Life contingencies
What is life table ?
Life tables are used to describe age-specific mortality and survival rates for a population. A life table is a table which shows, for a person at each age, what the probability is that they die before their next birthday. From this starting point, a number of statistics can be derived and thus also included in the table is:
- the probability of surviving any particular year of age
- the remaining life expectancy for people at different ages
- the proportion of the original birth cohort still alive.
What are the types of life-table ?
1. Cohort or age-specific or dynamic life tables:
a cohort is a group of individuals all born during the same time interval. To prepare cohort specific life table, data are collected by following a cohort throughout its life.
2. Static or time-specific life tables: age-distribution data are collected from a cross-section of the population at one particular time or during a short segment of time, such as through mortality data.
3. Composite - data are gathered over a number of years and generations using cohort or time-specific techniques.
What are the advantages of Life table ?
1. It tells us about the population's strategy for survival,
2. Life tables help us to understand the dynamics of populations.
3. In actuarial insurance, life tables to help price products and project future insured events.
4. It helps determining life-expectancy
Construction of life tables
Age specific mortality rates are applied to a notional population, typically of 100,000. Starting at birth, the probability of dying in each period is applied to the number of people surviving to the beginning of the period, so that the initial figure slowly reduces to zero. The different elements required for a life table include (using standard notations):
Ix
| Number of survivors at age x |
nqx
| Probability of dying between age x and x+n |
nDx
| Number of deaths between age x and x+n |
nLx
| Number of person years lived between age x and x+n |
Tx
| Total number of person years lived after age x |
ex
| Life expectancy at age x |
Ref: http://www.healthknowledge.org.uk/public-health-textbook/health-information/3a-populations/life-tables-demographic-applications
This sort of life table is based on current age-specific death rates for each age or age band used and are called period life tables and are the most frequently used type. In contrast, actual life expectancy of a particular birth cohort can only be calculated when everyone in this cohort is dead. This approach uses a cohort life table and requires data over many years to prepare just a single complete cohort life table.
ExampleAn example of how a life table can be constructed and the mathematics involved can be downloaded from the simple interactive statistical analysis website
http://www.quantitativeskills.com/downloads/#Lifetable [accessed 30/11/2007].
http://www.quantitativeskills.com/downloads/#Lifetable [accessed 30/11/2007].
What is mortality table ?
Mortality tables are based on characteristics such as gender and age. A mortality table gives probabilities based in deaths per thousands, or the number of people per 1,000 living who are expected to die in a given year. Mortality tables are used to help determine premium amounts for life insurance companies, making sure the insurance company will receive enough in premiums and investments to cover the face amounts of the policies it sells.
Time Frame
A mortality table typically covers the time frame from birth through 100 years of age, in one-year increments. You can use a mortality table to look up the probability of death for someone of any age. As you age, the probability of your death increases.
Health Adjusted Life Expectancy (HALE)
This is calculated by subtracting from the life expectancy a figure which is the number of years lived with disability multiplied by a weighting to represent the effect of the disability.
If A = years lived healthily
B = years lived disability
A+B = life expectancy
A+fB = healthy life expectancy, where f is a weighting to reflect disability level.
N.B. This raises all sorts of moral questions on who defines and measures disability level and how they do it.
What is DALY?
Disability Adjusted Life Years (DALY)
Conversely, DALYs combine death and years lived with disability to estimate the burden of disease on populations, and DALYs were used in the Global Burden of Disease study to enable mortality and morbidity comparisons across countries. Weightings were applied to conditions by using the time trade off approach, in which people were asked to consider living more years in imperfect health compared with fewer years in perfect health. The study also placed more weight on the life of a young adult compared with a new born. http://www.who.int/healthinfo/bodproject/en/index.html [accessed 30/11/2007].
Potential Years of Life Lost (PYLL)
A measure related to HALE and DALY, this measure attempts to quantify the potential years of life lost by looking at average age of death from conditions compared to average life expectancy. PYLL can be expressed absolutely or as a rate relative to the population at risk.
Other applications
Other characteristics can also be used to distinguish different risk factors for life expectancy, such as smoking-status, occupation, socio-economic class, and others. More complex analyses for assessing cancer survival, that involves comparisons between two populations or a population in two points in time can also be undertaken.
