Epidemiology 2

Scientific Research Process, Prevalence & Incidence

What are the components of Evidence-Based Healthcare (EBHC)?

Patient choice, clinical experience, and best available evidence.

Why must we understand how evidence is produced?

To assess validity, reliability, sampling methods, data accuracy, and use of suitable statistical tests.

What is the Scientific Research Process used for?

Understanding and appraising published evidence.

What are descriptive study designs?

They describe without establishing exposure-outcome relationships e.g., case study, case report, series, cross-sectional.

What are analytic study designs?

They establish associations or causation between IV and DV. Include observational and experimental designs.

What are types of observational study designs?

Cross-sectional, ecological/correlational, cohort, case-control.

What are types of intervention/experimental study designs?

Randomised controlled trials (RCTs), non-randomised or quasi-experimental designs.

What does PICO stand for in experimental studies?

Population, Intervention, Control group, Outcome.

What does PECO stand for in observational studies?

Population, Exposure, Comparison group, Outcome.

Give an example of a PICO research question?

Does Magnesium supplement reduce leg cramps in older adults?

Give an example of a PECO research question?

Is lack of exercise associated with poor academic performance among high school students?

What is morbidity?

The frequency or burden of disease in a population.

What are common measures of disease frequency?

Prevalence, cumulative incidence, and incidence rate.

What is prevalence?

The number of existing (old + new) cases in a population at a point or period in time.

How is prevalence calculated?

Prevalence = (number of existing cases / total population) × 100.

What is cumulative incidence?

Number of new cases during a time period divided by disease-free population at the start.

How is cumulative incidence calculated?

Cumulative Incidence = (new cases / at-risk population at beginning) × 100.

What is incidence rate?

New cases during a time period divided by total disease-free person-time at risk.

What is person-time?

The total disease-free time each person contributes to the study (e.g., person-years, person-months).

How is incidence rate calculated?

Incidence Rate = (new cases / total person-time) × multiplier (e.g., 1000 person-months).

Give an example calculation of incidence rate?

IR = (2 / 174) × 1000 = 12 new cases per 1000 person-months.

Why is person-time useful?

It accounts for differing lengths of follow-up among participants.