Methods for the development of NICE public health guidance (third edition)

Population vector

The population vector includes those elements which affect, impinge, or impact on the total population. States, governments, supra-national organisations and corporations play critical roles. The elements in this vector include the structure of the state, and concomitant legislation, taxation, and the rules and regulation it uses to manage relations within civil society and between civil society and the state. The degree to which the state permits democratic engagement, political and economic freedoms, free speech, the degree to which it is itself fragile or secure, corrupt or efficient sets a context and directly determines positive or negative health outcomes as well as configuring a range of other vectors of health (Espelt et al. 2008). In the UK things like legislation to ensure the wearing of seat belts, the ban on smoking in public places, legislation prohibiting the sales of cigarettes, tobacco and alcohol to persons under the age of 18 are elements in the population vector. Another example of a public health element in this vector from the UK, is enshrined in formal rules and regulations governing road use in the 'Highway code'. In societies which are totalitarian, authoritarian, dictatorial, and the state is not regulated by principles of equality before the law, the impacts on the health and wellbeing of the population are generally in varying degrees malign.

A very significant element in the population vector is the economy including the size and distribution of GDP and incentives offered through the market as well as barriers to opportunity enshrined in market arrangements and practices. Incentives in the market and the regulation of market failure are 2 very significant aspects of the economy and its operation is fundamental to human health. Economic growth, rates of employment and economic freedom promote market opportunity as well as cause damage when people lose their jobs or businesses fail. These things have direct effects on the livelihoods and life chances of people. The extent to which markets are regulated and managed, and the degree to which protection is offered against the vicissitudes of the market are fundamental. As part of the regulatory structure of the economy the taxation system is core. Related public health elements in the vector in the UK include the duty on beer, cigarettes, wine and spirits. The general fiscal structure especially its regressive or progressive qualities, the amount of VAT on food and possibly on different types of food are also good examples of elements in the population level public health vector.

Legislation and rules will be mediated by the degree to which laws and regulations are enforced and are complied with. Just because the population vector is supposedly universal in its reach, it does not follow that there will always be population-wide epidemiological effects. There may be matters of degree, in that some sectors, groups or individuals may seek to avoid the impact of these actors and may be able to resist the effects, but potentially at least such factors reach the total population.

Environmental vector

The second vector is the environmental one. Environmental elements in this vector include all those potentially noxious substances and particles which might be present in macro and micro-environments, like dust, lead, asbestos, and other things associated with industrial, agricultural, transport or construction activities. They may be present in the micro-environments of homes or workplaces or in atmospheres in the wider environment. The environmental vector also embraces meteorological, tidal, and geophysical hazards such as radiation, floods, and drought as well as longer term climatic threats and dangers. It includes microbiological agents, germs, viruses, bacteria, prions and other biological stressors. It includes some psychological stressors and mediators like noise, working conditions, and so on. It also includes transport systems, buildings, homes and the structural organisation of the workplaces and schools. It includes the systems of sanitation and provision of clean water.

Some of this sits as the specialist concern of environmental health professionals, building planners and engineers, microbiologists, geophysicists and meteorologists. The interest of public health is in the detail of these specialties. But it is also the totality of the environmental elements described that provide both a macro and micro context for the world of experience, vulnerability and risk. These factors will be mediated, in part by the actions of the state in the population vector, but also by various economic actors like businesses and trades unions. Some of the hazards in the environment are more amenable to amelioration and control than others, through regulation and management. Others, like climate change, are less easily amenable to control through regulation and legislation.

Social vector

The social vector consists of all those elements and factors which are linked to social, economic and cultural circumstances (and therefore are closely associated with the population vector). They also include the nature of relationships between social groups in civil and economic society. The conventional way of describing the social vector in public health is by way of describing the epidemiological differences between social groups. So class, statuses, ethnicity, age, gender, and disability, religion, caste, tribe are typically the familiar axes of social differentiation, and also the ones where epidemiologically there are plentiful data showing the different health states of different social classes, different ethnic groups and men and women. These social categories and are well known to be correlated in a graded way with almost all health outcomes.