This is calculated by subtracting from the life expectancy a figure which is the number of years lived with disability multiplied by a weighting to represent the effect of the disability.
If A = years lived healthily
B = years lived disability
A+B = life expectancy
A+fB = healthy life expectancy, where f is a weighting to reflect disability level.
N.B. This raises all sorts of moral questions on who defines and measures disability level and how they do it.
What is DALY?
Disability Adjusted Life Years (DALY)
Conversely, DALYs combine death and years lived with disability to estimate the burden of disease on populations, and DALYs were used in the Global Burden of Disease study to enable mortality and morbidity comparisons across countries. Weightings were applied to conditions by using the time trade off approach, in which people were asked to consider living more years in imperfect health compared with fewer years in perfect health. The study also placed more weight on the life of a young adult compared with a new born. http://www.who.int/healthinfo/bodproject/en/index.html [accessed 30/11/2007].
Potential Years of Life Lost (PYLL)
A measure related to HALE and DALY, this measure attempts to quantify the potential years of life lost by looking at average age of death from conditions compared to average life expectancy. PYLL can be expressed absolutely or as a rate relative to the population at risk.
Other applications
Other characteristics can also be used to distinguish different risk factors for life expectancy, such as smoking-status, occupation, socio-economic class, and others. More complex analyses for assessing cancer survival, that involves comparisons between two populations or a population in two points in time can also be undertaken.
Life expectancy refers to the average period that a person may expect to live. It is the probable number of years remaining in the life of an individual or class of persons determined statistically, affected by such factors as heredity, physical condition, nutrition, and occupation..
Health expectancy:
Healthy Life Expectancy is the average number of years that a newborn can expect to live in "full health" — in other words, not hampered by disabling illnesses or injuries. Medical experts often refer to this as "HALES" (pronounced haleys), or "health-adjusted life expectancy.". WHO defines health expectancy as Average number of years that a person can expect to live in "full health" by taking into account years lived in less than full health due to disease and/or injury.
Indicators:
Household data includes a household roster, health insurance coverage, health expenditures, and indicators of permanent income or wealth. Individual level data include sociodemographic information, health state descriptions, health state valuation, risk factors, chronic conditions, mortality, health care utilization, health systems responsiveness and social capital.
Life table study for Psychiatric disorders
1. Depression
2. Survey method
3. Schizophrenia
4.
WORLD PSYCHIATRY REPORT
Collection from WHO
During and after emergencies, people are more likely to suffer from a range of mental health problems.
Some people develop new mental disorders after an emergency, while others experience psychological distress. Those with pre-existing mental disorders often need more help than before.
WHO-recommended psychological first aid involves humane, supportive and practical help to people who are suffering after a crisis. This support should be provided to people in ways that respect their dignity, culture and abilities. It covers both social and psychological support.
Psychological and psychiatric help need to be made available immediately for specific, urgent mental health problems as part of the health response.
Communities affected by emergencies need long-term access to mental health care as adversity is a potent risk factor for a wide range of mental health problems.
Impact of emergencies
Some problems are brought on by the emergency, some by the response to the event, and others are pre-existing or more serious.
- Significant social problems are:
- emergency-induced: family separation, safety, discrimination, loss of livelihoods and the social fabric of everyday life, low trust and resources;
- humanitarian response-induced: overcrowding, lack of privacy in camps, loss of community or traditional support;
- pre-existing: belonging to a marginalized group.
- Problems of a more psychological nature are:
- pre-existing: people with depression, alcoholism or severe mental disorders such as schizophrenia;
- emergency-induced: grief, distress, alcohol and substance abuse, depression and anxiety, including post-traumatic stress disorder (PTSD);
- humanitarian-response induced: anxiety due to a lack of information about food distribution, or how to obtain other basic services.
Symptoms of distress
Some common ways that people show their distress in reaction to a crisis are:
- physical symptoms: headaches, fatigue, loss of appetite, aches and pains;
- crying, sadness, grief;
- anxiety, fear;
- being on guard, or jumpy;
- insomnia, nightmares;
- irritability, anger;
- guilt, shame (so-called survivors guilt);
- confused, in a daze;
- withdrawn, or very still (not moving);
- disorientation (not knowing their name or where they are from); and
- not being able to care for themselves or their children.
