Rapid Review: Epidemiology Flashcards
How do you interpret the following 95% confidence interval for a relative risk of .582: .502, .673
These data are consistent with relative risks range from .502 to .673 with 95% confidence (the true RR will be between .502 and .673 95/100 times)
Bias introduced into a study when a clincian is aware of the patient’s treatment type
Observational bias
Bias introduced when screening detects a disease earlier and thus lengthens the time from diagnosis to death
Lead-time bias
If you want to know if geographical location affects infant mortality rate but most variation in infant mortality is predicted by socioeconomic status, then socioeconomic status is a ___
Confounding variable
The proportion of people who have the disease and test + is the ___
Sensitivity=TP/(TP+FN)
Sensitive tests have few ___ and are used to rule ___ a disease
Negatives, out
PPD reactivity is used as a screening test because most people with TB will have a + PPD. Highly sensitive or specific?
Sensitive
Chronic diseases such as SLE–higher prevalence or incidence?
Higher prevalence
Epidemics such as influenza–higher prevalence or incidence
Higher incidence (but not really)
What is the difference between incidence and prevalence?
Prevalence is the percentage of cases of disease in a population at 1 snapshot in time. Incidence is the percentage of new cases of disease that develop over a given time period among the total population at risk.
Cross-sectional survey–incidence or prevalence?
Prevalence
Cohort study–incidence or prevalence?
Both
Case-control study–incidence or prevalence
Neither
Describe a test that consistently gives identical results, but the results are wrong
High reliability (precision), low validity (accuracy)
Difference between a cohort and case-control study
Cohort studies can be used to calculate RR, incidence, and/or odds ratio. Case control studies can be used to calculate an OR (estimate of RR when the disease prevalence is low).
Cohort studies compares those with a risk factor to those who do not have the risk factor. Case control studies compare people with a target disease to those who don’t have the target disease.
Attributable Risk?
The difference in risk in the exposed and unexposed groups
Relative Risk
Incidence in the exposed group divided by the incidence in the unexposed group
The results of a hypothetical study found an association between ASA intake and risk of heart disease. How do you interpret an RR of 1.5?
In patients who took ASA, the risk of heart disease was 1.5 times that of patients who did not take ASA.
Odds ratio?
In cohort studies, the odds of developing the disease in the exposed group divided by the odds of developing the disease in the nonexposed group.
In case control studies, the odds that the cases were exposed divided by the odds that the controls were exposed.
In cross sectional studies, the odds that the exposed group has the disease divided by the odds that the nonexposed group has the disease
The results of a hypothetical study found an association between ASA intake and risk of heart disease. How do you interpret an OR of 1.5?
In patients who took ASA, the odds of acquiring heart disease were 1.5 times those of patients who did not take ASA
In which patients do you initiate colorectal cancer screening early?
Patients with IBD, FAP, HNPCC, first degree relatives with adenmatous polyps or colorectal cancer
The most common cancer in men and the most common cause of death from cancer in men
Prostate cancer is the most common cancer in men, but lung cancer causes more deaths
The percentage of cases within 1 SD of the mean? 2 SDs? 3 SDs?
68%, 95.4%, 99.7%
Birth rate?
Number of live births per 1000 population in 1 year.
Mortality rate?
Number of deaths per 1000 population in 1 year.
Neonatal mortality rate?
Number of deaths from birth to 28 days per 1000 live births in 1 year
Infant mortality rate?
Number of deaths from birth to 1 year of age per 1000 live births in 1 year
Maternal mortality rate?
Number of deaths during pregnancy to 90 days pospartum per 1000,000 live births in 1 year