For the purposes of understanding how these groupings work in this vector, it is helpful to see beyond the statistics and the epidemiological aggregations, to the relationships of power, discrimination, disadvantage and exploitation that are the relational correlates of social position. Similarly, these groupings contain within them patterns of social behaviours or what is sometimes called lifestyle. There are groupings or clusters of ways of living associated with social position which are good ecological predictors of future health outcomes and states. Much of the work of medical sociology and social epidemiology has been about plotting the excess morbidity and mortality associated with these social positions and the sub categories of these positions. However, these groupings are not just the manifestation of the way social factors determines health, they are the core of the operation of these elements in this vector (Link and Phelan 2005; Cockerham 2007).

Organisation

Closely linked, practically and conceptually with the social vector is the organisational vector. Most human activity which is not domestic, takes place in social organisations of 1 type or another. Social organisations provide much of the framework or the architecture of social life in institutions like bureaucracies, schools, factories, businesses, clubs, societies, and religious organisations. There are libraries full of detailed descriptions of the structure and functioning of such organisations (Etzioni 1961; 1964; 1968; Burns and Stalker 1961). Clearly they define important parts of the vectors associated with working and environmental factors which impinge directly on health. These were described briefly above in the vector dealing with environmental elements. What this vector does distinctly however, is to provide a causal pathway from the structure of organisations and in particular in the way they function or they behave as actors. This is most easily done in this context by describing the way the organisation of healthcare directly affects health with reference to access to – and exclusion from – services.

These patterns have been famously described as 'the inverse care law' (Tudor Hart 1971). Tudor Hart argued that the need for care varied inversely with the care provided. In other words, those in most need received the worst care and those in least need the best. Tudor Hart saw this as contributing significantly to health inequality. His observation is widely replicated in many healthcare settings, including those where there is no fee for service and care is free at the point of delivery, like the UK.

Tudor Hart's observation at first seems to fly in the face of older evidence which suggested that services were of relatively minor importance when compared to sanitation, housing and nutrition (McKeown 1976). The answer to this apparent contradiction is that historically, and especially in the era of rampant infectious disease, health services probably played a relatively minor role in maintaining the overall health of populations (although they sometimes relieved suffering at the individual level). However, as technologies have improved and become more effective, services have increasingly become a critical variable in health outcomes, health experience and ultimately mortality, at population and at individual level (Bunker 2001). Therefore, services constitute an important gateway to health life chances individually and at population level. The way people can get to the whole range of care, from preventive services to acute and primary care, mediates health outcomes.

There are a number of dimensions within this organisational vector that apply to health services. The first is availability. People can only use a service if it is there. In the UK system there is universal provision. The second is entitlement. In the UK, entitlement is universal regardless of any other social or economic factor. This is not the case in market systems or others which in some way limit entitlement through other mechanisms. Even with universal provision, it does not follow that there will be universal access. So the third element is the service configuration and the way it affects access. Included here are the ways the service is organised, delivered, and the behaviour of the employees in the service to the clients and patients and to each other. Configuration also includes flexibility and responsiveness to the client group, innovation in care and new pharmaceuticals and its ability to implement new ways of working. Fourth is the relationship between the professional and managerial cadres and of both cadres to the bureaucratic or other mechanisms of organisation. In organisational terms, all of these things have a profound impact on effectiveness of care at all levels and all have a profound impact on the way that clients engage with the service (Friedson 1970).

The fifth element is the behaviour of the client groups themselves. For well-documented and rational reasons people make differential use of all types of service. They delay seeking treatment, they avoid preventive opportunities, they overuse services or use them inappropriately. They can act in ways which will not necessarily maximise the benefits they may derive individually from the service and in ways which may diminish the effectiveness of interventions at population level (Mechanic 1962; Becker et al. 1977; Rosenstock 1974).

