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Acute Myocardial Infarction 
Acute myocardial infarction is necrosis of a section of myocardial tissue due to ischaemia. It is usually caused by an atheromatous plaque that ruptures or erodes in a coronary artery. The resulting coronary thrombosis partially or completely blocks the flow of blood in the artery. 

Age-specific rate 
An age-specific rate provides a rate for a given age group. It is calculated in the same way as a crude rate with both the numerator (number of events) and denominator (usually mid-year population estimate) based on the same (usually quinary) age group. 
Age-standardisation allows comparison of rates across different populations while taking account of the different age structures of those populations. Failure to take account of differing age structures can be very misleading when comparing rates in different populations. Age-standardisation allows the production of a rate (direct standardisation) or a ratio (indirect standardisation). 

Annual Population Survey 
The Annual Population Survey (APS) is a household survey which involves a sample of around 320,000 annually in the UK. It includes residents living at private addresses but not communal establishments. Data are collected continuously throughout the year based on quarter. It is designed to provide important socio-economic information at local level. 

Atrial fibrillation (AF) 
A heart condition that causes an irregular and often abnormally fast heart rate (1). AF is more likely to occur in people with other conditions such as high blood pressure or atherosclerosis. Although it can affect adults of any age it affects more men than women and becomes more common with old age. About 1 in 200 people aged 50-60 have AF. This rises to around 1 in 10 in people aged over 80 years (2) 

1. NHS Choices. Atrial Fibrillation. [Online]. London: NHS; 2013. 

2. Atrial Fibrillation. [Online]. London 

Attributable fractions (population attributable fractions) 
Attributable fractions are the proportions of all cases (e.g. deaths or hospital admissions) that are thought to be caused by a particular exposure, for example alcohol or smoking. Fractions are calculated for conditions where there is considered sufficient evidence of a causal relationship between the exposure and the disease or injury.



Body Mass Index [BMI] 
BMI is a measurement of a person’s weight, compared to their height. BMI is calculated as weight (in kilograms) divided by the height squared (in metres). Adults with a BMI of 25 or more are categorised as overweight and with a BMI of 30 or more as obese. 


A census is a count of all people and households within a defined area; here it is undertaken for England and Wales with simultaneous censuses in Scotland and Northern Ireland. The data gathered includes information on population, health, housing, employment, transport and ethnicity. In England and Wales it is undertaken every 10 years with the most recent Census conducted in 2011.  The 2021 Census will be predominantly online supplemented by the further use of administrative and survey data. It is anticipated that the 2021 Census will offer comparable data to 2011. 

CHADS2 risk stratification scoring system 
The CHADS2 score is a clinical prediction rule for estimating the risk of stroke in patients with non-rheumatic atrial fibrillation (AF). It can be used to determine whether or not treatment is required with anticoagulation therapy or antiplatelet therapy.  A high CHADS2 score corresponds to a greater risk of stroke, while a low CHADS2 score corresponds to a lower risk of stroke 

Confidence Intervals [CIs] 
Confidence intervals are indications of the natural variation that would be expected around a rate and they should be considered when assessing or interpreting a rate. The size of the confidence interval is dependent on the number of events occurring and the size of the population from which the events came. Generally speaking, rates based on small numbers of events and small populations are likely to have wider confidence intervals. Conversely, rates based on large populations are likely to have narrower confidence intervals. 

Confidence limits 
The upper and lower boundaries of the confidence interval. 

Crude rate 
A crude rate is the number of events occurring in a population over a specific time period, often expressed as the number of events per 100,000 of the population.  Both the numerator (number of events) and denominator (usually mid-year population estimate) are based on the same geographical area and time period.


Characteristics of a population such as size, distribution and vital statistics. 

Deprivation measures 
Indicators which estimate the level of deprivation in a given area (see also Welsh Index of Multiple deprivation). 

Disability-adjusted life years (DALYs) 
The sum of years of life lost (YLL) and years live with disability (YLD). One DALY can be thought of as one lost year of "healthy" life. The sum of these DALYs across the population can be thought of as a measurement of the gap between current health status and an ideal health situation where the entire population lives to an advanced age, free of disease and disability. 

