Epidemiology Flashcards
Bias introduced when screening detects a dz earlier and thus lengthens the time from dx 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 SES, then SES is a ___.
Confounding variable
(#TP)/(#pts with the dz)
Sensitivity
Sensitive tests have few FN and are use to rule __ a dz.
Out
PPD reactivity is used as a screening test bc most ppl with TB (except those who are anergic) will have a (+) PPD. Highly sensitive or specific?
Highly sensitive for TB
Chronic dzs such as SLE: higher prevalence or incidence?
Higher prevalence
Epidemics such as influenza: higher prevalence or incidence?
Higher incidence
Cross-sectional survey: incidence or prevalence?
Prevalence
Cohort study: incidence or prevalence?
Incidence and prevalence
Case-control study: incidence or prevalence?
Neither
Describe a test that consistently gives identical results but the results are wrong.
High reliability, low validity
Difference between a cohort and case-control study
- Cohort studies: can be used to calculate relative risk (RR), incidence, and/or odds ratio (OR)
- Case-control studies: can be used to calculate an OR
Attributable risk
(Incidence rate (IR) of a dz in exposed) - (IR of a dz in unexposed)
Relative risk (RR)
(Incidence rate (IR) of a dz in a population exposed to a particular factor) / (IR in those not exposed)
Odds ratio (OR)
WRONG!!!!
Likelihood of a dz among individuals exposed to a RF compared to those who have not been exposed
Number needed to treat (NNT)
1 / (rate in untxed group - rate in txed group)
In which pts do you initiate CRC screening early?
- Have IBD
- Have FAP/HNPCC
- Have 1st-degree relatives with adenomatous polyps (less than 60 yo) or CRC
- MC CA in M
2. MCC of death from CA in M
- Prostate CA (MC CA in M)
2. Lung CA (MCC CA deaths in M)
The % of cases within 1 SD of the mean? 2 SDs? 3 SDs?
68%
- 4%
- 7%
Birth rate
live births (LBs) per 1000 population in 1 yr
Fertility rate
LBs per 1000 females (15-44 yo) in 1 yr
Mortality rate
deaths per 1000 population in 1 yr
Neonatal mortality rate
deaths from birth - 28 days per 1000 LBs in 1 yr
Postnatal mortality rate
deaths from 28 days - 1 yr per 1000 LBs in 1 yr
Infant mortality rate
deaths from birth - 1 yr per 1000 LBs in 1 yr (neonatal + postnatal mortality)
Fetal mortality rate
deaths from 20 wks gestation - birth per 1000 total births in 1 yr
Perinatal mortality rate
deaths from 20 wks gestation - 1 mo per 1000 total births in 1 yr
Maternal mortality rate
deaths during pregnancy - 90 days PP per 100,000 LBs in 1 yr
Bias introduced into a study when a clinician is aware of the pt’s tx type
Observational bias
