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Preventive Medicine Flashcards

7 cards from real SPEX practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. A new diagnostic test for diabetes has a sensitivity of 90% and specificity of 85%. In a population with 10% prevalence, what is the positive predictive value (PPV)?

    Answer: Approximately 40%

    Using Bayes' theorem: PPV = (0.90×0.10)/[(0.90×0.10)+(0.15×0.90)] = 0.09/0.225 ≈ 40%.

  2. Which occupational lung disease is caused by inhalation of free crystalline silica and is associated with increased risk of tuberculosis?

    Answer: Silicosis

    Silicosis from silica dust exposure impairs pulmonary macrophage function, substantially increasing susceptibility to tuberculosis.

  3. The 'healthy worker effect' in occupational epidemiology refers to:

    Answer: Employed populations appear healthier than the general population because severely ill individuals are less likely to work

    The healthy worker effect biases occupational studies toward lower observed mortality because the employed tend to be healthier than the general population.

  4. Which clinical preventive service is recommended by the USPSTF with a Grade B recommendation for all adults aged 35–70 who are overweight or obese?

    Answer: Screening for prediabetes and type 2 diabetes

    USPSTF gives a Grade B recommendation for prediabetes/type 2 diabetes screening in overweight or obese adults aged 35–70.

  5. In communicable disease control, 'herd immunity threshold' is calculated as 1 − (1/R₀). For measles with an R₀ of 15, what percentage of the population must be immune?

    Answer: 93%

    1 − (1/15) = 1 − 0.067 ≈ 0.933, meaning approximately 93% of the population must be immune.

  6. A chemical plant worker develops peripheral neuropathy after chronic low-level exposure to n-hexane. The primary toxic metabolite responsible is:

    Answer: 2,5-hexanedione

    n-Hexane is metabolized to 2,5-hexanedione, which crosslinks neurofilament proteins causing the characteristic 'giant axon' neuropathy.

  7. When evaluating a screening program, which statistical measure indicates the number of people who need to be screened to prevent one adverse outcome?

    Answer: Number needed to screen (NNS)

    Number needed to screen (NNS) is the reciprocal of the absolute risk reduction achieved by the screening program.