioeconomic factors
- physical environment
96
what is health promotion?
- health promotion is the process of enabling people to increase control over and to improve their health
- action is taken towards social, economic and environmental quality
97
what is health improvement?
- an approach to action for health that takes account of
- the broad definition of health
- the scope of prevention
- limitations of the health services
- role of individuals
- focus is on health not disease
98
what does health promotion involve?
- clinical interventions
screening
- knowledge transfer and health literacy
promoting info about smoking, healthy eating, exercise promotion
- healthy public policy
legal measures to make health easier
policies regarding the wider determinants of health
- community development
radical - groups setting their own agenda
partnerships with public, private organisations to create sustainable action
99
what are the levels of prevention of disease?
| and what do each of them do?
- primordial
prevention of factors which might promote the emergence of lifestyles which contribute to increased disease
- primary
these are actions to prevent to onset of disease , to limit exposure to risk factors
- secondary
to halt progression of the disease once it is already established
- tertiary
this is the rehabilitation of people with established disease
100
what are the approaches to disease prevention?
- high risk approach
| - population approach
101
what is the high risk approach?
- this is when those who are in special need are targeted
- then the exposure is controlled
- there is protection against the effect of exposure
- there is also screening amongst minority groups for specific disorders
102
what is the population approach?
- this starts with the occurrence of common diseases and their exposures and how these things affect the behaviour of society as a whole
103
what are the strengths and weaknesses of the high risk approach?
```
- strengths =
effective
efficient
appropriate to the individual
easy to evaluate
```
- weaknesses=
- misses quite a lot of disease
- the risk prediction is not accurate
- there is difficulty in cost of screening
- hard to change individual behaviours
104
what are the strengths and weaknesses of the population approach?
strengths =
- radical
- large potential for the whole population
- it is good to change behaviours
weaknesses =
- small advantage to the individual
- poor motivation of subject
- poor motivation of physician
- benefit : risk ratio might be questioned
105
what is the population paradox?
- this reiterates that targeting those who have a small risk helps to act as a preventive measure
- instead of just targeting the small population who have a large risk
106
what policies focus on health promotion?
- the wanless report - focusses on prevention and the wider determinants of health
also takes into account cost effectiveness
107
what are health priorities in the UK?
- smoking
- alcohol
- obesity
- sexual health
- teenage pregnancy
- mental health
108
what is the national alcohol strategy?
- end sales of the cheapest alcohol
- strengthen the ban on irresponsible promotions in pubs and clubs
- improve education
- promote drink safety
109
what were the WHO's commission in the social determinants meant to achieve?
- improve conditions of normal life
- tackle to unfair distribution of power, money and resources
- measure the problem, evaluate action, and develop a work force , raise public awareness
110
what are the 6 policies of the marmot review?
- give each child the best start in life
- enable all children to maximise their capabilities
- create fair employment
- ensure a healthy standard of living for all
- create and develop a healthy and sustainable place and community
- strengthen ill health prevention
111
what do descriptive studies look at ?
- they describe the distribution of factors or disease in relation to
- person
- place
- time
112
what is routine data?
- routine data is collected and recorded in an ongoing systematic way often for legal purposes
- it is conducted without any specific question at the time
113
what are advantages and disadvantages to routine data collection?
- advantages=
- cheap
- already collected
- standardised collection procedure
- available for the past years
- disadvantages=
- might not answer the question
- variable quality
- variable validity
- needs careful interpretation
114
what are examples of health outcome data?
- mortality
- cancer
- notification of infectious disease
- termination of pregnancy
- congenital anomalies
- hospital episode stats
- GP data
- road traffic accidents
115
what are examples of cross sectional studies?
- eg. census every 1- years
| - NHS staff survey
116
what are advantages and disadvantages of cross sectional studies?
advantages
- useful for health care providers to allocate resources efficiently and plan effective prevention
- describe the status of individuals with respect to absence or presence of exposure or disease
disadvantages
- cannot distinguish whether exposure preceded disease or the other way around
117
how to measure rates of mortality?
- local registers of birth and death
- death certificate
- published tables
118
what are cancer registrations?
- voluntary notifications to the local cancer registry
- this is now a national system
- this is good for both incidence and for survival information
119
what are infectious disease notifications?
- reported by doctors
- incidence of disease
- this includes food poisoning, meningitis,,TB and the plague
120
what is the quality and outcomes framework?
- the quality and outcomes framework is a component of the new general medical services contract for GPs
121
what is an episode?
the time spent in the care of one consultant
122
what is admission?
- a patients stay in the hospital
123
what is a case control study?
