measuring ideas frequency Flashcards
-Health status can be measured using — and— measures and is usually observed by — or measured using —
- types of health n disease measurements includes:
- pathological ad clinical
- observed by clinicians
- instruments
1-Signs e.g. blood pressure, heart rate, temperature, body weight
2-Symptoms e.g. disease specific checklists
3-Medical testing e.g. blood tests, radiography, spirometry
criteria for measuring health:
1- —- criteria if the measure is intended for routine use as part of clinical practice. this must be appropriate n relevant and the measure should be — and — to administer and – for routine use
2- — criteria which is of Acceptability, Reliability, Validity, Responsiveness
Particularly relevant to QoL measures, screening and diagnostic tests, etc.
practical
simple n brief
feasible
psychometric criteria
How much disease and disability is out there?
This is a question that can be asked by many people for many reasons
A person might want to know what is my risk of suffering a stroke?
A family doctor might want to know how many people with type I diabetes will I be treating in my practice?
A hospital might want to know how many heart attacks will occur in our catchment area each year?
all of these question can be answered by measuring the — of diseases and different measures answer different questions
rate
question 1: how many ppl have the disease
point prevalence formula is:
point prevalence could use — aka community survey as in HPV status (7.2%)so it shows point perfalcne for each age group.
the problem w point pervalence is some condition — or — as headaches colds flu n depression So the number who have the problem on a particular day may under-represent the number who suffer from the problem
point prevalence = no.of cases at a point of time/ total number of persons at the post in time.
cross sectional study
fluctuate or short lived
The number of people who have suffered from a problem within a specified time period is called the —
period prevelance which is calculated by:
point prevalence = no.of cases at the time of the study period/ no.of ppl at risk at the start of study
prevalence tell us the — of the ideas in the population at a given time.
it toys useful as an index of the – of the population
and its useful for measuring the —
- burden of disease
- health
- demand for health services
question 2: how requecmtly are new cases occurring
- prevalence shows us the – of disease in a population at the given time
but it doesnt tell us the — at which the new cases are appearing
the rate of occuercne of the disease is known as —
level
rate
incidence
no of new cases within a given time period / no. of ppl at risk at the start of the time period =
cumulative incidence ( so we excluded the ppl who had the disease from the beginning n we only include new cases)
- an example is from framingham study as:
Results from the Framingham study, a pioneering population cohort study.
By 10 years after enrolment in the study, 10% of the women and 20% of the men had suffered a first heart attack.
At 20 years, this had risen to 30% of women and 40% of men,
While at 30 years, 50% of women and 60% of men had experienced a first heart attack
the cumulative incidence tell us:
1- how many — will emerge over time
2- useful if you run a serve that engages patient over — periods as diabetes oncology and cardiology
3- but is to as useful for conditions that may happen – to the – person as heart attack self harm flu
new patients
long periods
repeatedly
same person
Tells us the rate of events per person-time (often per person-year) is known as —
incidence density which = no. of new events within a given period of time/ total person at risk
( check slide 18 for example )
The total number of episodes ÷ Total amount of follow-up is the —
which is reported by — or —
incidence density ( new events NOT new cases)
per day and per year
incidence density tells us:
- useful for diseases that –
- gives us an index of the — of the illness
3- —-tells us how many ppl suffer
4- —- tells us how much suffering these ppl experience
- inidicent density is useful for:
-planning an — and other services that responds to –
- measuring the — of the illness
recur
total burden
cumulative incidence
incidence density
ambulance service
events
total burden
what are the types of measurements:
1- Point Prevalence, Period Prevalence and Cumulative Incidence are all —
2- incidence density is — which is often described as —
proportions
rate
incident rate ( (although, confusingly, incidence rate is sometimes used to describe cumulative incidence)
CHECK SLIDE 28
—: someone w the disease ( as how many ppl have diabetes ) as 3 ppl from 10 ppl in this whole room
— : complication of diabetes , how many times has the patients developed this complication
case ( 3/10 )
event
( that’s the difference between them )
complementary figures : the choice of incidence measure depends on the – of the question
1-If the focus is on how many people, then —is useful
2-If the focus is on how many events then — is more useful
focus
cumulative incidence
incidence density
duration of diseases:
1-Short-lasting diseases have — prevalences compared with their incidence as –
2- Long-lasting diseases will have prevalences — than their incidence as:
3-Preventing death without curing the patient will — duration of disease and — prevalence as treatment of insulin dependent diabetes , HIV
low as cold
high as angina HIC/AIDS
increases duration n prevalence
1- —–: at a given moment, how many people have the disease?
-Good measure of the need for services
2- ——: in a given time period, how many people have the problem?
-A better measure of the public health importance of the disease
3- ——: how many people will develop this disease in a specified period?
-Useful for planning health services and measuring the scope for prevention
4- —–: how many disease events will occur per head of population in a given period?
-Useful if each event carries a risk, to inform need for services and scope for prevention
point prevelence
period prevalence
cumulative incidence
incidence density
A cross-sectional study conducted in November 2013 found that 36% of men and women in the Aseer region of Saudi Arabia were overweight, while 23% were obese (Alzahrani et al, 2016).
What measures of frequency are these?
is an example of:
point prevalence ( bc specific point in time)
—-deals with finding those with a disease in a group of people
Key question: How good is the test at case finding?
— deals with managing the individual patient
Key question: What does a test tell us about an individual?
screening
diagnosis
evaluating a screening test principle:
1- two important jobs:
To identify those —- disease or problem
To identify those —-the disease or problem
2- identify those w the disease:
- The — of the test is the percentage of people with the problem who are correctly identified by the test
3- identifying those without the disease:
-The—- of the test is the percentage of people without the disease who are correctly identified
those w the disease or without
sensitivity
specificity
evaluating diagnostic test principle:
1- — test must indicate that the disease or problem is present
2- — test must indicate that the disease or problem is absent
positive
negative
1-The —– of the test is the percentage of all positive tests that are true positive tests
-The chance that a person with a positive test will actually have the disease
2-The —- of the test is the percentage of all negative tests that are true negative tests
The chance that a person with a negative result won’t have the disease
positive predictive value
negative predictive value
summary :
1—–requires detecting people with a problem in a population
-So questions that start with What proportion of people… are screening questions
-What proportion of people with/without the problem are correctly identified
2—- is about using tests to draw conclusions about a single person
-So questions that start with What proportion of tests… are diagnosis questions
-What proportion of positive/negative tests are right?
screening
diagnosis
