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RespoEpiDecko Flashcards

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1
Q

Hygiene Hypothesis
What did the Finnish “conscript” study show with regards to asthma prevalence between 1960 - 1980 in young men? Haahtela et al

A

Those conscripted had medical screening.

Prevalence of asthma went up from 0.1%-1.8% “at or before screening”

Prevalence (unsurprisingly) went up in those exempted from joining the army

BUT prevalence in those “discharged” because their asthma affected their ability to be in the army also went up.

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2
Q

Hygiene Hypothesis

What did Krause et al discover in 2002 about levels of IgE in 1987 and 1998 cohorts in Greenland?

A

Atopy roughly 20% in 1998 across all age groups

Ranged from 5-15 in each age cohort in 1987

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3
Q 
Hygiene Hypothesis 
If changes (in anything) occur across short time spaces, what does this suggest?
A

Must be environmental rather than genetic

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4
Q

Hygiene Hypothesis

What would geographical variation in genetically similar populations show?

A 
Likely to be due to environmental differences
// lifestyle western vs non
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5
Q

Hygiene Hypothesis

List some factors affecting atopy // allergy?

A 
Prenatal environment
- Maternal diet/smoking/pollution/stress
Birth
- Weight
- Mode of delivery 
Early Life
- Exposure to: allergens, moulds, pets, endotoxins, damp, plastics
- Infections
- Outdoor exposure - NO2, ozone
- Breast feeding
- Diet - oxidants, vitamin D, BMI
Adult Life
- Occupation
- Indoor exposure - ie domestic cleaning
- Diet - allergens/fats/antioxidants etc
- COCP
- Hormone changes
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6
Q

Hygiene Hypothesis
What did the 1958 British Cohort Study find with regards to older siblings?
What does this imply?

A

Increased older siblings = reduced prevalence of hayfever + eczema.

Implies having older siblings is associated with a protective factor for hayfever at 11,23/eczema
OR
Implies either that mothers who have atopic children don’t have any more children (selective fertility)
OR
Implies that as mothers have more children something INSIDE the mother changes

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7
Q

Hygiene Hypothesis
What did the 1958 British Birth Cohort find with regards to YOUNGER siblings? What does this imply regarding the selective fertility//maternal changes interpretations?

A

Decreased prevalence of hayfever at 11/23 and eczema as an infant with increased amounts of younger siblings

As both older + younger siblings are associated with decreased atopy maternal changes/selective fertility interpretations cannot be explanatory for the findings

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8
Q

Hygiene Hypothesis

What was 1958 british birth cohort?

A

Cohort of babies born in 1958 followed throughout life -> answer questionnaires

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9
Q

Hygiene Hypothesis
What did the 1958 british cohort show when correcting for father social class, housing tenure, shared household amenities and breast feeding?

A

Trend for decreased prevalence of atopy still existed

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10
Q

Hygiene Hypothesis

Systematic review for the association between family size (3+) and hayfever concludes what?

A

That 3+ in family is associated with dec hayfever

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11
Q

Hygiene Hypothesis
What do studies show with regards to “age of entry” at day-care/nursery in children from SMALL families <4 ppl @ home? Hay/skin/bronch
Kramer et al

A

Entering at 24+ months has 3.63x risk of developing hayfever if entering between 6-11months
Also 2.72x risk of positive skin-prick test
BUT trend to decrease 23% risk of getting bronchitis (NOT SIGNIFICANT)

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12
Q

Hygiene Hypothesis
What did Kramer et als cross sectional study show with regards to “age of entry” to daycare in children from large families? Hay/skin/bronc

A

Risks for each remained the same

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13
Q

Hygiene Hypothesis
What is the correlation between measles and atopy?
Guinea Bissau (had bad bout measles) (14-21yos)

But what could explain this?

A

With those who had measles there was a 64% reduction in atopy.
Could be explained though by “survival bias”
- Idea that atopic children more likely to die from measles
- Therefore appears “measles survivors” less atopic

  • The results of this study haven’t been replicated in other countries/less severe epidemics
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14
Q

Hygiene Hypothesis

What did the italian army recruits study depict with regards to siblings, and seropositivity to Hep A?

