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Reducing Health Inequalities: Implications for Interventions

The book Developmental Health and the Wealth of Nations, edited by Dan Keating and Clyde Hertzman, provides evidence on what factors determine the health, well-being and competence of a population. Parts Three and Four of the book describe both some broad and specific implications of these findings for policy development and program interventions. In terms of the latter, the book's authors summarize available data and highlight some of the more rigorously studied and evaluated interventions primarily conducted in North America. A few of these early intervention programs are listed later in this section.

Diagram : The Drivers of Population Health

The diagram, "Drivers of Population Health," (see Appendix A) illustrates the main determinants of health as layers of influence, one over another. This model, in line with the weight of scientific evidence, emphasizes interactions between the different levels.

At the centre are individuals, endowed with age, sex and genetic factors which undoubtedly affect their health potential, but which are fixed. In contrast to these pre-determined characteristics, early neurological development (neuro-sculpting) is driven by interactions with social circumstances (as illustrated by the layers surrounding the centre).

Surrounding the individuals are layers of influence that, in theory, could be modified:

• Personal behaviour and way of life of individuals (eg. smoking habits and physical activity)

• Preventive approaches might act to change individual risk by intervening with individuals (eg. by encouraging people to give up smoking or changing their diet).

• An individual's social network. Individuals do not exist in a vacuum: they interact with friends, relatives and their immediate community. These can be considered social and community influences.

• Interventions to encourage mutual support among family, friends and community members can facilitate behaviour change and enhance the individual's ability to cope with adversity.

• The wider influences on a person's ability to maintain health include their living conditions and working conditions, food supplies, and access to essential goods and services.

• Interventions in the workplace or the social environment might encourage a climate which promotes healthy behaviour or improved psychosocial conditions and facilitates coping.

• Overall, there are the economic, cultural and environmental conditions prevalent in society as a whole.

• Interventions at the level of social structure, such as social marketing, economic incentives, regulation or legislation, would reduce social and economic inequalities.

Implications for Policy Development and Program Interventions:

1. "Upstream" and "Downstream" Policies: Complementary Action on Improving Population Health

Because the main determinants of health interact with and influence one another as illustrated in the diagram, policies which focus solely on one determinant of health are likely to be less effective if complementary action is not in place which influences a linked factor in another policy area. Therefore, policies and interventions need to be both "upstream" and "downstream."

Upstream: Policies which deal with wider influences on health inequalities such as income distribution, education and social networks. Policies to reduce social inequalities and to promote social networks are part of a strategy to reduce inequalities in health.

Downstream: Policies which have narrower focus, such as changing unhealthy behaviours (making nicotine replacement available by prescription and improving community recreation facilities).

Inequalities by socioeconomic group, ethnic group and gender can be demonstrated across a wide range of measures of health and the determinants of health. Analysis of these patterns and trends can inform the development of policy.

The economic and social benefits of greater equality seem to go hand in hand, as do economic and health benefits. The quality of the social environment is worst where financial deprivation is greatest. Also, societies in which there is a wide gap between the rich and the poor suffer additional social problems such as high rates of crime.

Many studies and analyses have demonstrated the association of increasingly poor health with increasing material disadvantage. At a population level, improvements in income and living standards are clearly associated with improvements in health and life expectancy. Three areas offer opportunities over time to improve the health of the less well off (of the population):

All policies likely to have an impact on health should be evaluated in terms of their impact on health inequalities.

A high priority should be given to the health of families with children.

Further steps should be taken to reduce income inequalities by improving the living standards of low-income households and increasing the availability of health and social resources in low-income communities.

2. Influencing Lifestyle Requires Multi-Layered Policies and Program Interventions

As illustrated in the diagram above, individual lifestyle factors (health-related behaviour) is an important determinant of health and inequalities in health. However, the reasons why individuals adopt one form of behaviour rather than another are complex. They include:

• the influences of early experience on neural and regulatory systems

• the social and economic environment

• work or school

• the cultural milieu

• characteristics specific to the individual.

Thus policies designed to change health-related behaviour need to act at different levels.

3. Taking Into Account the Role of Gender on Health Status

Gender, like socioeconomic status, shapes individual opportunities and experiences across the life course. While many experiences of childhood are similar for boys and girls, they are exposed to different risks. Men and women occupy different positions in the labour market and in the home, which again bring different health risks.

