Health, Medicine, and Social Epidemiology (9A) - MCAT Psychological and Social Foundations

Secondary prevention. Detects disease early when treatment is most effective.

Exposure associated with increased probability of a health outcome. Statistical association, not necessarily causal.

Deaths in a population during a specified time period. Death rate per population unit over time.

Characteristic associated with increased probability of disease. Exposure that raises disease risk above baseline.

Probability test is positive given disease is present. True positive rate; ability to detect disease.

Epidemic = regional outbreak; pandemic = worldwide spread. Geographic scope distinguishes these outbreak classifications.

A characteristic associated with increased disease probability. Identifies factors that increase disease risk but may not cause it.

Correlation is association; causation means one variable produces change. Causation requires direct effect, not just statistical relationship.

Experimental study with random assignment to intervention vs control. Randomization minimizes confounding bias.

Deaths in a population per unit time. Usually expressed per 1,000 or 100,000 population.

Study of disease distribution and determinants in populations. Focuses on patterns and causes at the population level.

Number of new cases in a population over a time period. Measures disease onset rate, not existing cases.

Prevalence. Longer disease duration increases existing cases.

$\text{prevalence}=\frac{\text{existing cases}}{\text{population}}$. Proportion of population with disease at one time point.

$\text{risk}=\frac{\text{new cases}}{\text{population at risk}}$. Cumulative incidence measures probability over time.

Illness or disease burden in a population. Encompasses all non-fatal health conditions.

Exposure associated with increased probability of disease. Can be modifiable (smoking) or non-modifiable (age).

A third variable distorts the exposure–outcome association. Must be associated with both exposure and outcome.

Systematic differences from nonrandom participant selection. Occurs when study sample differs from target population.

Differential accuracy of remembered past exposures. Common when cases remember exposures better than controls.

Groups are defined by exposure and followed for outcomes. Prospective design: exposure precedes outcome.

Groups are defined by outcome; prior exposures are compared. Retrospective design: outcome already occurred.

Case-control. Starts with cases, making rare outcomes feasible to study.

$RR=\frac{\text{risk in exposed}}{\text{risk in unexposed}}$. Compares disease risk between exposed and unexposed.

$OR=\frac{\text{odds in exposed}}{\text{odds in unexposed}}$. Approximates RR when disease is rare.

No association (neither increased nor decreased risk). RR=1 means equal risk in both groups.

Systematic health differences linked to social disadvantage. Often tied to socioeconomic status, race, or geography.

Third variable related to both that distorts the true association. Must be associated with both exposure and outcome.

Study of disease distribution and determinants in populations. Focuses on patterns and causes at the population level, not individuals.