Not everyone who experiences a crisis will need or want support.
Most people will recover well over time, if they are able to restore their basic needs, find ways to return to normalcy, and get some support when they need it. Access to clinical management is important whenever symptoms interfere with daily functioning.
Effective emergency response
- Evidence and experience show that people who feel safe, connected, calm and hopeful; have access to social, physical and emotional support; and find ways to help themselves after a disaster will be better able to recover long-term from mental health effects.
- WHO and partners have developed an intervention pyramid – from basic services and actions at the base to highly specialized at the top – to help countries match response strategies with community needs and appropriate expertise. For example, clinical mental health services at the apex of the pyramid should be provided under the supervision of mental health specialists such as psychiatric nurses, psychologists or psychiatrists.
- Psychological first aid can be provided by field workers, including health workers, teachers or trained volunteers, and does not always need mental health professionals.
- If trained and supervised, general health care staff members can offer first-line care of mental disorders
Effective community response
- Evidence and experience show that people who feel safe, connected, calm and hopeful; have access to social, physical and emotional support; and find ways to help themselves after a disaster will be better able to recover long-term from mental health effects.
- WHO and partners have developed an intervention pyramid – from basic services and actions at the base to highly specialized at the top – to help countries match response strategies with community needs and appropriate expertise. For example, clinical mental health services at the apex of the pyramid should be provided under the supervision of mental health specialists such as psychiatric nurses, psychologists or psychiatrists.
- Psychological first aid can be provided by field workers, including health workers, teachers or trained volunteers, and does not always need mental health professionals.
- Distressed people can benefit from psychosocial support during or immediately following an event.
Looking forward: emergencies can build better mental health systems
In spite of their tragic nature, many countries have capitalized on emergency situations to build better mental health systems. The surge of international donor aid combined with increased attention to mental health issues creates opportunities to improve mental health care.
WHO supports sustainable mental health systems
- Sri Lanka was able to capitalize political will and on the resources flowing into the country following the 2004 tsunami to leap forward in the development of its mental health services. Today, this community-based mental health system reaches most parts of the country.
- The influx of displaced Iraqis into Jordan between 2003 and 2007 enabled pilot community-based mental health clinics to be established. The success of these clinics built momentum for broader reform across the country.
- Access to mental health care in general health care facilities is better in many areas of Syria in 2015 than before the war. Before the war mental health care was only available in the large cities. During the war, over 500 primary health care staff have been trained and are providing mental health care in primary care settings.
We know from these and other experiences from around the world that it is possible to build mental health systems in the context of emergencies.
WHO response
WHO is the leading agency in technical advice on mental health and emergencies. In 2015 WHO is operational on mental health in Central African Republic, Guinea, Iraq, Lebanon, Liberia, Nepal, Pakistan, Sierra Leone, Syrian Arab Republic, Turkey, Uganda, Ukraine, West Bank and Gaza Strip, and Yemen.
WHO works globally to ensure that the humanitarian mental health response is coordinated and effective, and that afterwards mental health systems are rebuilt and sustained.
WHO develops and evaluates tools to meet the mental health needs of people in emergencies. These include tools on assessment, psychological first aid, clinical management of mental disorders, and mental health system recovery.
WHO’s advice and tools are used by the vast majority of international humanitarian organizations active in mental health.
The disability-adjusted life year (DALY) is a measure of overall disease burden, expressed as the number of years lost due to ill-health, disability or early death. It was developed in the 1990s as a way of comparing the overall health and life expectancy of different countries.
The DALY is becoming increasingly common in the field of public health and health impact assessment (HIA). It "extends the concept of potential years of life lost due to premature death...to include equivalent years of 'healthy' life lost by virtue of being in states of poor health or disability."[2] In so doing, mortality and morbidity are combined into a single, common metric.
Looking at the burden of disease via DALYs can reveal surprising things about a population's health. For example, the 1990 WHO report[citation needed] indicated that 5 of the 10 leading causes of disability were psychiatric conditions. Psychiatric andneurologic conditions account for 28% of all years lived with disability, but only 1.4% of all deaths and 1.1% of years of life lost. Thus, psychiatric disorders, while traditionally not regarded as a major epidemiological problem, are shown by consideration of disability years to have a huge impact on populations.
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