A

Prevalence of atopy decreased with increased older siblings IN SERONEGATIVE
Prevalence of atopy remained similar with increased older siblings in SEROPOSITIVE

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15
Q

Hygiene Hypothesis

What did Farooqui discover with regards to maternal atopy, pertussis and abx when <2?

A

Prevalence of hayfever, eczema and asthma increased with any one of these.
Having combinations/all further increases prevalence

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16
Q

Hygiene Hypothesis

What is a possible explanation for the positive association between ABx and allergic disease?

A

Asthmatics

  • More likely to suffer severe infections
  • More likely to go to doctor
  • Doctor more likely to give them ABx
  • Asthma may prevent with “infection” + be diagnosed subsequently
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17
Q

Hygiene Hypothesis
What correlations have been seen with Steiner schools and allergic disease?
What lifestyle differences are seen with steiner children?

A

Sig less atopy/asthma/hayfever

Greater prevalence:
- Breast feeding
- Measles
- Fermented veg consumption
- Organic foods
Red prevalence:
- ABx
- Paracetamol
- MMR vaccine
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18
Q

Hygiene Hypothesis
What did the ALEX study show with regards to rural farming vs rural non-farming, and un-pasteurised milk consumption/been inside stable <1yr old?

A

For each asthma, hayfever and IgE sensitisation prevalence is:
Stable and milk < Stable no milk < milk no stable < Milk or stable AFTER 1 yr < Never milk/stable

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19
Q

Hygiene Hypothesis

What did the systematic review show with regards living on a farm? Nasal symps, IgE sensitisation

A

Living on a farm (In UK belgium france NZ and sweden) does reduce atopy

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20
Q

Hygiene Hypothesis
What is the relationship between the range of microbes encountered and probability of asthma?
PARSFAL + GABRIELA studies?

A

The more diverse microbes encountered the smaller the probability of asthma

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21
Q

Hygiene Hypothesis

What did the ISAAC study show with regards to living on a farm and atopy though?

A

Protection from allergy/asthma is not present in ALL farming populations in ALL settings

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22
Q

Hygiene Hypothesis

What is the postulated hypothesis of BOWEL FLORA + allergy?

A

Gut flora crucial to immune development

  • May not occur with C section
  • May not occur with ABx
  • May be altered by probiotics
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23
Q

Hygiene Hypothesis

What did a study in Sweden and Estonia depict, with regards to lactobacilli in allergic infants?

A

Reduced lactobacilli in allergic infants

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24
Q

Hygiene Hypothesis
What was seen with regards to association of atopy, asthma, hayfever, atopic eczema and C section?
What is a possible confounder?

A

3.2x risk of asthma if C section
No associations with others

Asthmatic babies potientially at risk more in utero? -> more are delivered by c section?

