Observational Study Designs

Non experimental
1. effective for investigating causal links between exposures and disease
2. more susceptible to bias and confounding compared to randomised control trials.
3. 'non-intervention' studies that are conducted as people go about their daily life.
Types
1. Analytical
  1. cohort studies, case-control, or analytical surveys
    1. cross-sectional surveys
  2. examine relationships between variables (e.g. 'Does alcohol consumption increase the risk of breast cancer?').
2. Descriptive
  1. case reports, case series and simple surveys
  2. more commonly used to measure the incidence and prevalence of risk factors or disease
ANALYTICAL
1. Cohort Studies
  1. longitudinal in design, start with a selected group of disease-free people who are classified according to specific exposure (e.g. high/low alcohol consumption
  2. study group is followed over time to see who develops the disease/outcome (e.g. breast cancer).
  3. used to measure incidence (new cases of disease) and thus risk.
  4. Analyse results
    1. relative risk (RR)
    2. odds ratios (OR).
    3. represent the increased (or decreased) risk of disease for those in the exposed group
  5. Examples of questions
    1. 3.Does smoking increase the risk of lung cancer and other diseases?
    2. 4.Does breast-feeding play a role in breast cancer?
    3. 1.Does physical activity reduce the risk of heart disease?
    4. 2.Do high levels of HDL cholesterol reduce the risk of coronary death?

Resource summary

	Created by shirley.ha about 11 years ago