Cohort Studies

Question 1

what were the red spot babies

Answer 1

all babies born in may and june 1947 in Newcastle
1142
over first year of life info on hospital visits, health, housing
result: 14% houses unfit for habitation
1625 infections
children followed up annually to 15
90s hypothesis about birth weight and adult CVD
60+ year follow up - wealth of data

Question 2

what is a cohort

Answer 2

group of people who share a ‘common experience’

Question 3

what is a cohort study

Answer 3

follows a cohort over a period of time to see how their exposures affect their outcomes

Question 4

why may a cohort be chosen

Answer 4

they represent the general population, special exposure groups, special resource groups or geographically/facility defined groups

Question 5

what is the design of a cohort study

Answer 5

identify the cohort, assess exposure, assess outcome and interpret findings

Question 6

what is the Framingham heart study

Answer 6

1948
study impact of factors on CVD
cohort - defined population 30-62yrs live in Framingham did not have CHD
exposures = BP, weight, diabetes, smoking exercise
outcomes = CHD, stroke, congestive heart failure
evaluated every 2 years

Question 7

what questions are asked when looking at a cohort study?

Answer 7

does exposure to the risk factor affect chances of developing disease?
so is there more disease in unexposed group or exposed group

Question 8

what were the milestone findings of the Framingham studies?

Answer 8

1960 - smoking increases risk of heart disease
1961 - cholesterol and Bp increase risk of heart disease
1965 - first report on risk factors for stroke
1974 - diabetes associated with heart disease

Question 9

what is the UK biobank

Answer 9

cohort study of 500,000 middle aged adults in general population. UK
collect medical lifestyle data and samples
follow cohort participants over time for wide range of diseases
questionnaires
still going

Question 10

outline the issues with measuring the disease/other outcomes

Answer 10

must be done in the same way for exposed and unexposed groups to avoid INFORMATION BIAS
those assessing outcomes should be blinded to exposure status of the participant - to avoid observer bias

Question 11

what should be calculated in cohort study to find out if exposure affects chances of getting disease

Answer 11

relative risk and incidence rate
incidence rate separate for exposed and unexposed groups

Question 12

what are the strengths of cohort studies

Answer 12

clear temporal relationship between exposure and disease
eliminates possibility of recall bias
suitable for studying rare exposures
can study multiple outcomes from single exposure
can study complex interactions between exposures

Question 13

what can a good cohort provide

Answer 13

answers to questions the original investigators never thought of asking

Question 14

what are some potential challenges of cohort studies

Answer 14

defining and measuring exposure
defining and measuring disease
loss to follow up over long period
for diseases of long latency , may have to wait many years before first study result
non participation (selection) bias may affect external validity (generalisability) of results
very expensive
time consuming
logistically challenging

Question 15

what can cohort studies help establish

Answer 15

temporality