The interaction of the vectors and human behaviour

The principal elements of human behaviour of particular interest in public health in Britain are: smoking, eating (and associated consumer behaviour), alcohol consumption, physical activity (including active travel), and sexual behaviour. This is because these are the behaviours most closely associated with disease patterns. But in order to understand the interaction between behaviour and the vectors described above, it is important to conceptualise human behaviour beyond strictly speaking health-related behaviours (NICE 2007). Although the social structure shows strong associations with patterns of health and disease, the public health conceptual framework requires not mere association, but causation and needs to embrace behaviour as a whole rather than behaviours directly associated with disease and disease prevention.

The dynamic of causation of disease lies in the interaction between agency and structure (NICE 2007). Giddens (1979; 1982; 1984) argued that society was the product of interaction between individual human behaviour and the social structure. He further argued that the billions and billions of individual human actions produce societal patterns. The patterns repeat themselves to such a degree that structures emerge. Although these structures change, sometimes gradually, sometimes rapidly, individuals are aware of them and orient their actions in line with them (and are constrained by them). The vectors described above are structural. That is, they are components of the social structure. Those vectors (with the possible exception of physical environmental elements) are themselves the product of human behaviour and then in turn impact on it. Even the environmental vectors are considerably affected by human actions, from climate change to the mutations of viruses and bacteria in the face of antivirals and antibiotics.

It is sometimes mistakenly asserted that the structures of society determine human behaviour. It is considerably more complex than that. A completely determinist position, that is, one that fails to acknowledge the power of human agency to be creative and ingenious, inventive and non-conformist as well as more mundane choices in everyday life, is deficient. Behaviour, although patterned and linked to social structure, is still under some degree of human individual control. Behaviour is not pre-programmed according to social position. For example, in 2006, 33% of people in routine or manual occupations smoked compared with 16% of people in managerial or professional occupations. Members of all social groups exceed their energy requirements in the form of calories consumed, against energy used in the form of physical activity. Excessive alcohol consumption is not confined to the poor and manual workers. And many manual workers do enough physical activity to gain health benefits. In other words, notwithstanding well-defined patterns of behaviour at group level and strong associations between social position and health outcomes, this is neither a programming nor a deterministic effect. The social patterns of health and disease are subject to wide degrees of individual and sub-group variation. This variation is in part accounted for by the enormous variability in human behaviour. The important conceptual trick is to find a means of capturing variation but at the same time capturing the pattern. The conceptual vehicles to do this are the 'life course' and the 'life world'. These in turn provide a means to explain causation from the determinants of health to the microbiology of the human body.

'Life course' sociology and 'life course' epidemiology have accumulated a significant body of evidence which shows that from the moment of conception to the moment of death, the human organism accumulates insults and benefits (Kuh et al. 2003). In health terms, these insults and benefits are a kind of health profit and loss account which determines the health state of the individual. Some of these things are biological and are determined by the hereditary structure of the organism and the microbiological environment; others are a consequence of the vectors described above and their interaction with behaviour. They reflect the immediate physical, social, psychological and emotional environment of the growing child, and then the adult. The 'life course' approach also demonstrates that at critical points on life's journey, which are very highly socially patterned, benefits and insults can be greatly magnified, past insults can be cancelled out, and new benefits can come into play. It is also clear that these changes may be self-reinforcing, producing and reproducing patterns of health advantage and disadvantage. Those critical points on life's journey are like gateways or forks in the road, setting in train patterns that may endure and have long-lasting effects.

It is also clear that the 'life course' follows quite distinct patterns for different social groups. The trajectory through life for the child of a single mother in receipt of state benefit in public sector housing in Scotland will be very different to that of a child born to a professional couple in Surrey, and both will be quite different to that of a Bangladeshi girl born in Tower Hamlets and an African-Caribbean boy born in Lewisham. The direction people go at each gateway has a profound effect on their future. The gateways and where they lead are markedly determined by social factors.

