A prospective cohort study investigates the association between regular consumption of a n… — USMLE Step 3

A prospective cohort study investigates the association between regular consumption of a novel processed food additive (Compound X) and the development of metabolic syndrome. The study follows a population of $100,000$ healthy adults for $5$ years. The cohort includes $37,500$ adults who regularly consume Compound X (exposed) and $62,500$ adults who do not consume it (unexposed). At the end of the $5$ -year follow-up, $1,875$ individuals in the exposed group and $625$ individuals in the unexposed group have developed metabolic syndrome. Based on these findings, what percentage of the total metabolic syndrome cases in this study population is attributable to the consumption of Compound X?

A
$25.0\%$
B
$40.0\%$
$60.0\%$ Cevap
D
$75.0\%$
E
$80.0\%$

Cevap

The correct answer is

60.0\%

The correct answer identifies the Population Attributable Risk Percent (PAR%), which measures the proportion of disease in the entire study population that is attributable to a specific exposure. It is calculated using the formula

PAR\% = \frac{I_p - I_u}{I_p}

, where

I_p

is the incidence in the total population and

I_u

is the incidence in the unexposed group. First, calculate the total population incidence:

I_p = \frac{1,875 + 625}{100,000} = 0.025

. Next, calculate the background incidence in the unexposed group:

I_u = \frac{625}{62,500} = 0.010

. The absolute excess risk in the population (PAR) is

0.025 - 0.010 = 0.015

. Dividing this by the total population incidence gives the PAR%:

\frac{0.015}{0.025} = 0.60

, or

60.0\%

Adım Adım Çözüm

Calculate the incidence rate of metabolic syndrome in the total study population (

I_p

I_p = \frac{1,875 + 625}{100,000} = \frac{2,500}{100,000} = 0.025

The total incidence is required as the baseline denominator to determine the fraction of disease in the entire population.

Calculate the incidence rate of metabolic syndrome in the unexposed group (

I_u

I_u = \frac{625}{62,500} = 0.010

The unexposed incidence represents the background risk of the disease that occurs independently of the exposure.

Calculate the Population Attributable Risk (PAR).

PAR = I_p - I_u = 0.025 - 0.010 = 0.015

PAR determines the absolute excess risk of disease in the overall population that is due to the exposure.

Calculate the Population Attributable Risk Percent (PAR%).

PAR\% = \frac{PAR}{I_p} = \frac{0.015}{0.025} = 0.60

60.0\%

PAR% defines the percentage of total cases in the population that could hypothetically be eliminated if the exposure were entirely removed.

Anahtar Kavram

Population Attributable Risk Percent (PAR%)

Soru

Cevap

Adım Adım Çözüm

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