GP Flashcards
pack years
pack years = 20
number smoked per day /20 (x years smoked)
alcohol units
units =
(volume in ml x ABV %) / 100
lites to ml
x 1000
ml to litre
/ by 1000
evidence of research (best to least trustworthy)
- systemic review
- randomised control (double blind)
- cohort
- case reports
- expert opinion (last)
what is publication bias
only positive /significant findings get published
what is the response bias?
people alter their response for whatever reason (memory issues, social pressure, what they think the people want to hear)
surveys mostly affected
what is selection bias
affects how particpants are choosen - from groups not representative of the entire population
what is confounding bias
a hidden third factor
- (that influences both exposure and outcome)
creates a false association between them
what is detection bias
differences in how outcomes are MEASURED
between study groups
measurements may favor one group over aother
(e.g. leading to misleading conclusions)
**follows 2 groups over time **
to see who develops the outcome
cohort study
e.g. following smokers and non-smokers to see who will get lung cancer
expensive and time consuming
selection bias/recall smaller
the number of new cases of a disease that occur in a specific population during a specific time period.
incidence (NEW CASES ONLY)
number of new cases/population at risk
x incident rate
e.g. 200 new cases in in population of 50,000, what is the incident rate per 100,000 people
200/50,000 x 100, 000
starts with cases (disease) and
looks back to find exposures
case-control study
e.g. comparing lung cancer patients to health people and checking smoking history
cheap/fast
high recall and selection bias
measures exposure and outcome at
a SINGLE POINT IN TIME
snap shot in time
cross sectional study
e.g surveying the population to measure obesity and diabetes rates at one point in time
good = quick and inexpensive
bad = selection bias/suvivorship bias
follws the same group over time
to observe changes
longitudinal study
e.g. following the same group of children over years to track BMI changes
good= trends over time
bad = expensive, high dropout rate
the total number of cases (both new and existing) of a disease in a specific population at a particular point in time or over a specified period.
prevalence
If in a population of 100,000 people, 1,000 people are currently living with diabetes (both new and existing cases), the prevalence rate is:
(new + existing cases)
/existing population
xincidence rate per
In a population of 500,000, there are 3,000 people living with chronic hypertension. What is the prevalence rate per 100,000 people?
3000/500,000
x 100,000
=600 per 100,000
