Transcript Folie 1

Epidemiology in
„Sozialmedizin“
Part 1
Based in part on a powerpoint presentation by
Prof. Dr. med. Hans-Werner Hense
Institut für Epidemiologie und Sozialmedizin
Universität Münster
Translated, shortened and added to by Wirsing
Epidemiology is one the foundations
of Health Sciences
Related concepts: What is an epidemic? What is a pandemic? What does it mean when a disease is
said to be endemic?
What is epidemiology?
It is the study of the distribution of diseases (morbidity), invalidity, and
death (mortality) among a population and the various factors associated
with these diseases.
Aims of Epidemiological Research
• Frequencies (descriptive)
• causes (analytical, explaining)
• prognosis (analytical, explaining)
• prevention and intervention,
•Its goal (aim) – is description, explanation, prevention and intervention
Namely at the frequency distribution of specific diseases or deaths according to
(a) people,
(b) time and
(c) place:
a. WHO gets sick or dies – age, sex, socio-economic status?
b. at WHAT TIME period – is there a variation in the disease distribution?;
c. In WHAT COUNTRIES OR REGIONS– is it more prevalent in some areas?
Definition of Incidence rate (= Rate of newly diseased)
The incidence rate tells us how many new cases of a disease
per time unit (e.g. per year) occur within a specific population in relation to all
people „at risk“ – all those who theoretically could fall sick.
Number of Newly Diseased Cases
I = ------------------------------------------------------------Number of people within population at risk
per time
In general, the incidence rate is usually computed per year and per 100, 1 000,
10 000 oder 100 000 persons.
Graphical
Distribution of
Incidence of
Breast Cancer
According to ..
Persons
(age, ethnicity)
And
Place (SF, Hawaii)
The Difference between Prevalence and Incidence
What has an influence on prevalence?
New cases
The number of cases (people) with
a given disease at a given time
Cured
Prevalence Pool
Died
Definition of prevalence rate
The prevalence of a certain disease is determined in a survey by first
finding the number of all affected people in the study population.
The proportion of the population that is affected by a certain disease is
the prevalence rate,
The prevalence rate P is computed:
Number of affected (sick) people
P=
--------------------------------------------------Number of all people in population
Surveys or Prevalence Studies:
What else has an influence on prevalence
Increases Prevalence
Besseres Überleben mit Krankheit
Höhere Letalität
Zunahme der Neuerkrankungen
Abnahme der Neuerkrankungen
Zunahme der allg. Lebenserwartung
Abnahme der allg. Lebenserwartung
Zuwanderung Kranker
Abwanderung Kranker
Abwanderung Gesunder
Zuwanderung Gesunder
Verbesserung der Diagnostik
Vermehrte Heilung
Decreases Prevalence
Surveys or Prevalence Studies:
Who is still sick?
Social Status und Prevalence of Being Sick
Men
Quelle: Nationaler Gesundheitssurvey, Deutschland 1999
Women
Surveys or Prevalence Studies: :
Where is the disease rarer / more frequent?