Drinking above guidelines 
The current guideline for both men and women suggests drinking no more than 14 units a week on a regular basis. 


Emergency Department Data Set (EDDS) 
The EDDS is a patient level data set which was first introduced on 1st April 2009. It contains data on emergency department (ED) attendances. 

An ethnic group is defined as a social group that shares a common and distinctive culture, religion, language, or the like. 

European age-standardised rate 
The European age standardised rate represents the overall rate you would get if the population had the same age-structure as a theoretical standard European population (direct age-standardisation). In order to calculate this we apply the rates which occur in each age band to the new (standard) population structure. The measure only allows for comparison between rates which have been standardised; it is not a proportion or risk of an event occurring and does not, of itself, involve a comparison with rates across Europe. See  age-standardised rate for further details. 


Fifths of deprivation 
Geographical areas are ranked from highest to lowest by deprivation score and then split into five equal bands, ranging from least deprived to most deprived fifth. 



General Fertility Rate [GFR] 
Live births per 1,000 women aged 15-44 years. 

GP cluster 
A small group of GP practices working collaboratively to develop services in the community. GP clusters typically each serve a population of between 30 and 50 thousand patients. The concept of ‘GP clusters’ was first set out in ‘Setting the Direction’, the Welsh Government’s primary & community services strategic delivery programme


Health assets 
Health assets are factors which promote a positive action to improve health and well-being by building on the inherent resources of individuals, families and communities. 

Health board 
Health boards (known offically as local health boards) are the NHS bodies in Wales responsible for the health of the population within their geographical area. They are responsible for planning, designing, developing and securing the delivery of primary, community, in-hospital care services and specialised services. There are seven health boards in Wales, changed from 22 local health boards (LHBs) and seven NHS Trusts previously. On this web site the abbreviation LHB is only used in historic work referring to the previous 22 local health boards. 

Healthy life expectancy 
The average number of years an individual of a given age is expected to live in good health, if current age-specific mortality rates continue to apply. 

Heavy (binge) drinking 
For men, this is drinking more than 8 units on a day in the previous week. For women, this is drinking more than 6 units on a day in the previous week. 

High blood pressure or hypertension is a major risk factor for cardiovascular disease. It is one of the most important and preventable causes of premature morbidity and mortality in developed and developing countries. Hypertension rarely has obvious symptoms. Studies show it is often under diagnosed. The chances of having hypertension increase with age. 

Hypotheses usually come in pairs as a null hypothesis and an alternative hypothesis. Both relate to possible explanation of a phenomenon. The alternative hypothesis proposes an explanation for the phenomenon, whilst the null hypothesis refutes that explanation. For example, an alternative hypothesis might be that lung cancer is caused by tobacco smoking, whilst the null hypothesis might be that lung cancer is not caused by smoking. A study would be conducted to evaluate the competing hypotheses.


Inverse care law 
The inverse care law is a theory that proposes “The availability of good medical care tends to vary inversely with the need for it in the population served”. The quality of the medical care, as well as its presence or absence, is central to the theory. Originally formulated by Dr Julian Tudor Hart in 1971 whilst working as a GP near Port Talbot. 






Life expectancy 
The average number of years an individual of a given age is expected to live if current age-specific mortality rates continue to apply. 

Life expectancy decomposition 
The contribution of different age bands or causes of deaths to change in life expectancy over time (due to changes in age or cause specific death rates) can be calculated using a method of ‘life expectancy decomposition’. Contributions to changes in life expectancy over time show the amount that life expectancy has increased in the later time period due to changes in the mortality rate since the earlier time period in a given age group or cause of death, assuming all other rates remained constant. Contributions that increased life expectancy (that is, where mortality rate has reduced over time) have a positive value, while contributions that offset the life expectancy increase (that is, where mortality rate has increased over time) have a negative value. 

The same decomposition method can also be used to assess the contribution of different age bands or causes of death to differences (or the gap) between areas with different levels of deprivation. 

