Nutrition research

Question 1

What are observational studies

Answer 1

Variables that are suspected of producing an effect are observed and the investigator measures but does nott intervene

Question 2

What are experimental studies

Answer 2

Hypothesis testing of causal relationships between independent and dependent variables where the investigator influences events

Question 3

What is epidemiology

Answer 3

The study of disease in populations

Question 4

Which type of study takes an epidemiological approach

Answer 4

Observational

Question 5

What types of studies are observation studies

Answer 5

Case control, cross sectional and cohort studies

Question 6

What are the benefits of observational studies

Answer 6

Build up evidence to support a suggested effect (diet on disease) which is useful for generating hypothesises

Question 7

What are confounding variables

Answer 7

Variables that can provide alternate explanations for an association in observational studies as they are associated with both the exposure (diet) and outcome (disease)

Question 8

How can confounding variables be dealt with

Answer 8

Matching or restricting participants, data analysis e.g. age standardisation or by adjustment of statistical models

Question 9

What are cross sectional studies

Answer 9

Observational study that provides a snapshot of epidemiological data on nutrition, identifying the nutritional needs of a population to inform health promotion and can estimate the prevalence of disease at a single time point

Question 10

What are the uses of cross sectional studies

Answer 10

Planning of services/ interventions, raising questions of association, investigating fixed exposures, national nutrition policies

Question 11

What are case control studies

Answer 11

Two groups cases (with disease) and controls (without disease) that have had exposure to dietary factor of interest are retrospectively compared to estimate associated of factor with risk of diseases

Question 12

What are the conditions of case control studies

Answer 12

Case population should be large enough and have a high enough incidence of disease to ensure enough cases over study course
Controls should be from the same population or one that represents the population that the cases were drawn from

Question 13

What are the strengths of case control studies

Answer 13

Quicker and cheaper than cohort studies
Cases and controls can be matched to reduce confounding

Question 14

What are the limitations of case control studies

Answer 14

Selection bias- low response rates, pre existing knowledge of topic, different selection of cases and controls
Measurement bias- retrospective (recall bias), misclassification

Question 15

What are cohort studies

Answer 15

Individuals are followed up over a period of time and disease and health outcomes are assessed

Question 16

What are the benefits of a cohort study

Answer 16

Can assess multiple outcomes and exposures at once
Allows measure of disease incidence as healthy population followed over time
Can calculate relative risk (RR)

Question 17

Can observational studies determine causation

Answer 17

No, only potential associations

Question 18

What type of study is this ‘comparison or previous olive oil consumption between cases of heart disease and healthy controls’

Answer 18

Case control

Question 19

What type of study is this ‘Start with a group of healthy individuals whose baseline diet (i.e., olive oil) would be recorded.
Participants would be followed up over several years to compare new cases of heart disease between those consuming different levels of olive oil’

Answer 19

Cohort

Question 20

What type of research does the researcher actively participates/conducts

Answer 20

Both observational and experimental

Question 21

What are experimental/intervention studies

Answer 21

Experimental studies which generate a hypothesis and demonstrate causation by altering consumption of a dietary pattern in a controlled way to measure the effect

Question 22

What are the three types of experimental studies

Answer 22

Randomised controlled trials (RCT), controlled trials and quasi experimental

Question 23

What are RCT

Answer 23

randomisation of participants by someone other than the investigators/clinicians/participants to generate comparable groups with respect to e.g. age, sex, weight to allow an effect to be measured

Question 24

What are the uses of RCT

Answer 24

Establish causal relationships
Asses effects of healthcare interventions, nutrition/diet on health
Determine benefits of nutrition/diets and efficiency of interventions
Compare doses/amounts of a particular nutrition/diets

Question 25

What are controlled trials

Answer 25

Non-randomised

Question 26

What are quasi experiments

Answer 26

Intervention is applied to a selected group of individuals, who are compared to a control group who have received no intervention

Question 27

What are the strengths of experimental studies

Answer 27

Minimised confounding variables Flexible experiments through manipulation Powerful stats analysis Infer causation

Question 28

What are the limitations of experimental studies

Answer 28

Randomisation can be difficult Challenging to exactly represent a specific population Experiments are unusual social situations Ethical considerations

Question 29

What type of experimental study is the gold standard for establishing causal relationships

Answer 29

Randomised controlled trials

Question 30

What are systematic reviews

Answer 30

Answers a defined research question by collecting and summarising all empirical evidence that fits a pre specified criteria

Question 31

What is a meta analysis

Answer 31

Use of statistical methods to summarise the combined results of these studies

Question 32

What types of studies are at the top of the hierarchy of scientific evidence pyramid

Answer 32

Systematic review and meta analysis (specifically of RCT)

Question 33

Why are systematic reviews and meta analysis at the top of the hierarchy of scientific evidence pyramid

Answer 33

Study design reduces bias and produces more reliable findings

Question 34

Describe the hierarchy of evidence pyramid from top to bottom

Answer 34

Systematic review and meta analysis RCT cohort studies Case control studies Cross sectional studies Case studies Mechanistic studies Editorials and expert opinion

Question 35

What are the function of descriptive studies (e.g. case studies)

Answer 35

To identify patterns of disease in terms of persons age, sec, place and time etc.

Question 36

What are descriptive studies

Answer 36

Describe specific characteristics of a population of interest e.g. case reports and series to discuss patient experiences of symptoms, treatment etc.

Question 37

What are the two types of analytical studies

Answer 37

Observational and experimental