week 2 Flashcards
differentiate between passive and active disease surveillance
Passive: by healthcare providers, prone to underreported eg hospital records, primary care/family doctor records, patient or family member interviews
Active: by specific project staff by visiting healthcare facilities, performing interviews, reviewing medical records
t/f we can achieve complete information if we have sufficient resources and a restricted sample
no
how can data be misinformed in early stages
patient interviews (might choose not to go to doctor), records from primary care would be useful but handwritten
define rates
freq of an event in relation to a uni of time (denominator) eg # of deaths per year
define proportions
what fraction of the population has the disease eg #of positive COVID tests per 1000
define incidence and the formula
of new cases/total pop at risk
measure of risk for new events (new cases of disease)
of new cases/total pop at risk
define cumulative incidence and the formula
freq of new cases occurring during a defined time period – risk of developing the disease within this time period
(# of new cases/total pop at risk) x n
n being “incidence per n”
during cumulative incidence, the population must e relatively (open or closed )
closed
define person time
the total number of time all the individuals spent in the study (py (person years))
what is the relationship between prevalence and incidence
Prevalence = incidence x duration of disease
morbidity is related to which two components
Incidence and prevalence
incidence per 1000 is 4 cases/year and duration of disease is 3 years thus point prevalence per 1000 is ?
12 cases
define prevalence and what is the formula for prevalence per 1000
all the people with the disease, regardless of when they developed
(# of cases in time period/pop size at that time) x 1000
distinguish between point and period prevalence
Point prevalence: how many people have a disease at a certain time (likely usage of prevalence)
Period prevalence: how many people have had the disease at any point during a certain time period
is lower prevalence good for the population? why or why not?
may not be, death lowers prevalence
in some cases, higher prevalence may not be bad. why?
Higher prevalence may occur if new treatment lessens the severity (good)
state the condition for mortality to be a substitute for incidence
If low time between inception and death, mortality can be used as a substitute for incidence
what is the formula for mortality rate for all causes and for proportionate mortality (%)
(total deaths from all causes in 1 y/pop size at the midpoint of the year) x 1000
(# of deaths from spec cause in time/all deaths during that time) x 100
for the following conditions, state how the formula for mortality is changed
1. if you want specific cause of death
2. if you want specific segments of time
- If specific cause of death, then only numerator restricted
- If interested in specific segments then restriction to numerator and denominator
define case fatality and the formula
Measures the severity or fatality of the disease, mortality is the total pop
of indiv dying during spec time after DO or DD/# of indiv w specified diseases
DO = disease onset
DD = disease diagnosis
examine the following: “The incidence rate of a disease is 5x greater in women than in men but the prevalence rates show no sex difference.” what is the best explanation for the following
more women could be dying earlier that is why prevalence is low or if the recovery rate is higher in women then it would also explain why there is no diff
define years of potential life lost and formula
measure of premature mortality and preventable death
standard age - age at death
**then you add them all up for everyone who died from the same cause
explain what is a direct age adjustment
Direct age adjustment: pretend that both populations follow a standard age distribution, and then apply age specific mortality rates from both populations
