Exposure in Epidemiology Class 1

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Questions and Answers

What is serum 25(OH)D a biomarker of?

Vitamin D exposure (correct)

Disease prevalence

Health outcomes

Genetic mutations

Why is it important to consider the exposure-disease pathway?

To understand the causal events or states leading to disease (correct)

To focus solely on public health perspectives

To ignore the basic science perspective

To measure exposure at a single step

What happens as you move down the exposure-disease pathway?

What you measure is closer to the causal agent (correct)

The perspective shifts from basic science to public health

The study goal changes from public health to basic science

What you measure is further removed from the causal agent

What type of exposure is easy to define in terms of dose?

Binary exposures Signup and view all the answers

Is exposure to secondary smoke a binary exposure?

Sometimes Signup and view all the answers

What shifts as you move along the exposure-disease pathway?

The perspective of the study Signup and view all the answers

What is a challenge when trying to define exposure?

It can be culturally specific Signup and view all the answers

Why is it necessary to choose a surrogate measure of exposure?

Because true exposure is often not measurable Signup and view all the answers

When choosing a surrogate measure, what should be balanced?

Sensitivity and specificity Signup and view all the answers

What is an example of exposure occurring through multiple sources?

Caffeine intake through coffee and other sources Signup and view all the answers

What is the first step in measuring exposure?

Acknowledge that true exposure is often not measurable Signup and view all the answers

What is the purpose of isolating the biological agent of interest?

To make the measurement of exposure more specific Signup and view all the answers

Why is it important to specify the active agent when measuring exposure?

To make the measurement of exposure more specific and sensitive Signup and view all the answers

What is an example of a specific biological agent of interest?

Mercury in vaccines Signup and view all the answers

What is a common source of human exposure to mercury?

Eating fish and shellfish Signup and view all the answers

What type of chemicals are formed during the digestion of processed meat?

Nitrates and nitrites Signup and view all the answers

What is the biological agent of interest in the context of mercury exposure?

Methylmercury Signup and view all the answers

What is a key consideration when selecting an exposure measurement?

How the exposure relates causally to the outcome of interest Signup and view all the answers

What type of cancer is associated with the consumption of red meat?

Colon cancer Signup and view all the answers

What is a surrogate measure of exposure in the context of smoking?

The number of cigarettes smoked Signup and view all the answers

What is the exposure-disease pathway in the context of mercury exposure?

Mercury is released into the environment, causing health problems in utero and early in life Signup and view all the answers

What is the critical exposure window, and how does it relate to exposure measurement error?

The critical exposure window is the time period during which the exposure has the greatest causal effect on the outcomes. Including exposures outside of this window results in exposure measurement error. Signup and view all the answers

Why is it essential to consider the timing of exposure in epidemiological studies?

Considering the timing of exposure is essential because not all exposures matter, only those that occur during the critical or etiological window. Signup and view all the answers

What is an example of how the timing of exposure affects the outcome in prenatal development?

The effect of exposures during different trimesters of pregnancy on the outcome, such as birth defects or developmental abnormalities. Signup and view all the answers

How can the exposure timing affect the outcome in the context of cannabis use and schizophrenia-like deficits?

Exposure to cannabis during the peripubertal period is a risk factor for the emergence of schizophrenia-like deficits. Signup and view all the answers

What is the importance of considering the timing of exposure in relation to menopause in cardiovascular disease research?

Considering the timing of exposure in relation to menopause is important because postmenopausal women have a higher risk for cardiovascular disease, and not all women start menopause at the same age. Signup and view all the answers

Why is it essential to define the exposure accurately in epidemiological studies?

Defining the exposure accurately is essential to avoid measurement error and ensure that the exposure is being measured during the critical or etiological window. Signup and view all the answers

What is the implication of including exposures outside of the etiological window on exposure measurement?

Including exposures outside of the etiological window results in exposure measurement error. Signup and view all the answers

Why is it necessary to consider the timing of exposure in case-control studies?

Considering the timing of exposure is necessary in case-control studies to ensure that the exposure is being measured during the critical or etiological window, and to avoid measurement error. Signup and view all the answers

What is the importance of considering the time since last exposure in determining disease risk, especially for causes that occur late in the sequential cause chain?

It is important because those who were recently exposed will be at greatest risk, as seen in the example where current smokers have a threefold risk of myocardial infarction. Signup and view all the answers

What is regency analysis, and when is it used?

Regency analysis considers only recent exposure and is used for exposures that are causal in the later part of the sequential cause chain. Signup and view all the answers

How can the timing of exposure be related to disease risk using statistical approaches?

Statistical approaches can be used to relate the timing of exposure to disease risk by examining cumulative exposure dose for different non-overlapping time periods, multiple overlapping periods in separate models, or using weighted cumulative exposure with different weights for each time window. Signup and view all the answers

What should be considered when measuring exposure to ensure accurate results?

When measuring exposure, it is essential to consider the research question, biological agent of interest, where in the exposure-disease pathway to measure exposure, and the ideal and most feasible method of measurement. Signup and view all the answers

Why is it essential to specify the timing of exposure in measuring exposure?

Specifying the timing of exposure is crucial because it can affect the accuracy of the measurement and the subsequent association with disease risk. Signup and view all the answers

What should be considered when selecting an exposure measurement method?

When selecting an exposure measurement method, it is essential to consider the duration and frequency of exposure, as well as the timing of exposure. Signup and view all the answers

Why is it necessary to adjust for other exposure windows when examining the association between exposure and disease risk?

It is necessary to adjust for other exposure windows because components of dose and time are correlated, and exploratory modeling tends to overestimate the effect size. Signup and view all the answers

What are the three key steps in measuring exposure?

The three key steps in measuring exposure are identifying what to measure, identifying how and when to measure, and identifying what, how, and when to measure. Signup and view all the answers

Why is it important to exclude exposures that occurred in the induction or latent period when computing cumulative dose in a case-control study?

To avoid reverse causality and ensure that the exposure is truly related to the disease outcome. Signup and view all the answers

What is the purpose of latency analysis or exposure lagging in relating timing of exposure to disease risk?

To exclude exposures that occurred in the induction or latent period and focus on the etiological window. Signup and view all the answers

What type of exposure measurements are considered reliable in case-control studies?

Fixed exposures over time, such as genetic information. Signup and view all the answers

Why is it important to establish a reference date in case-control studies when assessing behavioral exposures?

To ensure that exposures are only included before any symptoms occur, avoiding reverse causality. Signup and view all the answers

What is the purpose of exposure window analysis in relating timing of exposure to disease risk?

To only count exposures that occurred in the etiological window, excluding exposures before and after. Signup and view all the answers

Why is time since first exposure or age at first exposure important in some causes?

Because these causes are early on the sequential cause chain, and timing of exposure is critical. Signup and view all the answers

What is a challenge when trying to relate timing of exposure to disease risk?

The timing of the etiological window, induction period, and latent period are often not known. Signup and view all the answers

Why is it important to consider the timing of exposure in case-control studies?

To avoid reverse causality and ensure that the exposure is truly related to the disease outcome. Signup and view all the answers

Study Notes