RATIO is called a proportion is the quotient of two numbers. Example is number of deaths per population

RATE is a ratio involving a time period. The count or measurement is observed over a period and then divided by its base or population of observation.

Incidence Rate -Measure the frequency of

occurrence of the phenomenon during a given period of time. Deals only with NEW cases.

 Prevalence rate -Measures the proportion of the

population which exhibits a particular disease at a particular time. This can only be determined following a survey of the population concerned. Deals with total (old and new) number of cases

Concepts of Incidence and Prevalence

• Also known as attack rate, case, sickness rate morbidity rate

• It refers to newly discovered cases of a particular disease

• It answers the question “how frequent do cases of a particular disease occur during a given period of time”

• Used when dealing with a cute conditions and accidents

 • It refers to the newly discovered

and old cases of a particular disease over a population• Used when dealing with chronic

conditions and disabilities• It answers the question “what

proportion of the group or population is actually ill with a particular disease at a point in time.• Usually determined by means of

survey

CRUDE BIRTH RATE (CBR)

• This is rough of the fertility of the population

• The rate is called crude for the following reasons

• Only live births are counted• The denominator is the total

population which includes children, old people and males

• The rate is expressed in population unit of 1000 to make the figures meaningful

Crude Birth rate= number of live births x 1000

Midyear population

CRUDES DEATH RATE (CDR) • This is a measure of the risk of

dying from all causes in a population

Crude Death rate= number of deaths x 1000

Midyear population

The Crude Birth Rate (CBR) and Crude Death Rate (CBR) are statistical values that can be utilized to measure the growth or decline of a population.

The Crude Birth Rate and Crude Death Rate are both measured by the rate of births or deaths respectively among a population of 1000. The CBR and CDR are determined by taking the total number of births or deaths in a population and dividing both values by a number to obtain the rate per 10000.

For example, if a country has a population of one million and 15,000 babies were born last year in that country, we divide both the 15,000 and 1,000,000 by 1000 to obtain the rate per 1000. Thus the Crude Birth Rate is 15 per 1000.

The Crude Birth Rate is called "crude" because it does not take into account age or sex differences among the population. In our hypothetical country, the rate is 15 births for every 1000 people but the likelihood is that around 500 of those 1000 people are men and of the 500 who are women, only a certain percentage are capable of giving birth in a given year.

Crude Birth Rates of more than 30 per 1000 are considered high and rates of less than 18 per 1000 are considered low. The global Crude Birth Rate in 2005 is 20.15 per 1000.

In 2005, Crude Birth Rates ranged from 8.33 per 1000 in Germany to 51.33 in Niger. The CBR in the United States in 2005 was 14.14 per 1000. Many African countries have very high Crude Birth Rates and women in those countries have a high Total Fertility Rate, meaning they give births to many children in their lifetime.

MATERNAL MORTALITY RATE (MMR)

 

• Measure the risk of dying due to the process of pregnancy, childbirth and puerperium.

• It also measures the adequacy of maternal health services

Maternal Mortality rate= number of deaths due to pregnancy x 1000

Number of live births

INFANT MORATALITY RATE (IMR)

• Measures the risk of dying due to infancy (under 1 year of age)• deaths under 1 year of age/

number of live births x 1000

Infant Mortality Rate= deaths under one year of age x1000 Number of live births

NEONATAL MORTALITY RATE

• Measures the risk of dying in the first four weeks of life of the infant (newborn)

• The number of children dying under 28 days of age divided by the number of live births that year

• ( Number of infant death / number of life birth ) X 1000

FETAL DEATH RATE• Measures the risk of dying before

birth 

PERI-NATAL MORTALITY RATE• The word means around the period

of birth ( a month or more before births and one month after birth)

• Measures the loss of life in later pregnancy and early infancy.

FORMULAS:Common Vital Statistical Indicators Fertility Rates Crude Birth rate= number of live births x 1000 Midyear population General Fertility Rate= Number of live births

x1000 Midyear population of

women 15-44 years of age

Mortality Rate Crude Death rate= number of deaths x 1000 Midyear population

 Specific Mortality rate= number of death in a specified group x

1000

Midyear population of the

same specified group

 Cause-of-Death Rate= number of deaths from a specified cause x

1000

Midyear population

Infant Mortality Rate= deaths under one year of age x 1000 Number of live births

 Maternal Mortality rate= number of deaths due to pregnancy x

1000

Number of live births

 Proportionate Mortality rate= number of deaths from a particular cause x 100 Total Deaths

Swaroop’s Index= Number of deaths among those 50 years and over X100

Total Deaths

Case Fatality rate= number of Deaths from a specified cause x 100

Number of Cases of the same disease

Morbidity Rates

Incidence Rate= number of new cases of disease developing from a period of time X 100

Population at risk of developing the disease

 Prevalence Rate= number of Old and new cases of a disease X

100Population examined

 Sample problem 1:

1. The crude birth rate is equal to the number of live births (B) in a year divided by the total midyear population (P). This number is then usually multiplied by 1000 to arrive at the actual crude birth rate.

 2.Therefore the formula for crude birth rate is

CBR= (B/P)* 1000 3. Example: in 2007, there were 3,250 births in

the city with population of 223,000. Therefore:

CBR=( 3,250/223,000)*1000CBR= 14.57

So there were 14.57 births every 1000 people in the city.

Sample Problem 2:Town A has a total population of

50,000 as of July 1, 1998 (midyear) as per calendar year 1998 (Jan. to Dec.) 600 died. Which formula below should be used to compute crude death?

Answer: 600 x 1000 50,000

Situation : Barangay A has the following data in

year 20061. July 1 population: 254,3162. Live birth: 2,2893. Death from maternal cause: 154. Death from CVD: 3,0295. Death under 1 year of age: 236. Fetal death: 87. Death under 28 days: 88. Death due to rabies: 459. Registered cases of rabies 4510. People with pneumonia: 7911. People exposed with pneumonia: 2,59312. Total number of deaths from all causes:

10,898

The following questions refer to the data above

1. What is the Crude birth rate of Barangay A?

2.What is the cause specific death rate from cardiovascular disease?

3.What is the Maternal Mortality rate of this barangay?

4.What is the fetal death rate?5.What is the attack rate of pneumonia?6.Determine the case fatality rate of rabies

in this barangay?

The following questions refer to the data above

 1. What is the Crude birth rate of Barangay A?

Ans. 9/10002. What is the cause specific death rate from

cardiovascular disease?Ans. 1191/100000

3. What is the Maternal Mortality rate of this barangay?

Ans. 6.55/1000 or 7/10004. What is the fetal death rate?

Ans. 3.49/1000 or 3/10005. What is the attack rate of pneumonia?

Ans. 3.04/100 or 3/1006. Determine the case fatality ratio of rabies in

this barangay?Ans. 100% or 1:1

Table 2. Cases and Deaths of Cholera inLanao del Sur and Zamboanga del Norte, 2002

Age Group

Lanao del Sur Zamboanga del Norte

Cases Deaths CFR Cases Deaths CFRunder 10

years 107 54 55 1210-24 years 156 30 39 3

25 years & over 667 304 97 11

Total 930 388 191 28

Table 2. Cases and Deaths of Cholera inLanao del Sur and Zamboanga del Norte,

2002

Age Group

Lanao del SurZamboanga del

NorteCase

sDeath

s CFRCase

sDeath

s CFRunder 10

years 107 54 50.5 55 12 21.8

10-24 years 156 30 19.2 39 3 7.625 years &

over 667 304 45.6 97 11 11.3

Total 930 388 41.7 191 28 14.6