Medical Studies

• You are head of a team of epidemiologists working at the QMC

• There have been claims in reports that teenagers aged 16 – 19 who eat chips OR chocolate at least 5 times a week are more likely to suffer from premature greying of hair (before the age of 25)

• It is your task to design a study that will either confirm or reject the claims in the reports.

• You have been assigned the staff and students of High Pavement college as your subjects.

• You have 10 years in which to complete your study.

• What will you do? How will you ensure that your results are fair, reliable and valid?

• Work with your co – epidemiologist to design the perfect study. You need to consider the costs involved

• You need to submit a report to the chief medical practitioner (Jemma) by the end of the lesson

Your plan should include…

• Who are you going to study?

• How often?

• How will you measure the grey hair?

• How will you control or take into account other factors that may cause premature grey hair?

• How will you keep track of people in your study?

Follow over time

compare exposure to risk factors

and draw conclusions

group with condition

group without condition

Follow over time

compare outcomes and

draw conclusions

group with condition

group without condition

Follow over time

group with condition

group without condition

Population exposed to risk factor

Population not exposed to risk factor

Population

OR

COHORT STUDIES - a group of people are followed over time to see who develops the disease.

Case Control – a group of people who have the disease are compared with a group who do not have the disease

cases without condition

cases with condition

Take histories of exposure to risk

factors, compare and draw conclusions

Features of a good study• Should include a clearly stated hypothesis or aim• A representative sample selected from the wider population that the

study’s conclusions will be applied to• The proportion of people who drop out should be kept to a minimum• Must produce valid data – the method used to collect the results

must be reliable • Any variables that could affect the measurements should be

controlled or taken into account• Conduct a survey on lifestyles• The disease diagnosis must be clearly defined to ensure that

different doctors record and measure the symptoms in the same way.

• Use a large sample• The effect of all variables that could affect the disease should be

considered