On life's journey the experience of benefits and insults to health occur in what some philosophers call the 'life world'. The notion of the 'life world' in the context used here was developed in the work of Schutz in particular (Schutz 1964; 1967; 1970). The notion also draws upon the work of Mead (1934). The 'life world' is a social space, which can be drawn biologically and physically but which is predominantly cognitive and subjective. It is the place where we make our own decisions, decide upon our immediate actions, judge ourselves and others, experience the social structure first hand in the form of opportunities, barriers, difficulties, disadvantage, and it is where our emotions are played out and our feelings are expressed.

Every human being inhabits his or her own personal 'life world'. At its core is the subjective self, which is experienced as a continuous 'self' existing through time and space within a more or less familiar world of places and people. Although the 'life world' is uniquely personal, it is also inhabited by others who are recognised as physically and subjectively similar to, but separate from, the self. These others who inhabit the centre of our 'life world' are those individuals whom we meet and interact with, or think about and relate to, on a recurring basis. The people with whom we share our domestic arrangements, some of our workmates and perhaps friends and family, as well as those who are not intimates or friends but whom we meet with regularly, make up this world. It is the interaction, real or imagined, on a repetitive basis which defines the inner zones of the 'life world'. The level of intimacy is not the crucial issue. It is the repetitive and routine nature of the contacts with others that is important.

Schutz (1967; 1970) conceptualised the 'life world' as a series of concentric circles. The innermost circle is the one where the everyday contacts and routines are highly predictable and are therefore taken for granted. They are salient and immediate and tend most of the time to be the most important. The more distant parts of the 'life world' are inhabited by things and people we can recognise even though we do not know them, and whom we could and would understand were we to meet and interact with them. We therefore have some sense of these persons and things but their impact on us is nil or negligible. Schutz described the concentric circles of the 'life world' as zones of relevance (Schutz 1970). The closer to the centre, the greater the relevance of what goes on there to the 'I'. The values and prescriptions of the circles closest to the centre are important. The stock of knowledge or assumptions that an individual has of those parts of the 'life world' is a crucial resource for making sense of things (Schutz 1967).

It is very important to note that the innermost circle of the 'life world' may not be (and Schutz never suggested it would be) a place that was benign and cosy. It may be violent and bullying. It may be cold and unforgiving. It may be unpleasant and chronically difficult. It will be the place where discrimination and disadvantage, poverty and unemployment are experienced. However, it constitutes the centre of the existence of the person. 'Life worlds' change as individuals move through space and time. Groups of intimates change, children grow up, leave home and move to a more distant part of the individual's 'life world'. New people come into our orbit of friends and acquaintances. The social group in the everyday 'life world' of contacts – direct and indirect, real, imaginary or virtual – is continually in a state of flux. The possible variability is enormous.

Schutz (1967; 1970) believed that central realities and experiences of everyday life are the building blocks of social life and individual behaviour originates and is rationalised and explained in the 'life world'. The experiences and meanings attributed to disadvantage are constructed in the 'life world'. It is the point where social structure impacts on the individual. It is the highly localised manifestation of the social structure and is where that social structure is experienced, is made meaningful and constrains human action in a very direct way.

The 'life world' is the locus of experience: social, psychological and physical. The 'life world' is also about the physical space which we inhabit. It is where the social meets the biological. 'Life worlds' are the point at which stressors are moderated, mediated or exacerbated. It is the point where insults are parried or where they have their noxious effects. It is the point where vulnerabilities translate stressors into physical and emotional damage. It is where immunities – biological, physical or psychological – work their protective powers. Social disadvantage is characterised by the inability or lesser ability to control the 'life world'. Social advantage is characterised by the ability to make control of the 'life world' sustainable.

