Health Promotion, Prevention, and Public Health
This domain tests prevention, screening, and population-level reasoning, including how prevalence changes the meaning of a test result.
Screening logic
A screening programme is justified when the condition is important, has an accepted treatment, has a detectable latent stage, and the test is acceptable and affordable. Screening differs from diagnosis: a positive screen requires confirmatory assessment.
Prevention in practice
- Advise smoking cessation; it reduces risk across cataract, age-related macular degeneration, and vascular disease.
- Recommend UV protection and eye safety eyewear for occupational and sports risk.
- For intermediate age-related macular degeneration, the AREDS2 formulation is the evidence-based supplement; it is not for early disease or for prevention in unaffected patients.
- Ask about falls, driving, and diabetes control, because these connect ocular findings to function and systemic risk.
- Amblyopia screening in young children relies on acuity or photoscreening so treatment starts during the sensitive period.
Worked example
A screening test has 90 percent sensitivity and 90 percent specificity, and prevalence is 1 percent in 10,000 people. Reasoning: 100 have disease, so 90 are true positives; 9,900 are healthy, so 990 are false positives. Positive predictive value is 90 divided by 1,080, about 8 percent. Most positives are false, so confirmatory testing is essential.
Traps that cost marks
Confusing sensitivity with positive predictive value; ignoring prevalence; treating a screening result as a diagnosis; recommending supplements without the correct disease stage.