Nutritional Epidemiology

Question 1

Define nutritional epidemiology?

Answer 1

The study of how a disease or health outcome is distributed in populations and what factors determine this distribution

Question 2

What are the aims of nutritional epidemiology?

Answer 2

• describe distributions, patterns, extent of a disease in populations
• understand why disease is more common in some groups than others
• provide information necessary to plan, control and treat nutritional diseases

Question 3

What are the 3 steps of nutritional epidemiology research?

Answer 3

Assessment > Policy development > Assurance

repeat

Question 4

Nutritional epidemiology cannot establish factual cause of a disease, instead what can it do?

Answer 4

Suggest/provide evidence of associations

Question 5

What are some limitations of nutritional epidemiology?

Answer 5

• measurements can lack precision due to complexity of diet
• findings can be multifactorial
• Biochemical measures may not reflect actual nutrient intake

Question 6

What are the 2 types of nutritional epidemiological studies?

Answer 6

Experimental (investigator intervenes)

Observational (descriptive)

Question 7

What does a experimental nutritional epidemiology study involve?

Answer 7

• subjects are exposed to the nutrient to determine whether there is a difference in incidence of disease (can be done with supplements, drugs)
• investigator controls the exposure

Question 8

What does a observational nutritional epidemiology study involve? What are some examples of observational study designs?

Answer 8

• investigator has no control over nutrient exposure

- cross-sectional, cohort (retrospective & prospective)

Question 9

What is a cross-sectional study?

Advantages and limitations?

Answer 9

A study where subjects are measured at the same point in time

Strengths:
Inexpensive, quick, no drop-outs

Limitations:
Only a snapshot, bias

Question 10

What is a cohort study?

Advantages and limitations?

Answer 10

An observational study that follows a chosen population (cohort), identifying outcomes as they occur

Adv:

• produces best data (statistical power)
• longitudinal
• can examine a range of outcomes

Dis:

• expensive
• bias?
• time consuming

Question 11

What is an intervention study? (also known as experimental study OR clinical trails OR randomised control trials)
Advantages and limitations?

Answer 11

• a study where a variable is modified in one or more groups of subjects
• effects followed-up and recorded
• contains a control cohort
  e. g. supplementation/treatments

Adv:

• ‘Gold standard’ of studies
• control and treatment groups
• random allocation, reduces bias

Dis:

• expensive
• time consuming
• compliance
• difficult to recruit

Question 12

What is the difference between incidence and prevalence?

Answer 12

Incidence - number of new cases of the disease over a specific time period

Prevalence - total number of cases of the disease existing at any time

Question 13

How is relative risk (RR) determined?

Answer 13

A comparison of the incidence and prevalence of a disease

Question 14

What is the relative risk (RR) scale?

Answer 14

RR = 1 - no difference
RR = >1 - exposure is dangerous
RR = <1 exposure is protective

Question 15

What is a hazard ratio (HR)?

Answer 15

Refers to the probability of an event within a particular time.

E.g. Patients drinking fruit juices recover quicker from surgery compared to patients who don’t drink anything (HR=0.24)

Question 16

What is odds ratio (OR)?

Answer 16

A measure of probability.

*theoddsthat an outcome will occur given a particular exposure, compared to theoddsof the outcome occurring in the absence of that exposure.

Question 17

What does a meta-analysis do?

Answer 17

-combines all the findings from a set of independent studies to calculate an overall conclusion