- case control studies are commonly used in epidemiology
- they work by needing a case with a disease and a factor which is exposed
- eg. is there an association between frequent use of a mobile phone and brain cancer
- the comparison happens between the control and those actually exposed
124
how are the controls selected?
- this is the most important part of the design of case control studies
- controls must be subjects who are free of the disease during the same time the cases were identified
- they should represent the population of individuals who would have been identified
125
what are the sources of the controls?
- neighbourhood
- friends
- hospital
126
advantages and disadvantages of case control studies?
- advantages?
- good for rare disease
- quick and cost effective
- can investigate lots of exposures?
- disadvantages?
- problems of selection of controls (selection bias)
- uncertainty of exposure time relationship
- poor for rare exposures
- cannot calculate incidence
127
what is a cohort?
- a cohort is a group of people with something in common
| eg. everyone registered with the same GP
128
advantages of cohort studies?
- able to look at multiple outcomes
- able to follow the natural history of the disease
- incidence can be calculated
129
disadvantages of cohort studies?
- inefficient for studying rare diseases
| - expensive and time consuming
130
what are the two types of cohort study?
- retrospective- routine data
- look at relationship between exposure and outcome
- quicker way of doing cohort study
- prospective
- compares rates of disease in exposed group and unexposed group
- looking at outcome after passed time
131
what is the standardised mortality ratio?
- one method for comparing rates of mortality is the standardised mortality ratio
- the standard morality ratio is a rate ratio adjusted for age
- it represents the ratio of the number of observed deaths to the number that would be expected
- it is very common for standard mortality ratio to be adjusted for age and sex
132
what is bias?
- a systematic error in design, conduct or analysis of a study which produces a mistaken estimate of treatment effect
133
what is confounding?
- this is when a variable or a factor is related to both the study variable and the outcome so the effect of the study variable on the outcome is distorted
134
what is a clinical trial and why is it unique?
- this is planned in humans - it is designed to measure the effectiveness of an intervention
- the intervention is normally a new drug
- epidemiological studies are different because they are observational meaning the investigator measures what happens but does not control it
- clinical trials are experimental
135
what are features of a clinical trial?
- experimental study
- contains a control group
- prospective means the participants are followed
- must be the same time period
- participants must be randomised
- the participants and the researcher should be unaware of the drug and control group (double blinding)
136
what things must be done in clinical trials?
- define your intervention
- define comparator (maybe placebo, alternative treatment, standard of care)
- define the inclusion criteria
- define exclusion criteria
137
what is a control group?
why is a control group needed?
- the study participants who do not receive intervention
- the control group must be included otherwise you cant be sure why the outcome happened
- the control group might be given a placebo or inactive substance
138
why is randomising important?
- this ensures balance
- removes allocation bias
- without randomisation it is likely that the investigator will choose
different patients for each group
139
what are the three types of randomisation?
- block randomisation
- stratification
- minimisation
140
why is blinding important?
- this means the patient does not know whether they are getting the new treatment or they are getting the control - the researcher also does not know
- this is in order to prevent bias
- this gets rid of the placebo effect
141
why is ethics important in clinical trials?
all clinical trials have to be
registered (rolling)
reviewed by independent scientific committee (Roger)
approved Research Ethics Committee (appreciates)
adhere to government and international guidelines
(apples)
rolling roger appreciates apples
142
what is an independent data monitoring committee?
- this is a group of independent researchers who can check progress during the trial
they sometimes unblind the test to see if there is a big difference
143
consent in clinical trials?
every one must supply consent before attending and can pull out at any time
144
how does analysis of the trial happen?
- at the end of the trial the results will be analysed
| - the outcomes are presented in terms of efficacy and effectiveness
145
what are the outputs of the trial?
```
- the experimental event rate
(incidence in the intervention arm)
- the control event rate (incidence in control arm)
- absolute risk reduction
- number needed to treat
```
146
how should trials be reported?
- should be reported according to CONSORT
| (consolidated standards of reporting trials ) guidelines
147
how many phases of clinical trials are there?
- there are 4 stages
148
what are phase 1 trials for
- test the safety of the trial
| - involves only a small group of healthy volunteers
149
what are phase 2 trials for
- larger group of people who actually have the disease
- normally a few 100
- also looks at safety
150
what are phase 3 trials for
- tests the new treatment in a larger group of people
- compares the drug with a placebo
- looks at side effects
- several thousand patients involved
- patients are recruited from multiple locations
-
151
what are phase 4 trials for
- this is done after the treatment has been marketed
| - to see any side effects and the drugs effects in various populations
152
what is screening?
- the practise of investigating apparently healthy individuals