Country
The 12-month prevalence (%) of asthma symptoms in 13–14 year olds (written
questionnaire) for each centre by selected country
Source: The Lancet 1998
United Kingdom
New Zealand
Australia
Canada
Peru
Brazil
USA
South Africa
Finland
Kenya
Germany
France
Japan
Hong Kong
Spain
Singapore
Ethiopia
Russia
China
Greece
Albania
Indonesia
0%
5%
10%
15%
20%
25%
30%
35%
40%
Epidemiological concepts
morbidity (can be incidence or prevalence)
 morbidity - the rate of illness and disease in a population; usually specified for a given
disease, such as tuberculosis or lung cancer or … Data are collected from insurances or
the Mikrozensus
Mikrozensus has the meaning of "kleine Volkszählung". It is a legally mandated
statistical survey which is done every year since 1957 of 1% of all households in
Germany. It is one of the most important sources of health data
 With the rise of life expectancy and the aging of our society until 2050 we can expect a
rise in the morbidity of the following diseases: diabetes, heart attack, stroke, cancer
(esp. of breast and prostate), dementia, pneumonia, fracture of femur, osteoporosis,
glaucoma, COPD
Epidemiological concepts: mortality
 mortality- the rate or occurrence of death in a population per unit time (e.g. one year);
usually specified for a given disease and a given year. The rate is usually given per
100.000 population size. Data are collected from death certificates and published by the
Statistisches Bundesamt
Here: mortality rates
of a a disease (breast
cancer) according to
country
Other mortality rates
Infant mortality rates in Germany
4,03 infant deaths/1.000 life births
boys: 4,46 deaths/1.000 life births
girls: 3,58 deaths/1000 life births
Infant mortality in Germany: regional and ethnic distribution
The infant mortality differs by region within Germany (2004)
:NRW: 5 infants dead per 1000 life births,
Baden-Württemberg and Bavaria: 3,4 per 1000 life births
Even within the state of NRW there are differences:
3,3 in Rhein-Sieg-Kreis up to 8,7 in Gelsenkirchen
NRW 2004: differences according to citizenship
Infants of German parents:
4,6 deaths per 1000 life births
Infants of parents with foreign citizenship: 11,1 per 1000 life births
Fragen
1.
The prevalence of CHD increases, even though its
Incidence has been sinking for years. How can this be
explained?
1.
Screening for cancer lowers the incidence of cancer
- is this correct?
2.
The number of people in Germany who ever had cancer
is rising continuously.
Is this a sign of bad medical care?
Epidemiological concepts:
Life expectancy at birth
Life expectancy - the average number of years of life remaining at a given age, usually at the
time of birth. It is the average expected lifespan of an individual of a given birth cohort
The life expectancy shows different distributions according to person (sex, social status), region
(country) and time (year)
Since 1950 estimated life expectancy at birth of the world’s population has been increasing
However, in the final 15 years of the 20th century, life expectancy declined in sub-Saharan Africa
and the countries of Central and Eastern Europe (CEE), Russia and other parts of the former
Soviet Union. In Western Europe, in contrast, life expectancy increased between 6-8 years since
1970
Epidemiological concepts:
life expectancy at birth continued
The post-Soviet experience shows that abrupt political, economic and social change can also
have serious adverse effects on population health. The stress and chaos induced in Russia and
other Soviet countries by the collapse of the Soviet Union and the transition from communism
brought in its wake a dramatic and relatively long-lasting decline in life expectancy.
Was meinen Sie: what might have influenced the development of life expectancy over the years
in Europe?
What could explain the usual 6-7 year difference in life expectancy between men and women?
http://web.hszg.de/~wirsing/ASH%20Sozialmedizin09/Questions%20to%20Life%20Expectancy.pdf
Global Changes of Life Expectancies since the 70
http://www.guardian.co.uk/news/datablog/interactive/2012/dec/13/how-people-die-global-mortality-visualised
Since 1970 the LARGEST GAINS in life expectancy have taken place in the
Maldives (27.3 years for men and 29.4 years for women) and improvements in
life expectancy at birth in excess of 20 years were recorded in Bangladesh,
Bhutan, Iran, and Peru.
But life expectancy FELL by one to seven years in Zimbabwe and Lesotho, where
populations were severely affected by HIV/Aids, and for men in Russia, Ukraine
and Belarus, where an alcohol crisis took hold.
Since 1990, the LARGEST GAINS in life expectancy have been in sub-Saharan
African countries, especially Angola, Ethiopia, Niger, and Rwanda, where life
expectancy since 1990 has increased by 12-15 years for men and women,
thanks to more widespread and effective strategies for HIV control and
reduction of childhood diseases
GLOBAL DEATHS, CAUSES
http://www.guardian.co.uk/news/datablog/interactive/2012/dec/13/how-people-die-global-mortality-visualised