Introduction

Question 1

what is epidemiology?

Answer 1

study of patterns causes and effects of health and disease in defined populations
it informs our public health, policy, evidence-based practice - identifying risk factors and interventions for prevention

Question 2

why is epidemiology important?

Answer 2

understanding risks, used for designing public health interventions, underpins much of evidence-based medicine

Question 3

outline cholera

Answer 3

John snow
higher death rates in 2 areas supplied by same water company
identified pump on Broad street as cause of epidemic
used chlorine to clean handle and ended the outbreak

Question 4

outline the smoking ‘british doctors study’

Answer 4

prospective cohort study by medical research council
1951- wrote to UK physicians
40,000 responded, males
statistical evidence linking smoking to lung cancer

Question 5

outline AIDS epidemic 1980s

Answer 5

cohort study 1993 Schechter
followed 715 gay men for 8.6 years
all 126 AIDS cases only occurred in those 365 individuals with pre-existing HIV-1 antibody and CD4 counts fell - changed beliefs on aetiology
HIV-1 is involved in AIDS pathogenesis

Question 6

outline the Northern Region Young Persons Malignant Disease Registry

Answer 6

cancer registry
all cases of cancer diagnosed in those 0-24 years from 1968-today
population based - cases from defined geographical region and time

Question 7

what has the northern region young persons maligant disease registry shown

Answer 7

improved survival for children and young people with cancer
seasonal variation - indicates a role for environmental factors in aetiology
socio-economic disparities in survival

Question 8

how can we measure disease frequency

Answer 8

incidence rate
prevalence rate
mortality rate
relative risk
rate ratio
standardised morbidity ratio
odds ratio

Question 9

what are the 4 main study designs

Answer 9

case-control studies
cohort studies
cross-sectional studies
ecological studies

Question 10

what is the definition of bias

Answer 10

any systematic error in epidemiological study resulting in incorrect estimate of association between exposure and risk of disease
selection bias/misclassification bias

Question 11

what is the definiton of confounding

Answer 11

function of the complex interrelationships between various exposures and disease

Question 12

what is genetic epidemiology

Answer 12

study of role of genetic factors in determining health and disease in families and populations
gene-environment interactions

Question 13

what are the types of genetic study design

Answer 13

familial aggregation studies
segregation studies
linkage studies
association studies

Question 14

what are family aggregation studies

Answer 14

find out if there is a genetic component and what the relative contributions of the genes and environment are

Question 15

what are segregation studies in genetic epidemiology

Answer 15

find out the pattern of inheritance of disease (dominant or recessive)

Question 16

what are linkage studies in genetic epidemiology

Answer 16

find out which part of the chromosome the disease gene is located

Question 17

what are association studies within genetic epidemiology

Answer 17

find out which allele of which gene is associated with the disease

Question 18

what is the recent thing in genetic epidemiology

Answer 18

genome-wide association studies - lead to the discovery of many genetic polymorphisms that influence risk of developing common diseases

Question 19

what is life course epidemiology

Answer 19

study of antecedant exposures and later health outcomes
take into account pathways between the two and evolution of health disorders over time
used to study long term effects on chronic disease and risk of exposure during gestation, childhood, adolescence and later life

Question 20

what is perinatal epidemiology

Answer 20

period immediately before or after birth
congenital anomalies in children - aetiology and survival
reproductive loss

Question 21

what is the prevalence of cancer

Answer 21

approx 1 in 2 people will be diagnosed with cancer at some point in their lives
risk increases in people 50+

Question 22

what diseases does obesity increase the likelihood of

Answer 22

BMI > 30
heart disease
type 2 diabetes
obstructive sleep apnea
certain cancers
osteoarthiritis

Question 23

outline the Newcastle 85+ study

Answer 23

out of those ages 85+ years no one was disease free and on average each person has 4-5 conditions

Question 24

what are the methods used to investigate infections

Answer 24

outbreak investigation
disease surveillance
case-control studies
cohort studies
molecular epidemiology
vaccine assessments

Question 25

what is the definition of health inequality

Answer 25

differences in health status or distribution of health determinants between different populations

Question 26

what did the study of melanoma by McNally 2014 show

Answer 26

incidence and survival in young people in northern england found increased risk of melanoma was linked to greater affluence but worse survival associated with living in a more deprived area

Question 27

what is incidence rate used to measure

Answer 27

measure and compare disease frequency in populations good because rates adjust for population size