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25
Hygiene Hypothesis What should the hygiene hypothesis be called? Why? What does evidence depict with regards to dampness and mould in the house?
The microbiome depletion or diversity hypothesis. - Early exposure to a range of "friendly" pathogens is necessary to train the immune system + develop a healthy microbiome - Increased hygiene will not impact chronic allergic conditions, but will increase infections ``` Evidence shows that there is sig increased: Wheeze Wheeze and atopy URI Asthma ``` Across ages 1-3 with none-high dampness/mould
26
Nutritional Epidemiology | What are the two broad methods of food quantification?
Intake in short term - Weighed records - Recall Frequency intake over longer period
27
Nutritional Epidemiology | What are the defining features of 24hr recall?
- Trained interviewer required - Recall bias - Reporting bias - Standardised protocol for interviewers - Substantial data handling - Must repeat to obtain average
28
Nutritional Epidemiology | What are the defining features of weighed records?
High levels motivation Diet may change to make weighing easier Substantial data handling
29
Nutritional Epidemiology | List the defining features of a food frequency questionnaire?
- List of foods in a chart. Random error related to recall Recall bias - gender, BMI, mothers etc...
30
Nutritional Epidemiology | What sort of diet should be advised for a COPD/Asthma patient?
DASH diet - Rich in fruit/veg/antioxidants Vit D Low salt/fats VitC/E/Flavinoids
31
Epidemiology Intro | List 3 trypes of error in studies
Random error | Systematic Error - Bias, Confounding
32
Epidemiology Intro | Want to find out the relationship between asthma and diet. Which is the outcome?
Asthma
33
Epidemiology Intro | What does PICO stand for?
Population Intervention/Indicator Comparator/Control Outcome
34
Epidemiology Intro For a patient with COPD, is taking a combination of simvastatin and ezetimide associated with a reduced incidence of CV events in comparison to placebo. PICO this mofo
Population - COPD Patients Intervention/indicator - Simvastatin/ezetimide Comparator - placebo (no simv ez) Outcome - CV events
35
Epidemiology Intro In older women with recurrent UTIs, does the use of prophylactic antibiotics reduce the recurrence rate. PICO this mofo
Population - Women with recurrent UTIs Indicator / vention - Prophylactic ABx Comparator - Placebo Outcome - recurrence rate of UTIs
36
Epidemiology Intro | Infants born prematurely, compared to those born at term, what is the subsequent lifetime prevalence of COPD?
Population - Infants (through life) Indication/intervention - Premature birth Comparator - Full term babies Outcome - COPD (overall prev)
37
Epidemiology Intro | What is causality?
When an exposure is proven to lead to an outcome.
38
Epidemiology Intro | What is the main difference between interventional and observational studies?
Intervention - exposure is assigned | Observational - Exposure is not assigned
39
Epidemiology Intro | What is the pyramid of study designs?
``` Systematic reviews/metanalysis RCTs Cohort Case control Cross sectional Case Series Anecdotal ```
40
Epidemiology Intro | What is the relationship between sample size and differences between individuals with RCTs?
As the sample size increases, substantial differences between each treatment arms will minimise. Idea is that the only difference should be the intervention
41
Epidemiology Intro | What are potential issues with RCTs?
``` Danger of selection bias Loss to follow up Blinding Problems Compliance with an intervention Was randomisation effective? ```
42
Epidemiology Intro | What is a cross sectional study?
Take a population-representative sample Then look at the number of people WITH the disease, exposure or condition. Then look at the people WITHOUT the disease, condition or exposure. Can calculate prevalence of disease, condition or exposure.
43
Epidemiology Intro | What is prevalence?
Number of cases in a defined population at one time point / number of people in a defined population at same time point
44
Epidemiology Intro | What is the prevalence ratio?
Prevalence of outcome of interest IN THOSE EXPOSED TO RF / prevalence in the UNEXPOSED
45
Epidemiology Intro | What is the odds ratio?
Ratio of: Odds of exposure to RF in those with outcome of interest / Those without the outcome Simpler With exposure and disease / with exposure without DIVIDED BY Without exposure WITH disease / without exposure without disease
46
Epidemiology Intro | Why are repeated cross sectional not the same as cohort studies?
Not the SAME cohort | Different groups of people over time
47
Epidemiology Intro | Although random samples are easy to do, due to modern technology, what is one problem of doing so?
Some people will not respond - removes complete randomisation Responder Bias
48
Epidemiology Intro | What are some forms of BIAS seen in cross sectional studies?
Response bias - in those who don't take part Recall bias possible Reporting bias Patterns of non-responses vary by disease BUT - women better than men - older tend to be better than young - Literate better than non - Disease itself may influence eh Stigmatised
49
Epidemiology Intro | List some facets of the ideal questonnaire?
``` Valid Reliable Easy to complete Data that is easy to analyse MUST COLLECT INFO ON - Outcomes - Exposures - Demographics - Confounders ```
50
Epidemiology Intro | What is a cohort study?
OUTCOME ABSENT AT BASELINE - Looks at exposed Vs non exposed - Identifies who develops disease Can be used to assess incidence