There are 4 types of resources that help to control the life world. First, there are technical things like skills, knowledge, money and access to services and resources. Second, there are interpersonal resources constituted from the relationships, social support, safety and ease of communication. Third, there are intrapersonal resources – the ability to deal with the emotions of life and its psychological distresses with equanimity or otherwise. Finally there are the resources of being able to make sense of the 'life world', of being able to make it meaningful. If humans can do that, they seem better able to cope with the ups and downs of human existence (Antonovsky 1984; 1985; 1987).

The trajectory through the life course, mediated through the life world, is how structural factors, the vectors, determine health. The 'life world' is where the causal mechanisms of health inequities operate, and the pathways to ill heath can be described. Disadvantage may be viewed as a differential opportunity (life chance) to control one's 'life world' (Weber 1948). Differences between 'life worlds' are the social manifestations of differences in physical life chances. 'Life worlds' operationalise the differential experiences of power, exploitation and access to resources. Where 'life worlds' abut, the experience of discrimination and disadvantage originates, and within the 'life world' the experience of pain and suffering are located. 'Life worlds' also group together and although each one is unique, there are patternings and clusterings which produce shared experiences and what philosophers call intersubjectivity, that is, a shared understanding and set of common meanings. It is the group properties of aggregated 'life worlds', the clustering of similar experiences that produces the patterns of disease which epidemiology eloquently demonstrates. It is because of the individual operation of the factors which are damaging to health that we can observe the causal pathway from the social to the biological. The pattern is manifest in the differential exposure and vulnerabilities to disease and conversely protection from disease which are familiar territory to public health. The summative effect is the degree of total exposure to pathogens and risks. Vulnerability may be biological, reflecting for example pre-existing nutritional status, immunological status, or illness. It may be psychological in that the ability to be resilient to stressors is at least in part a consequence of psychological processes. It will be social in that supportive social relations and economic security for example, are considerably advantageous when dealing with stressors and their absence both amplify and sometimes directly lead to the inability to cope with stressors. It is not possible to predict individual health outcomes, and the reason for this is that the agency structure system is both patterned and has enormous variability. To borrow an analogy from physics, what we are dealing with here is something akin to the uncertainty principle, and as with physics the uncertainty operates at the micro level rather than at the system level.

Equity

Whitehead describes health inequality as 'measurable differences in health experience and health outcomes between different population groups – according to socioeconomic status, geographical area, age, disability, gender or ethnic group' (1992). Inequality is about objective differences between groups and individuals measurable by mortality and morbidity. Whitehead defines 'health inequity' as differences in opportunity for different population groups which result in, for example, unequal life chances, access to health services, nutritious food, adequate housing. These differences may be measurable; they are also judged to be unfair and unjust (Whitehead 1992). Health equity is defined following the WHO Commission on the Social Determinants of Health as 'the absence of unfair and avoidable or remediable differences in health among social groups' (Solar and Irwin 2007). Health inequity is therefore defined as unfair and avoidable or remediable differences.

There are several further important distinctions which need to be included in a discussion of equity. The terms health gaps and health gradients and absolute and relative differences need to be noted. Health gaps simply refer to the difference measured between 2 different individuals or groups say between men and women, or social class 1 and 5. Conventionally a health gaps approach focuses on extreme differences between the most and least advantaged in a society, for example. The measure could be one of mortality, morbidity, or some subjective measure of health state. The fact of difference, aside from the social injustice involved, is of rather less interest than the trends in the differences between different time points, for example, over a period of 1, 5 or 10 years. Imagine 2 groups with different mortality at point time 1. Then let's assume that at point time 2 the difference between the 2 has remained the same. In absolute terms both groups have remained the same. We would also note that over time the relative difference between them had also remained the same.

