Demographic Transition PDF

DEMOGRAPHIC TRANSITION Lecture 2 College of Nursing, PNU 1 Demography Demography is the study of populations over time and over place. “Demo” means “the people” and “graphy” means “measurement”.  (Demos = population, Graphy = picture)...

DEMOGRAPHIC TRANSITION Lecture 2 College of Nursing, PNU 1 Demography Demography is the study of populations over time and over place. “Demo” means “the people” and “graphy” means “measurement”.  (Demos = population, Graphy = picture) College of Nursing, PNU 2 Demography Importance of Demographic data Health status of a community depends upon the dynamic relationship between number of people, their composition & distribution. Planning of health services can be guided by demographic variables, for example: How many health units do we need? How to distribute them in the community in order to be accessible to the target population? What type of manpower is needed? College of Nursing, PNU 3  Y The elements of demography g Size: increase or decrease Composition: sex and age group Distribution: territory (setting) College of Nursing, PNU 4 The elements of demography Source of demography  Population Censuses  National Sample  Surveys Registration  Vital Events e fl A T ow College of Nursing, PNU 5 Biggest source of data on Demography Economic Activity Literacy & Education Housing & Household Urbanization Fertility and Mortality Language, Religion & Migration Scheduled Castes and Scheduled Tribes College of Nursing, PNU 6 DEMOGRAPHIC PROCESSES It deals with the 5 demographic processes: Fertility Mortality Marriage Migration Social Mobility How a Pironsocial ecu ni mi estuationimproves ordicline overtime College of Nursing, PNU 7  3 The three major components of demography are: Mortality deals with death rates in a population; Fertility involves birth rates in a population; Migration involves the movement of people internally (within a country) and externally (across a country’s borders). College of Nursing, PNU 8  The Demographic Transition The demographic transitionI pertains to changing levels of mortality and fertility in countries over time. The Demographic Transition Model (DTM) What does it mean and what are the reasons behind the trends? College of Nursing, PNU 9  a 5 i College of Nursing, PNU This Photo by Unknown Author is licensed under CC B1Y0-SA CAN YOU ANSWER THESE QUESTIONS? 1. At which stage is the death rate the highest? I 2. At which stage is the natural increase the highest? 3 3. At which stage is there a natural decrease? 5 4. At which stage is population growth the highest? y College of Nursing, PNU 11 CAN YOU TELL HOW DEVELOPED A COUNTRY IS BY LOOKING AT THE DTM? As a country passes through the demographic transition model, the total population rises. Most developing countries are at STAGE 2 OR 3 (with a growing population and a HIGH natural increase). Most developed countries are now at STAGE FOUR. College of Nursing, PNU 12 oneof them Primary data collection: collection is done by the individual by using the methods such as : Observation Interviews Questionnaires Diaries College of Nursing, PNU 13 Census {An enumeration of a population, originally intended for purposes of taxation and military service}. National survey Registration of vital events Demographic studies College of Nursing, PNU 14 ANALYSIS AND INTERPRETATION OF DATA Data is collected directly or indirectly from population. The data collected directed from individuals by face to face survey. Data collected during census. Data related to health from an individual. Data related from an individual. College of Nursing, PNU 15 ANALYSIS AND INTERPRETATION OF DATA from an individual. c I The data which is collected from outside the source (indirect source) such as: Records, Data taken from hospital records, Data taken from census The data collected need to be arranged in table, charts, diagrams, graphs picture College of Nursing, PNU 16  Saudi Arabia 2020 population is estimated at 34,813,871 people at mid year according to UN data College of Nursing, PNU 17 College of Nursing, PNU 18  Saudi Arabia 2020 population is estimated at 34,813,871 people at mid year according to UN data College of Nursing, PNU 19 College of Nursing, PNU 20 Define Epidemiology: The widely accepted definition of epidemiology is: The study of the distribution and determinants of health-related states or events in specified populations and the application of this study to the control of health problems. College of Nursing, PNU 21 Define Epidemiology: The Occurrence of Disease: 8Disease Surveillance and Measures 8 College of Nursing, PNU 22  What is Public Health Surveillance? Surveillance provides the information for descriptive epidemiology, which is Person (age, sex, description) F Place (where) Time (dates, hours, days, months, years) oucrnee of Éollection analysis interptetians of informativeregardin the thedisiece College of Nursing, PNU 23  Surveillance Systems Classified as passive or active Passive surveillance denotes surveillance in which available data on reportable diseases are used, or in which disease reporting is mandated or requested. local and state health departments rely on health care providers or laboratories to report cases of disease. College of Nursing, PNU 24 Surveillance Systems Passive surveillance Primary advantage is efficiency: simple and inexpensive Disadvantage is possibility of incomplete data due to underreporting When passive reporting is used, local outbreaks may be missed because the relatively small number of cases often ascertained becomes diluted within a large denominator of a total population of a province or country. College of Nursing, PNU 25  Active surveillance Active surveillance staff are recruited to carry out a surveillance program. Reporting is generally more accurate when surveillance is active Local outbreaks are generally identified. But active reporting is more expensive to maintain than passive reporting and is often more difficult to develop initially. College of Nursing, PNU 26  Why Is Surveillance Important ? Surveillance information has many uses: Monitoring disease trends Describing natural history of diseases Identifying epidemics or new syndromes Monitoring changes in infectious agents Identifying areas for research Evaluating hypotheses Planning public health policy Evaluating public health College of Nursing, PNU 27 Mortality indicators Morbidity indicators Disability rates Nutritional status indicators Health care delivery indicators Utilization rates Indicators of social and mental health Environmental indicators Socioeconomic indicators Health policy indicators Indicators of quality of life Other indicators College of Nursing, PNU 28  Morbidity has been defined as “any departure, subjective or objective, from a state of physiological well being”. The problem is equivalent to such terms as sickness , illness, disability etc. College of Nursing, PNU 29 The WHO Expert committee noted in its 6th report that morbidity could be measured in terms of 3 units- a. person who is ill ; b. the illness that these persons experienced and c. the duration of these illness. College of Nursing, PNU 30 The following morbidity rates are used for assessing the ill health in the community. Incidence and prevalence Notification rates Attendance rate at outpatient department, health centres ,etc Admission, readmission and discharge rates Duration in hospital and spells of sickness or College of Nursing, PNU 31 Numerator The number of people to whom something happened (i.e. they got sick, died, etc.) Denominator eh The population at risk -- all the people at risk for the event College of Nursing, PNU 32  Counts  Provide an absolute number of the burden of disease  However counts has limited utility for two reasons  The burden of disease in the population is very different if the population size is 100,000 versus 1,000,000  Some people are not at risk for developing a new onset of tuberculosis in 2011 (due to pre-existing infection), thus we need to know not only the size of the total population, but the size of the total population at risk College of Nursing, PNU 33 Ratio In a ratio, the values of X (numerator) and Y (denominator) may be completely independent, or X may be included in Y. Exp: Male/Female Male/All College of Nursing, PNU 34 Proportion A proportion, the second type of frequency measure, used with dichotomous variables, is a ratio in which X is included in Y. A fraction providing a denominator to describe the count in a group Numerator is contained in denominator A / A+B Exp: Male/Female Male/All College of Nursing, PNU 35  Rate Is often a proportion, with an added dimension: it measures the occurrence of an event in a population over time. Usually stated in terms of a unit size of population (often 100,000) for comparability of rates across populations of different sizes The basic formula for a rate is as follows: College of Nursing, PNU 36 Three important aspects of this formula: The persons in the denominator must reflect the population from which the cases in the numerator arose. The counts in the numerator and denominator should cover the same time period. In theory, the persons in the denominator must be “at risk” for the event, that is, it should have been possible for them to experience the event. College of Nursing, PNU 37 Incidence and prevalence  Two measures overcome many of the limitations of a simple count of cases - incidence and prevalence  I Prevalence tells us about the proportion of cases among the total population at any given time  The proportion of people who have the disease (existing cases plus new cases) over the total population for a given time period  The prevalence of a disease is the proportion of Number cases in population at specified time Number of persons in population at that specified time 814 Incidence tells us the probability of a new onset of disease among those at risk for developing the illness College of Nursing, PNU 38 Example: period prevalence Disease occurrence in a sample of 30 people in Riaydh over time Year 1, 5 individuals developed the outcome Year 2, an additional 7 people developed the outcome Year 3, an additional 4 people developed the outcome College of Nursing, PNU 39 What is the prevalence of disease in Year 2?  What is the numerator? 5 cases in Year 1 + 7 cases in Year 2 = 12  What is the denominator? Total sample size = 30  Prevalence = 12/30 = 0.4 The prevalence of disease in Year 2 is 40% College of Nursing, PNU 40 What is the prevalence of disease in Year 3?  What is the numerator? 5 cases in Year 1 + 7 cases in Year 2 + 4 cases in Year 3 = 16  What is the denominator? Total sample size = 30  Prevalence = 16/30 = 0.533 The prevalence of disease in Year 3 is 53.3% College of Nursing, PNU 41 Uses of Prevalence Describing a health burden Health planning/allocation of resources – e.g. treatment, hospital beds, manpower, etc. Estimating exposure frequency College of Nursing, PNU 42  Incidence rate is defined as : “the number of NEW cases occurring in a defined population during a specified period of time”. It is given by the formula. Incidence= no of new case of specific disease during given time period / Population at risk during that period х1000 College of Nursing, PNU 43 Incidence Incidence is a measure of risk of developing disease Number of NEW cases in population DURING specified time Number of persons AT RISK of disease in population during that specified time Example: If the number of new cases of certain disease is 652, and the total population size is 3.81 million, then: 652 I 100,000 3,810,000 .00017100,000  17.1 College of Nursing, PNU 48  Incidence and Prevalence Prevalence Incidence Numerator All cases, no matter Only NEW cases how long diseased Denominator All persons in Only persons at risk population of disease Measures Presence of disease Risk of disease College of Nursing, PNU 49 Measures of Mortality Mortality is the condition of being mortal, or susceptible to death; the opposite of immortality This figure shows the number of cancer deaths up to the year 2011 in the United States. Clearly, the absolute number of people dying from cancer is seen increasing significantly through the year 2011, but from this graph, we cannot say that the risk of dying from cancer is increasing, because the only data that we have in this graph are numbers of deaths (numerators); we do not have denominators (populations at risk). If, for example, the size of the U.S. population is also increasing at the same rate, the risk of dying from cancer does not change. For this reason, if we wish to address the risk of dying, we must deal with College of Nurrsia ng,tPe NUs. 50 Mortality Rates How is mortality expressed in quantitative terms? The first is the annual death rate, or mortality rate, from all causes: Annual mortality rate for all causes(per1,000 population) = Total no. of deaths from all causes in1year No. of persons in the population at mid year ×1,000 Note that because the population changes over time, the number of persons in the population at midyear is generally used as an approximation. If we are interested in mortality in specific age group, gender, diagnosis, cause, etc…, we can calculate a rate specifically for that group: e.g. children younger than 10 years College of Nursing, PNU 47  Annual mortality rate from all causes for children younger than 10 years of age (per1,000 population) = No.of deaths from all causes in one year in children