51
Epidemiology Intro | What must be pre-defined in cohort studies?
``` Hypothesis Groups studied Primary exposure + measurement Confounders and measurements Outcome and Measurements ```
52
Epidemiology Intro | What is the rate-ratio?
Rate in exposed / rate in unexposed
53
Epidemiology Intro | What is a case-control?
People with the disease -> look back in time to measure past exposures People without disease (controls) -> look back in time to measure past exposures
54
Epidemiology Intro | How do you work out the odds ratio in a case-control study?
Odds of exposure in cases / odds of exposure in controls
55
Epidemiology Intro | What does an odds ratio ACTUALLY show?
Measure of the Strength of an association between a risk factor and an outcome.
56
Epidemiology Intro | What is an ecological study?
Compare aggregate levels of exposures and outcomes at a group level - NO Individual data
57
Epidemiology Intro | What type of studies are best for rare diseases?
Ecological + case control
58
Epidemiology Intro | What study type is best for investigation of rare exposures?
Cohort
59
Epidemiology Intro | What study type is best for multiple exposures?
Case-Control > cohort
60
Epidemiology Intro | What study type is best for the measurement of time relationship between exposures + outcomes?
Cohort
61
Epidemiology Intro | Incidence, best study type?
Cohort -> forward in time
62
Epidemiology Intro | What are some routine sources of data for prevalence?
``` Mortality - ONS Health service utilisation - GP attendence - Prescriptions - Attendence at A+E - Hospital admissions THESE ARE ALL HOSPITAL EPISODE STATISTICS ```
63
Epidemiology Intro | Why are hospital episode statistics recorded?
Financial monitoring and performance Collected monthly Allows hospitals to be paid for the care they deliver Not designed for clinical use- used for research
64
Epidemiology Intro | What are some problems with hospital episode statistics?
Incompleteness Clinical coding inaccuracies Not everyone with diseases are admitted Some people admitted multiple times
65
Epidemiology Intro | Name two international initiatives for study of asthma?
ECRHS Europeans community respiratory health survey 20-44yos Postal questionnaire with subsample objective follow-up LF + BHR International study of asthma and allergy in childhood 6-7, 13-14yo children Parental questionnaire delivered through participating schools
66
Bias, Confounding, Chance, Causality | What is Bias?
A systematic error in the study that leads one to an incorrect conclusion
67
Bias, Confounding, Chance, Causality | What is selection bias?
Involving the people included or compared - Who is sampled - Loss to follow up - Self selection - Ascertainment bias
68
Bias, Confounding, Chance, Causality | What is information bias?
Bias in the measurements made - Misclassification - Measurement error - Recall - Interviewer bias - Differences in the way the exposure or outcome is measured
69
Bias, Confounding, Chance, Causality | Why is self-selection of controls bad?
Healthy worker effect
70
Bias, Confounding, Chance, Causality | Missing data can be extrapolated by imputation. Why is this still bad?
Will never know the true values
71
Bias, Confounding, Chance, Causality What is non-differential classification? What is differential?
When the same proportion of each group is subject to misclassification. When different proportions are subject to misclassification - WORSE
72
Bias, Confounding, Chance, Causality | What is reverse causality?
When the exposure is the result of the disease rather than the cause.
73
Bias, Confounding, Chance, Causality | What is observer bias?
When assessment of the exposure is influenced by awareness of the case/control status
74
Bias, Confounding, Chance, Causality | What is confounding?
When there is an alternative explanation for an observed association. CORRELATION DUNT EQUAL CAUSATION
75
Bias, Confounding, Chance, Causality | 3 rules of a confounder?
Must be associated with the exposure Must be an INDEPENDENT risk factor for the outcome Should not be on the causal pathway
76
Bias, Confounding, Chance, Causality | List ways, at the design stage, of minimising the effects of confounders?
Randomisation Restriction - (excluding people with confounding) Matching
77
Bias, Confounding, Chance, Causality | List ways, at the analysis stage, of minimising the effects of confounders?
Stratification Standardisation Statistical modelling
78
Bias, Confounding, Chance, Causality | What is multivariate modelling?
Examines whether an association exists between an exposure and outcome, taking confounding factors into account - A variate that adds significantly to the model may not be a confounder - Always best to adjust before the study
79
Bias, Confounding, Chance, Causality | What is residual confounding?
Confounding that remains despite adjusting. | - IE adjustment not rigorous enough: eg young vs old
80
Bias, Confounding, Chance, Causality What are the bradford-hill criteria? [9] (most important listed first [4])
Temporality - time dependent Strength - [of association ie high OR] Consistency - repetitive Biological Plausibility Dose-response Reversibility ie RCT needed Specificity - one cause/one effect Coherence - does not contradict common knowledge Analogy - Recognising similarities between exposures
81
Bias, Confounding, Chance, Causality | How can [random] sampling error be reduced?
Large sample size | Calculation of CIs

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