PHA6121: EPIDEMIOLOGY: MORTALITY AND FERTILITY RATES

Epidemiology

the study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the promotion of health, to the prevention and control of health problems.

Public Health

refers to collective actions to improve population health.

• Surveillance of the health of the population
• Planning and management of appropriate health services

Responsibilities of health care workers:

minute to minute

Health varies from ___ to _____

determinants

Health is determined by levels of _____

disease terms

Health" outcomes are mostly measured in ___

Public Health

looks at populations, rather than individuals

rates

Public health uses ____ as measure of health

- Type of disease and who is affected
- Population statistics
- Rates
- Health services data
- Other data such as water and sanitation, socio-economic data

Type of data used to measure health

Ratio

It express a relation (in degree or number) between two similar things

Proportion

It is a ratio which indicates the relation betweenone thing and the whole

Proportion

The numerator is part of the denominator

Proportion

usually expressed in percentage

Rate

Measures the frequency of disease/events (birth/death) in a population during a specific time period

Rate

It indicates a risk of developing a condition (disease/death)

Rate

It is usually multiplied by fixed number (1000 or 10,000 or 100,000, etc) to avoid fractions

Rate

measure of frequency of the occurrence of a phenomenon

• compare populations with differentnumbers of people at risk;
• calculate expected numbers of cases;
• be used for priority setting betweendiseases.

Rates can be used to:

1. Mortality
2. Fertility
3. Morbidity and risk
4. Combination rates: e.g. DALY

Types of rates

Rates

used to estimate population growth

Crude birth rate (CBR)

roughly estimate the fertility without considering the gender & age of fertility

Population Doubling Time

Number of years for a given population todouble

CAGR%

Population Doubling Time is based on

Age specific fertility rate

relates births to women of a certain age tothe number of women in that age group

Total Fertility Rate

The average number of children eachwoman would bear, if she has experiencedthe age-specific fertility rates of that calendaryear throughout her child-bearing lifespan

Total Fertility Rate

hypothetical; it is a projection using current fertility patterns to project into the future. It attempts to provide an estimate only

Crude Birth

Advantage/ Limitations: Poor indicator of fertility, Denominator includes men etc

General Fertility

Advantage/ Limitations:
Denominator includes only women of typical child-bearing age, increasingly recognized to extend until 49 years

Age-specific Fertility

Advantage/ Limitations: Considers differences infertility at different ages

Total (Period) Fertility

Advantage/ Limitations: Enables comparisons between countries overtime

•Easier to remember
•Better to communicate.
•Listener does not get confused by unnecessary details

Advantages of rounding up or down

Peri-natal mortality rate (PMR)

estimates foetal and child deaths caused by factorsaround births

Peri-natal mortality rate (PMR)

It is unreliable because the data required is difficult to collectand there is sensitivity around birth

Case fatality rate (CFR)

mostly expressed as a percentage but it is aratio. It is not a proper rate (no specific time) orproportion (not all cases included in the denominator)

maternal death

death of a woman while pregnant or within 42 daysof termination of pregnancy, irrespective of the durationand site of the pregnancy, from any cause related to oraggravated by the pregnancy or its management but notfrom accidental or incidental causes

MM Ratio

describes the risk of maternal death relative to thenumber of live births: Two extremes - Afghanistan 1,400 and Greece2/100,000 live births

MM Rate

reflects not only the risk of maternal death perpregnancy or per birth (live birth or stillbirth), but also the level offertility in the population. No figures available

Adult life time risk of maternal death

The probability of dying from a maternal cause during a woman's reproductive lifespan: Two extremes - Afghanistan 1:11 and Greece 1:31,800

Proportion maternal deaths among deaths of females of reproductive age (PMDF)

The number of maternal deaths divided by the totaldeaths among females aged 15-49 years: Two extremes - Afghanistan39.8% and Greece 0.2%

Late maternal death

The death of a woman from direct or indirectobstetric causes, more than 42 days but less than one year aftertermination of pregnancy.

Life expectancy

shows the survival chances of a population

Life tables or mortality tables

list the probabilities (according toage and sex) that a person will die before their next birthday.There are two types period/current and cohort tables

Period/current Table
Cohort Table

Two types of life tables

period life-table

shows the life-expectancy of people of agiven age in a given year, if they experienced that year's age-specific mortality rates for the rest of their lives. This iscommonly used for actuarial purposes (insurance, pension)

Life expectancy

average number of years a person canexpect to live, if in the future they experience the current age-specific mortality rates in the population

cohort life table

shows the actual survival of a group ofindividuals through time starting either at birth or a specificevent such as infection or treatment . This may be used in healthresearch

• in-accurate and incomplete data
• non-uniformity in collecting/reporting
• lack of standardisation regarding cause
• inaccurate age

Specific problems with mortality rates