List size 
The number of patients registered with the general medical practice 

Local Health Board [LHB] 
See health board.

Low birth weight 
Babies born weighing less than 2,500g. 

Lower Super Output Area [LSOA]     
Defined geographical area based on Census output areas with an average of 1600 persons per LSOA. There are 1909 LSOAs in Wales, and the number of LSOAs can vary widely between health boards.


Mental health 
Good mental health is when a person is able to think, feel and react in ways they need and want to in life. Conversely, poor mental health means that a person might have difficulty with the ways they think, feel and react. 1 One in four people are affected by mental health problems. 2 
1 MIND. What are mental health problems? 2013. [Online] Available at: [Accessed 22nd June 2018] 
2 World Health Organization. Mental health action plan 2013-2020. 2013. [Online] Available at: [Accessed 22nd June 2018] 

Mid-year estimates 
Annual ONS estimates of the resident population, based on the Census and taking into account population change (births, deaths and migration). 

Middle Super Output Area [MSOA] 
Defined geographical area based on Census output areas with an average of 7500 persons per MSOA. There are 410 MSOAs in Wales, and the number of MSOAs can vary between health boards. 


National Public Health Service for Wales 
See Public Health Wales NHS Trust. 

National Statistics Socio-economic Classification (NS-SEC) 
The NS-SEC is an occupation-based classification created by the Office for National Statistics. Its aim is to help explain differences in social behaviour. Whereas deprivation indices such as WIMD are measured at the area level, which means that individuals living within the area can be mis-classified, the NS-SEC has the advantage of being measured at the household or individual level. 

National Survey for Wales 
The National Survey for Wales (NSW) has been conducted by the Welsh Government (WG) since 2012, more recently combining five previous surveys into one (since 2016). It is based on a representative sample of around 11,000 people living in private households in Wales but not communal establishments. The National Survey for Wales provides key evidence on people's views and wellbeing to inform and shape decision-making by public bodies in Wales.


See Body Mass Index (BMI)

Older people living alone 
The proportion of residents within the given geographical area aged 75 and over that live on their own. This indicator is derived from 2001 Census data. 

See Body Mass Index (BMI)


Percutaneous Coronary Intervention 
A non-surgical procedure that uses a catheter to place a stent to open up blood vessels to the heart that have been narrowed by atherosclerosis. 

Population density 
Persons per square km. 

Population projections 
Population projections provide an estimate of the size of the future population and are based on assumptions about births, deaths and migration. The assumptions are based on past trends and only indicate what may happen should the recent trends continue. 

Public Health Wales NHS Trust 
Public Health Wales was established as an NHS Trust on 1 October 2009. The Trust incorporates the functions and services previously provided by the National Public Health Service for Wales, the Wales Centre for Health, the Welsh Cancer Intelligence and Surveillance Unit, and the Congenital Anomaly Register and Information Service for Wales. Its statutory functions cover a broad range of public health, health protection, screening, health intelligence and research services. 

Public Health Wales Observatory 
The Public Health Wales Observatory is a small team within Public Health Wales NHS Trust, with staff skilled in public health data analysis, evidence finding and knowledge management. The Observatory is the place where decision makers and the public can obtain useful public health information about the people of Wales. 

Public Service Boards 
Public Service Boards (PSB) are statutory bodies set up under the Future Generations (Wales) Act 2015 to replace voluntary Local Service Boards in each local authority. Each board will assess the state of economic, social, environmental and cultural well-being in its area and set objectives that are designed to maximise the PSBs contribution to well-being goals. Membership is made up of representatives from the Local Authority, Health Board, the Fire and Rescue Authority and Natural Resources Wales. The following are also invited to participate: Welsh ministers, Chief Constables, The Police and Crime Commissioner, Certain Probation Services and at least one body representing relevant voluntary organisations.


Quality and Outcomes Framework   
The Quality and Outcomes Framework (QOF) is a voluntary system of financial incentives for GP practices. It is about rewarding contracts for good practice (and its associated workload) through participation in an annual quality improvement cycle. 


