Flashcards in Epidemiology and ACS - McFarland Deck (24):
Descriptive epidemiology describes what?
Distribution of disease
Analytic epidemiology describes what?
Determinants of disease
What topics are important in a critical review of the medical literature for a specific question or condition?
1. what is the question of the study
2. what is the study design
3. what is the exposure used
4. what are the outcomes and how are they measured
5. what are the inclusion and exclusion requirements
6. analysis of results
7. what are the biases and limitations of the study
8. what is the validity/generalizability of the study results
Which types of epidemiological studies are descriptive?
2. case studies
Which types of epidemiological studies are analytic?
1. Experimental - both clinical trials and community
2. Observational studies including cohort (both prospective and retrospective) and case-control studies
What is prevalence?
# of existing cases of a disease/ # in total population at a point in time
What is cumulative incidence?
# of new cases of a disease/ # in candidate population over a specified period of time
What is incidence rate?
# of new cases of a disease/ person during a time of observation in a candidate population
Incidence and prevalence are measures of what?
Absolute measures and relative measures are what?
Measures of comparison. Relative measures include prevalence ratio, risk ratio, rate ratio and odds ratio. Absolute measures include prevalence difference, risk difference and rate difference.
What are the guidelines for causality?
1. strength of association - strong associations are more likely to be causal
2. temporality - is there evidence that exposure preceded disease
3. biological gradient/dose response - does disease risk increase as exposure level increases
4. plausibility - does the association make sense
5. consistency - do different studies using different designs yield similar results
What is bias?
a systematic error that results in an incorrect or invalid estimate of the measure of association
Internal validity asks what question?
Are the results free of bias?
External validity asks what question?
Are the results generalizable?
Which is more important - internal or external validity?
How do you increase external validity?
1. use random sampling
2. use large sample sizes
3. high response rates
What is selection bias?
“is an error that results from procedures used to select subjects and from factors that influence participation in the study.”
Preferential or uneven selection of subjects
• Most likely to occur in retrospective studies because the exposure and outcome have occurred.
What is information/observation bias?
Recall- occurs when there is a different level of accuracy in the information provided by compared groups (i.e. cases vs. controls, exposed cohorts vs. unexposed cohorts)
Interviewer- a systematic difference in soliciting, recording or interpreting information that occurs in studies using in person or telephone interviews.
What is lead-time bias?
All cases are not detected at the same stage of the disease. (cancer)
What is the Hawthorne effect?
if a subject knows that he/she is being observed or being investigated, their behavior and response can change.
What is repeat-testing bias?
In a pre-test/post-test situation, the subjects tend to remember some of the previous questions and they do better regardless of the intervention. Or they may be fatigued and that alters their response.
A confounding variable must…..?
1. be associated (non-causally or causally) with the exposure
2. Associated (causally) with the outcome, independent of the exposure
3. NOT be an intermediate variable in the causal pathway
What are the ten leading causes of death in the US?
1. Heart Disease:
2. Malignant Neoplasms (Cancer)
3. Chronic Lower Respiratory Diseases
4. Stroke (Cerebrovascular diseases)
5. Unintentional Injury (Accidents)
6. Alzheimer’s Disease
7. Diabetes Mellitus
8. Influenza & Pneumonia
9. Nephritis and Nephrosis
10. Suicide (Intentional self-harm)