However, in contemporary Britain we do not see the health states of groups remaining constant over time. What we observe is that in absolute terms all groups tend to show a long run trend to improve. Health improvement has been the order of the day for nearly 2 centuries. So in absolute terms everyone is getting better. However, what also has happened has been, at least over the last 40 years or so, a trend for the health of the higher social classes to improve at a faster rate than the health of the less advantaged, resulting in the poorer becoming worse-off in relative health terms. This is because their health has not improved as quickly as those above them on the social ladder.

The other feature of health inequity is that the absolute differences at any given point in time manifest themselves as a gradient, with each group as we move up the social hierarchy being a bit better off in health terms than the one immediately below them. This gradient shows a remarkable consistency with income and social class, for example. The steeper the gradient at any given time, the greater the differences between people. However, because of the trend over time for health to improve faster nearer the top than at the bottom, the gradient tends to shift, producing relative disadvantage in spite of overall health improvement in the population. This may fluctuate, however, and absolute and relative differences can vary across time (Krieger et al. 2008).

Universal interventions which produce overall health improvement tend to exacerbate this and therefore moderated or targeted interventions are needed in order to make the rate of improvement greater in the more disadvantaged groups. The problem is that this tends to be both more difficult and less cost effective than universal programmes in which the well off make more use of available services. It is also difficult to do in practical terms because the social differences which are the constituent parts of the gradient, are not very well described, and certainly not in sufficient detail to allow pin-point accuracy with interventions to change things. Unfortunately, the factors which lead to general health improvement – improvements in the environment, good sanitation and clean water, better nutrition, high levels of immunisation, good housing – do not necessarily reduce health inequity. This is because the determinants of good health are not necessarily the same as the determinants of inequities in health (Graham and Kelly 2004). It is necessary to distinguish between the causes of health improvement and the causes of health inequities. Both operate through the vectors. There appears to be an almost inevitable process where the better off always benefit disproportionately and earlier when universal interventions are applied (Kelly 2006). Sometimes there is a catching up effect with the less well off making up ground later, but a differential remains (Antonovsky 1967; Victora et al. 2000). It may be argued that the widening differential does not matter as everyone is benefiting to some degree, so the differential is not a reason not to carry out general health improvement. In fact the decision here will need to be made on a case by case basis. Sometimes in some areas of public health work universal approaches designed to produce overall population health improvement will be appropriate, in other cases a focus on the most disadvantaged, and in others a graduated approach across the gradient will be needed. This cannot be decided in advance. It is also important not to define universal and targeted approaches as simple alternatives. Hybrid actions which contain elements of, for example, universal actions with targeted follow through, will sometimes be the most appropriate.

Whether and how particular interventions will impact on sub groups in the population in particular ways is difficult to determine. The present state of the evidence base means that the data available to make such assessments are very limited. In other words, the amount of data available about differential population effects outcomes in different populations is limited because there is a paucity of outcome research in the first place and there is relatively little which deals with subgroups in ways which allow this to be done. Several academic groups are currently working towards the better construction of the evidence base, the Cochrane Collaboration for example, but the real problem lies in the primary research and its analysis. Although data are not infrequently collected on gender and socioeconomic status and age, (although this is by no means universal) the analysis is usually done in such a way that these variables are used to control for confounding rather than to identify differential population effects. This is particularly so at the level of systematic review.

Building the map of public health

In this last section a classification system based on the vectors will be described to map the key areas of interest for CPHE and to develop a means of clarifying the scoping process and topic selection. The starting point for this is a list of key areas of interest for public health. The feature which links these topics together is their connection to the vectors described above and the fact that there are clear social patterns in the epidemiology and gradients in related health outcomes (Cockerham 2007; Bonnefoy et al. 2007). From this starting point it is possible to draw up a list of key general areas – some linked to disease, some to populations, some to behaviours and lifestyle and some to available technologies. This list helps to capture the main, but not necessarily complete, areas of interest (see below).

