incidence and prevalence. Medical science

Helps medicos in easy studying with points shortened.

1. INCIDENCE AND
PREVALENCE

2. INCIDENCE
Incidence rate is defined as the number of new
cases occurring in a defined population during a
specified period of time
no of new cases of specific disease
during a given time period
Incidence =
population at risk during that period
×1000

3. Uses
Tocontroldisease
Forresearchintoetiologyandpathogenesis,
distributionofdiseasesandefficacyof
preventiveandtherapeuticmeasures

4. PREVALENCE
Referstoallcurrentcases(oldandnewcases)existingat
agivenpointintime,oroveraperiodoftimeinagiven
population
or
Thetotalnumberofallindividualswhohaveanattributeor
diseaseataparticulartime(orduringaparticularperiod)
dividedbythepopulationatriskofhavingtheattributeor
diseaseatthispointintimeormidwaythroughtheperiod
Twotypes
1.Pointprevalence
2.Periodprevalence

5. Point prevalence
Defined as the number of all current cases of a
disease at one point of time, in relation to a defined
population
Point –day, several days/few weeks
No of all current cases of a
specified disease
existing at a given point in time
Point prevalence =
estimated population at the
same point in time
×100

6. Period prevalence
It measures the frequency of all current cases existing
during a defined period of time expressed in relation
to a defined population
Eg: Annual prevalence
No of existing cases of a
specified disease during
a given period of time interval
Period prevalence =
Estimated mid-interval
population at risk
×100