Question 28

what is the definition of incidence rate

Answer 28

number of new cases of a specified disease per population at risk in a given time period

Question 29

how is incidence rate calculated

Answer 29

(new cases occuring in given time period) / (population at risk during same time period)

Question 30

what should the numerator of the incidence rate equation not include

Answer 30

cases occurred/diagnosed earlier or later than the given time period

Question 31

what does the denominator of the incidence rate equation represent

Answer 31

the population from which the cases in the numerator arose from

Question 32

what is incidence rate specific for

Answer 32

age and sex females and males are calculated separately age calculated by 5 year group

Question 33

what must be ensured when calculating age/sex specific incidence

Answer 33

complete ascertainment of cases for a prescribed geographical area e.g country, county, district, ward

Question 34

what is the crude incidence rate

Answer 34

calculated as total number of cases / total population in the period

Question 35

what does the crude incidence rate not take into account?

Answer 35

the age structure of the population and cannot be used for comparison with other populations/countries

Question 36

what is an example of when crude incidence rate did not work

Answer 36

2 australian health surveys examined circulatory system health problems in general population and indigenous population in each age group over 24 years, indigenous had higher rates but crude incidence showed general as higher because the median age of indigenous was 21 and median age of general was 37

Question 37

how do we overcome the problem of comparing populations with different age structures?

Answer 37

weighting rates are weighted to a standard population e.g WHO AGE-STANDARDISED INCIDENCE RATE

Question 38

so how is age standardised incidence rate calculated

Answer 38

summary of individual age-specific rates using external population standard d(i) / y (i) = age specific rate for i category

Question 39

what is prevalence

Answer 39

frequency of existing cases how much of a particular disease is present in a defined population

Question 40

so what is the difference between the numerators of incidence and prevalence

Answer 40

indice numerator is new cases in given time period prevalence numerator is all cases present during given time period irrespective of when disease started both new and old cases

Question 41

what is the equation for prevalence rate

Answer 41

(persons with given disease/condition during specified time period) / (population during same time period)

Question 42

what is mortality rate

Answer 42

probability/risk of dying in population over a period of time frequency with which new death occurs in population over period of time

Question 43

what are some other types of mortality rate

Answer 43

perinatal mortality rate - neonatal death and stillbirth maternal mortality rate - 15-44yrs infant mortality rate -<1yr child mortality rate <5 yrs

Question 44

what is relative risk

Answer 44

measure of disease frequency by calculating ratios - risk ratio and rate ratio measures the strength of an association

Question 45

what is the risk ratio equation

Answer 45

risk (cumulative incidence) in exposed group / risk in unexposed group

Question 46

what is rate ratio equation

Answer 46

incidence rate in exposed group / incidence rate in unexposed group

Question 47

what is the odds ratio

Answer 47

odds of disease in exposed group / odds of disease in unexposed group

Question 48

what does the rate ratio do

Answer 48

compares 2 groups in terms or incidence/mortality rate the two groups differ by demographic or exposure rate ratio = rate for group of interest / rate for comparison group

Question 49

what does a rate ratio of 1 mean

Answer 49

identical risk in the 2 groups

Question 50

what does a rate ratio of > 1 mean

Answer 50

increased risk for numerator group

Question 51

what does a rate ratio of < 1 mean

Answer 51

increased risk for denominator group

Question 52

what is the odds ratio definition

Answer 52

estimate of risk from case-control studies measure of association - quantifies relationship between exposure and health outcome from comparative study (case-control study)

Question 53

what is the equation for odds ratio - case control studies

Answer 53

odd ratio = (a x d) / (b x c)

Question 54

what is the abcd of the odds ratio equation

Answer 54

a = ppl with disease and exposure of interest b = ppl without disease but with exposure of interest c = ppl with disease but without exposure of interest d = ppl without disease or exposure of interest

Question 55

and is a+c and what is B+D

Answer 55

ac = cases bd = controls

Question 56

what is the standard mortality ratio equation

Answer 56

SMR = observed cases / expected cases x 100

Question 57

outline standard morbidity ratio

Answer 57

can be morbidity mortality or incidence quantifies increase or decrease in those relative to general population

Question 58

what is the p value

Answer 58

measure of statistical significance probability of an event occurring due to chance alone higher p value = higher probability the event can be explained by chance from 0.0 to 1.0 cut offs 0.05/0.01