The main public health areas of interest:

Obviously this list overlaps with some clinical areas and some of the topics which the NICE clinical guidelines programme would concern itself with. Also, there are clear overlaps within the list: diabetes and obesity are closely related and they both overlap with cardiovascular disease, and this in turn impinges on chronic illness. Environmental health abuts and overlaps with housing and transport and so on. However, the purpose is not to build a taxonomy but rather to describe a variety of potential public areas of interest. This pragmatic approach also allows us to extricate ourselves from the argument about whether topic, population or setting ought to be the basis for public health and health promotion. It is all of these things and the list captures that.

The vectors described above: population, environment, society and organisation, can be cross classified with the topics in the list. This allows for different nuances in respect of a topic to be articulated. So with cardiovascular disease, population-level issues directs attention to tax on cigarettes or controlling levels of salt in manufactured food for example, whereas a focus on the organisation would lead attention to the screening or case finding in primary care. To take another example, if the topic was physical activity, a focus on the environment would lead to an emphasis on the natural and built environment and its links to the ability to take exercise, while a focus on the social vector in this topic would lead to an emphasis on the ways in which, for example, young women and some ethnic minority groups find getting active very difficult for cultural and religious reasons. If transport was the topic, then a population focus would be on regulation of traffic and vehicle and pedestrian safety, whereas an organisational focus would lead to the manner in which public systems of transport facilitate accessibility to services, for example. In each of these areas human behaviour plays a part in various ways, and in each of these areas the problem can be interrogated for its equity dimensions, and considerations as to whether the gap, the gradient and the absolute and relative values are the most germane and salient. The complete cross classification produces the following matrix.

Public health activity can be delivered at a number of different levels. These are population, community, organisation/setting, group, household/ family, and individual. It is important to note that outcomes are not necessarily at the same level as the intervention. So population level interventions may have effects at individual and group level, while individual level interventions may have outcomes at population level if done on a wide enough scale.

Each of the potential levels of delivery can be applied to each of the cells in the matrix of programmes. It is helpful then to describe the matrix in 3-dimensional terms where the topics are on the y axis, vectors on the x axis and the levels of intervention on the z axis.

Each of the cells in the 3-dimensional matrix represents a potential subset of public health interventions. Clusters of these interventions constitute programmes. Some of these programmes would constitute a cell or cells in the 3- or 2-dimensional matrix. Some programmes will map onto different parts of the 3-dimensional matrix. The matrix also allows us to plot the pieces of work already completed by the public health team at NICE.

Topic selection and scoping

The purpose of the forgoing discussion is to map the possible areas of NICE's public health work unified by a conceptual understanding of the causal pathways to disease. As far as topic selection goes, the principles are that when an idea is suggested as a possible topic for NICE to produce public health guidance, it will be plotted first in the long list of key topic areas. Then the topic will be assessed against the vectors and then the potential delivery areas will be considered and the behavioural and equity issues articulated. At the point when the briefing paper gets written for the topic advisory workshop the briefing paper will have to determine which of the causal vectors are of prime interest. The extent to which the interaction with behaviour, the 'life world' and the 'life course' will also need to be specified, along with an account of the equity issues involved. The briefing paper will then go on to describe the programme theory and or theories of change which describe the interaction between the vector, the structure, the human behaviour, as a logic model to map the behaviour in the 'life course' and the 'life world' (NICE 2007; Kelly 2006). This will also be the basis for the initial economic modelling. It will provide a total picture of the placement of the topic on the public health map, provide a means of modelling the key behaviours, provide a means of starting the economic modelling, and provide the basis for the start of forensic searching of the evidence base.

Conclusion

This appendix has mapped the key vectors used for the determinants of health and disease that are of interest to public health. The dynamic interactions between the vectors and human behaviour and the ways they operate through the 'life course' and the 'life world' have been developed. The importance of distinguishing between the ideas of health gaps, health gradients and absolute and relative understandings of equity have also been described. This framework, when combined with key public health areas of interest and levels of delivery, provides a means to map the potential areas where NICE can produce public health guidance.