Registered population 
The number of people registered with a general practitioner within the given geographical area.  An area’s registered population can therefore include people resident in a different area. 

Revascularisation is the process of restoring the flow of blood to the heart to overcome the effects of atherosclerosis in the coronary arteries. The two primary revascularisation techniques are: coronary artery bypass graft and percutaneous coronary intervention. 


School Health Research Network 
The School Health Research Network's Student Health and Wellbeing incorporates the previous Health Behaviour in School-aged Children (HBSC) survey. The survey sampling frame is extensive and more recently includes all mainstream secondary schools in Wales. From this, a nationally representative sample is drawn. The children are asked a range of questions on health and wellbeing, school life, family life, relationships and behaviours. Further information on the survey is available at: 

Short Warwick-Edinburgh Mental Wellbeing Scale (SWEMWBS) 
Similar to the Warwick-Edinburgh Mental Wellbeing Scale (WEMWBS), the Short Warwick-Edinburgh Mental Wellbeing Scale (SWEMWBS) is a scale which measures happiness and to what extent the person is fully functional. For the short version, scoring is between seven and 35. Lower scores indicate lower mental wellbeing and higher scores suggest higher mental wellbeing. The SWEMWBS covers seven of the 14 items in the original WEMWBS. 

Slope index of inequality 
Measures the difference in life expectancy (in years) between the most deprived and least deprived, whilst taking into account the distribution of the population across deprivation groups. 

Smoking-attributable hospital admissions 
The estimated number of hospital admissions attributable to smoking. This indicator is based on a list of diseases published by NHS Digital which are considered more likely to cause fatal and non-fatal diseases in smokers and ex-smokers than in people who have never smoked. 

Smoking-attributable mortality 
The estimated number of deaths attributable to smoking. This indicator is based on a list of diseases published by NHS Digital which are considered more likely to cause fatal diseases in smokers and ex-smokers than in people who have never smoked. 

Spider chart 
Spider charts (also known as radar charts) display a number of indicators each with their own axis which are arranged radially around a central point. The values are shown by the point on the axis and a line is drawn connecting the data values for each point forming a web like structure. 

Statistical significance 
A result may be deemed statistically significant if it is considered unlikely to have occurred by chance alone. The basis for such judgements is a predetermined and arbitrary cut-off, usually taken as 5% or 0.05. In some circumstances this cut–off may be lowered to 1%, for example where there is a greater need for certainty over the safety of a drug or procedure. Statistical significance must not be confused with clinical or other significance. A result may be clinically significant whilst not being statistically significant and vice versa. 


Tableau is a user-friendly business intelligence tool which helps users to explore, visualise, and understand data. 

Type I and type II errors 
In making decisions about whether to reject a hypothesis two types of error are possible: a null hypothesis can be rejected when it is in fact true, or it is possible to fail to reject it when it is false. These are called type I and type II errors respectively. A significance test can never prove that a null hypothesis is either true or false. 


Unscheduled care 
Unscheduled care can be defined as health and/or social care which cannot reasonably be foreseen or planned in advance of contact with the relevant professional. Unscheduled care, by definition, is urgent with the need to take action at the time of contact with services. 

Upper Super Output Area (USOA) 
Defined geographical area based on Census output areas with an average of around 30,000 persons per USOA. There are 94 USOAs in Wales, and the number of USOAs varies between health boards. 


Very heavy drinking 
For men, this is drinking more than 12 units on a day in the previous week.  For women, this is drinking more than 9 units on a day in the previous week.


Warwick-Edinburgh Mental Wellbeing Scale (WEMWBS) 
The Warwick-Edinburgh Mental Wellbeing Scale (WEMWBS) is a collection of 14 questions covering feeling and functioning aspects of mental wellbeing. It consists of 14 statements and asks respondents how often they felt this way on a five-point scale, where 1 is "none of the time" and 5 is "all of the time". A score from 14 to 70 is then subsequently calculated. Lower scores indicate lower mental wellbeing and higher scores suggest higher mental wellbeing. 

