Epidemeology of respiratory diseases Flashcards
What is epidemeology
A part of population health
Incidence, prevalence, mortality
Causes and precipitants
Severity – risk pyramid (sources of information)
Causes and precipitants
Descriptive epidemeology
n descriptive epidemiology, we organize and summarize data according to time, place, and person. These three characteristics are sometimes called the epidemiologic variables.
Incidence, prevalence and mortality meanings
Incidence is all about new cases
number becoming diseased/ total person time at risk in time period
Incidence can measure people or spells. Here, no recurrence in any individual, so incidence (persons) is same as incidence (spells)
Point prevalence:
Prevelance is no longer about new cases, but does ANYONE have the condition of interest atm at the point you are looking at?
No. affected persons in defined population at point in time divided by
No. in the population at the same point in time
Good for chronic, continuous disease
Period prevalence:
Number affected over defined period of time divided by
Number in the population over the same period
this is good for episodic, spell based disease
What is the risk pyramid of disease
A 5-tier pyramid best describes the impact of different types of public health interventions and provides a framework to improve health. At the base of this pyramid, indicating interventions with the greatest potential impact, are efforts to address socioeconomic determinants of health. In ascending order are interventions that change the context to make individuals’ default decisions healthy, clinical interventions that require limited contact but confer long-term protection, ongoing direct clinical care, and health education and counseling.
Interventions focusing on lower levels of the pyramid tend to be more effective because they reach broader segments of society and require less individual effort. Implementing interventions at each of the levels can achieve the maximum possible sustained public health benefit.
There is both recognised and unrecognised stress
helps to increase
diagnostic awareness
new methods of detection
new treatments
illness behaviour
severe and mild disease at the top, no symptoms at the bottom
incidence aggravates already existing disease
remission makes disease go down period into no symptoms phase
relapse again pushes to top of pyramid
Risk pyramid top to bottom
Death-Routine mortality statistics collated from death certificates
Inpatient -Routine admissions
statistics collated from
hospital data
Outpatient
Primary care- GP databases
Prevalence/symptoms-National surveys Research surveys Notifiable diseases Surveillance Disease registers
unaffected/asymptomatic/not recognised-Populations from
census
What are causes vs precipitants
precipitate is a product resulting from a process, event, or course of action while cause is the source of, or reason for, an event or action; that which produces or effects a result.
Causes:
Genetic/environment (eg cystic fibrosis/asthma)
Environment can be in utero or later in life
Infections - eg Pneumonia
Tuberculosis
Bronchiolitis
Smoking-Lung cancer
COPD
Airborne-particles-Mesothelioma
Pneumoconioses
Nutrition
Precipitants:
Infections Smoking Airborne-particles Nutrition Drugs
What are variations by PEOPLE
Marked variations in disease between individuals by:
Age, gender, socioeconomic position, ethnicity
How can they help us?
Help with process of diagnosis (e.g. age)
Can provide clues to causation of disease
Identify groups who will especially benefit from disease prevention
Describe upper and lower respiratory disease
Upper respiratory rhinovirus (common cold) allergic rhinitis (incl hay fever) High burden in general practice
Lower respiratory chronic airways disease (asthma, COPD) acute infections (pneumonia, bronchiolitis, bronchitis, tuberculosis) lung tissue disease (pulmonary fibrosis, sarcoidosis) circulatory (pulmonary embolism) cancers High morbidity and mortality
What are variations by TIME
Short-term especially seasonal
Longer-term trends: period & cohort effects
How can they help us?
Tell us that disease not inevitable
Provide clues in identifying causes of disease
What are potential pitfalls in time trends
Are the trends real? Could there have been:
Changes in ASCERTAINMENT Willingness to seek medical care Ability to obtain it Changes in DIAGNOSIS Changes in customs, fashion Diagnostic equipment Changes in RECORDING of information Changes in POPULATION STRUCTURE (age, gender etc)
In time trend studies the analyses are based on population groups rather than individuals; exposure and outcome not necessarily linked in individuals
There is a possibility of CONFOUNDING
Best way to overcome these problems to carry out a study which will establish whether in individuals the exposure (e.g. aerosol use) is related to the outcome (e.g. asthma death)
What are variations by PLACE and its pitfalls?
Geographic variations occur at different levels :
e.g. ward, countries, global regions
How can they help us?
Tells us that high rates of major common diseases (e.g. asthma) are not inevitable
Provides clues to the nature of biological normality
Provides clues in identifying causes of disease
Are the geographic differences real? Could there be:
Differences in ASCERTAINMENT between regions?
Willingness to seek medical care Ability to obtain it Differences in DIAGNOSIS between regions Local customs, fashion Diagnostic equipment Differences in RECORDING of information Differences in POPULATION STRUCTURE (age, gender etc)
Geographic studies are OBSERVATIONAL studies and provide evidence of ASSOCIATION: need to consider the possibility of `confounding’
Important not to confuse causation and correlation
Pitfalls of ecological studies
In ecological studies the analyses are based on population groups rather than individuals; exposure and outcome not necessarily linked in Individuals
Often groups differ from one another in many ways – always a possibility of CONFOUNDING – `ecological fallacy’
Best way to overcome these problems to demonstrate that important associations seen in individuals as well as groups (case control and cohort studies)
Epidemeology summary
Epidemiology can be used to describe variation in disease by time place and people
These variations can help identify causes, precipitants and risk factors though caution in interpretation needed
Respiratory diseases are a common cause of mortality and morbidity in the UK and globally
Smoking one of most important risk factors for respiratory and other disease globally
Smoking rates declining in Britain and other high-income nations
