This document discusses various epidemiological terms used to measure disease frequency and distribution in a population. It defines rate, ratio, and proportion as different ways of comparing two quantities, with rate expressing the occurrence of an event over time, ratio comparing the relative sizes or values of two quantities without a time component, and proportion expressing one quantity as a percentage of the whole. It also defines various epidemiological measures including incidence, prevalence, attack rate, case fatality rate, and different types of mortality rates.

2. Disease Disease frequency.
frequency.
Distribution
Distribution.
determinants.
Determinants.

3.  Mortality.
 Morbidity.
 Disability.
 Presence & absence or distribution of..
 Medical needs.
 Utilization of health services.
 Demographic variables.

4. Rate
Ratio
Proportion

5.  Measures the occurrence of an event or
disease in a given population during a
given period (one Year).
(Birth rate, growth rate, accident rate)
 Usually expressed per 100 or per1000
population.
 It has a time dimension, whereas a
PROPORTION does not.

6.  A fraction is made up of 2 numbers.
 The top number is called the
NUMERATOR
 and the bottom number is called the
DENOMINATOR.
 In the fraction ¾ the 3 is the numerator
and the 4 is the denominator.

7. No of death in one year
 Death rate= -------------------- X 1000
Total mid year population
Numerator
Denominator.
Time specification
Multiplier
(Numerator is part of denominator )

8.  The value obtained by dividing one
quantity by another- X/Y.
 Male to female ratio.
 A ratio often compares two rates,
death rates for women and men at a
given age.

9.  Ratio also expresses relation of size
between the two quantities.
 Numerator is not part of Denominator.
 Expressed as X / Y.
Doctor : Population ratio.
Male : Female ratio.
WBC : RBC ratio

10.  A part/share or number considered in
comparative relation to a whole.
 "the proportion of greenhouse gases
in the atmosphere is rising”
 Usually expressed as a percentage %

11.  This is also relation /magnitude between
two quantities, And numerator is always
part of denominator.
 And expressed as percentage
-Proportion of female students .
-Proportion of anemic mothers
(60% mothers are anemic)

13. Incidence
Occurrence of new cases
•
Prevalence
Existence of all new & old cases.

14.  Prevalence:- how many people in
a population currently have the
disease (Photograph)
 Incidence:- how many people are
diagnosed each year (Film)

15. Cure rate

16. New cases

17. • The rate at which acute
disease is spreading --
used during epidemics
& expressed in %.
Attack rate
• % of exposed persons
developing disease after
primary case exposure
Secondary
attack rate

18. •Prevalence at any
given point of time.
• 4% TB cases on 1st April
Point
prevalence
•Prevalence at a given
period of time.
•Period will be 1year.
Period
prevalence

19.  Longer duration of the disease.
 Prolongation of life, with treatment.
 If incidence increases.
 Immigration of new cases.
 Better reporting of cases.
 Emigration of healthy people.

20. Longer
duration of
disease
Incidence
increases.
Prolongation
of life
without
cure.
20

21.  Shorter duration of diseases.
 Improved cure rate.
 Incidence decreases.
 Emigration of new cases.
 Under reporting of cases.
 Immigration of healthy people.

22. Improved cure rate.
Short duration of
disease.
Incidence decreases

24.  Crude Death Rate.
 Specific death rate.
 Case fatality rate.
 Proportional mortality rate.
 Survival rate.
 Standardized death rate.

25.  Number of deaths from all causes, per
1000 estimated mid year population in
one year in a given place.
No deaths during one year
CDR = _________________________ X 1000
Mid year population

26.  Cause Specific death rate like
disease death rate, Road accident…
 Age specific-IMR, Child Mortality rate
 Sex specific death rate – MMR/female
 Period specific death rate–Death in May

27.  Percentage of particular cases dying
during particular disease epidemic.
 Killing power of disease particularly
acute diseases
No of deaths due to cholera
 CFR= ----------------------- X 100
Total No of cholera cases

28.  Proportion or % of deaths due to
particular cause out of total deaths.
 It measures the disease burden.
 Under 5, No of deaths below 5 years
proportional = -------------------- X 100
mortality rate Total No all of deaths

29.  Percentage of the treated patients remaining
alive at the end of 5 years treatment.
 Yard stick for assessing the standard of
therapy in cancer.
 Survival pts alive at the end of 5 yrs
Rate = ---------------------- X 100
Total No of pts treated

30.  CDR can not be useful for comparison.
 Death rate need to be standardized
for comparisons.
 Standardization can be done by-
:adjusting death rate age wise,
:also can be done sex/race wise