Well-being of Future Generations (Wales) Act 2015 
The Well-being of Future Generations (Wales) Act 2015 makes public bodies listed in the Act think more long term, work better with people and communities and each other, look to prevent problems and take a more joined-up approach. The Act makes those bodies listed, carry out their tasks in a sustainable way. The Act also establishes Public Services Boards (PSBs) for each local authority area in Wales. Each PSB must improve the economic, social, environmental and cultural well-being of its area by working to achieve the well-being goals. Furthermore, the Act established a Future Generations Commissioner for Wales, whose role is to act as a guardian for the interests of future generations in Wales, and to support the public bodies in the Act to work towards the well-being goals. 

Welsh Index of Multiple Deprivation (WIMD) 
WIMD is a measure of multiple deprivation at lower super output area level. A WIMD deprivation score is calculated using eight domains i.e. income, employment, health, education, access to services, housing, physical environment and community safety. 




Years lived with disability (YLD) 
The number of incident cases in the period is multiplied by the average duration of the disease and a weight factor that reflects the severity of the disease on a scale from 0 (perfect health) to 1 (dead). 

Years of life lost (YLL) 
The number of years of life lost due to premature mortality






Accident and Emergency 


Annual District Birth Extract 


Annual District Death Extract 


Association of Public Health Observatories 


Annual Population Survey 


Ask TRIP to Rapidly Alleviate Confused Thoughts 


All Wales Injury Surveillance System 


Black and minority ethnic 


Body Mass Index 


Child and Adolescent Mental Health Services 


Collaboration for Accident Prevention and Injuries Control 


Congenital Anomaly Register and Information Service 


Communicable Disease Surveillance Centre 


Coronary heart disease 


Confidence interval 


Chronic Kidney Disease 


Chief Medical Officer 


Child Measurement Programme 


Chronic obstructive pulmonary disease 


Coverage of Vaccination Evaluation Rapidly 


Cardiovascular disease 


Disability-free life expectancy 


European age-standardised rate 


Endoscopic retrograde cholangiopancreatography 


General fertility rate 


General Practitioner 


Health Board 


Health Behaviour in School-aged Children Survey 


Healthy life expectancy 


Health needs assessment 


Health Solutions Wales - part of the NHS Wales Informatics Service (NWIS) 


International Classification of Diseases 10th Revision 


International Obesity Task Force 


Local authority 


Life expectancy 


Local health board 


London Health Observatory 


Lower super output area 


Measles, mumps, rubella 


Middle super output area 


Mid-year population estimate 


Non-alcoholic fatty liver disease 


National Centre for Social Research 


Newborn Hearing Screening Wales 


National Community Child Health Database 


National Institute for Health and Care Excellence 


National Public Health Service for Wales (a predecessor organisation to Public Health Wales) 


NHS Wales Informatics Service 


North West Public Health Observatory 


Office for National Statistics 


Obstructive Sleep Apnoea Hypopnoea Syndrome 


Patient Episode Database for Wales 


Public Health Mortality 


Public Health Outcomes Framework 


Public Referral Unit 


Public Service Board 


Quality and Outcomes Framework 


Smoking – Attributable Mortality, Morbidity, and Economic Costs 


Sudden infant death syndrome 


Slope Index of Inequality 


Stop Smoking Wales 


Sexually transmitted infection 


Sexual health in Wales Surveillance scheme 


Upper super output area 


University/Teaching Health Board 


Vaccine Preventable Disease Programme 


Vital statistics 


Welsh Assembly Government 


Welsh Assembly Health Information Monitoring Service 


Wales Centre for Health (a predecessor organisation to Public Health Wales) 


Welsh Cancer Intelligence and Surveillance Unit 


Welsh Demographic Service 


Welsh Examinations Database 


Welsh Government 


Welsh Health Circular 


World Health Organisation 


Welsh Health Survey 


Welsh Index of Multiple Deprivation 


Welsh Initiative for Stillbirth Reduction 


Welsh National Database for Substance Misuse 


Welsh Oral Health Information Unit