MEDI251 Lecture Notes - Lecture 3: Common Cold, Prevalence, Cumulative Incidence
7 Aug 2018
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Measures of disease frequency (incidence, prevalence, risk, rates) and standardisation
How to quantify disease in populations
• Rate of occurrence of new cases per unit of time
• Number of cases depends on length of interval
•
• Take into account population size:
o
o IR = number of new cases for a given period of time in a given population
(number of people at risk to get disease)
o KNOW
How to estimate population-time
• Population at risk if the people available to be counted in the case
• Will decline over time as people get the disease
•
(see examples)
Incidence Rate (‘Incidence Density’) – IMPORTANT
Document Summary
Measures of disease frequency (incidence, prevalence, risk, rates) and standardisation. How to quantify disease in populations: rate of occurrence of new cases per unit of time, number of cases depends on length of interval, take into account population size: Ir = number of new cases for a given period of time in a given population (number of people at risk to get disease: know. How to estimate population-time: population at risk if the people available to be counted in the case, will decline over time as people get the disease (see examples) Cu(cid:373)ulative i(cid:374)cide(cid:374)ce (cid:894)(cid:858)i(cid:374)cide(cid:374)ce proportio(cid:374)(cid:859)(cid:895: summarises what happens over a defined over a period of time rather than rate, must define period of observation length of time interva, see examples. Prevalence: numerator is existing and new cases, expressed at % (because proportion) Applications of incidence data: help in research aetiology/causality of disease, used to estimate, risk of developing disease, effects of exposure to a hypothesised factor of interest.