Mortality is greater in males at all ages. Across the whole of adult life, mortality rates are higher for men than women for all the major causes of death. These include cancers and cardiovascular disease. However, the specific cancers vary between the sexes.

• Life expectancy is greater in women than in men.

• Despite their more favourable position with respect to socioeconomic determinants of health, men have higher mortality rates.

• Women have more morbidity from poor mental health, particularly those related to anxiety and depressive disorders. Furthermore, psychosocial health in women is strongly influenced by socioeconomic status.

• Women have much higher rates of disability than men, especially at older ages.

Potential policy implications related to gender issues include:

• reducing death in young men

• improving health of disadvantaged women with young children

• reducing disability in older women

4. Policy and Program Interventions : Intervening Early

While remedial risk factors affecting health occur throughout the life course, childhood is a critical and vulnerable stage where poor socioeconomic circumstances have lasting effects. In other words, while there are potentially many interventions to improve the health in adults of working age and older people, many of those interventions with the best chance of improving mental and physical health outcomes relate to parents (particularly present and future mothers) and children.

There is now an extensive body of research showing that well-designed stimulation programs can improve the healthy development of children.

Interventions to improve maternal and infant health

Research shows that a mother's nutrition has a great effect on her child's later health. Principal determinants of a baby's weight at birth are the mother's pre-pregnant weight and her own birthweight. The need for policies and programs, such as Health Canada's Prenatal Nutrition Program, to improve the health of future mothers is key.

Interventions to Improve the Social and Emotional Support of Parents

Parents caring for children in disadvantaged circumstances are likely to need additional family support if they are to protect their children from the effects of disadvantage. For example, home visiting in the first 2 years of life has been associated with beneficial effects during childhood. The strength of the evidence suggests developing policies that promote the social and emotional support of parents and children (in the form of health visitors, family resource programs and young parent support groups).

Interventions to Modify Early Life Insults

In the Kauai birth cohort study it was found that severe perinatal stresses (i.e. complications of pregnancy, labour and delivery) compromised the physical and psychosocial development of children from low socioeconomic status families, but were successfully buffered in higher status families (Werner, 1989). By 20 months of age, the average "developmental quotient" for low socioeconomic status children who had experienced severe perinatal stress was much below that for similarly stressed children from higher socioeconomic status families. High socioeconomic status, in this case, represents a series of ongoing investments that not only protect health children but can reverse the impact of existing risk

Werner's longitudinal research shows that developmental resources, such as other adults who can act as surrogate parents when there has been difficult parenting in the biological family, often have a significant positive impact.

Intervention Studies in the Postneonatal and Preschool Period

The body of evidence that can be derived from intervention studies in the postneonatal and preschool period suggests that performance in two basic domains of child development, the cognitive and the social-emotional, can be modified in ways which should improve long-term outcomes. Moreover, evidence of long-term follow-up studies strongly support the view that they do improve long-term outcomes.

"Parent-infant stimulation" programs usually start in the first few months or years of life. These programs share certain common characteristics:

• The activities take place at home

• there is voluntary involvement of at least one parent

• the role of the parent in the process of child development is actively reinforced

• positive role models from the local community are promoted

• contact with program staff is frequent

• programs focus on both cognitive and socio-emotional development.

Parent-infant stimulation programs are not the only ones that effect cognitive and socio-emotional functioning in the preschool period. There is evidence, starting at age 6 months, that programs based exclusively at education centres may be helpful for children at risk. Some of the effective programs have been particularly "high-powered," involving very low child-to-instructor ratios, but others simply fall into the category of good community day care. However, the quality and content of the programs do matter. When alternative programs are studied using a common evaluation protocol, differences in outcomes are found between programs and by gender between programs.

Intervention Studies in the School Years

The literature on school success following preschool and school-age intervention is divided between those studies that seem to show improvements primarily due to gains in cognitive development and those which seem to suggest that socio-emotional effects may be more durable and may have a longer lasting impact.

In at least five studies, including the Carolina Abecedarian Project (Horacek et al., 1987), there is evidence that gains in cognitive development increased with increasing longevity in the program. For example, there is evidence that Head Start programs in the preschool period are more effective in creating long-term gains in cognitive and socio-emotional outcomes when they were supplemented with primary school follow-throughs.

As children get older, the array of influences on their lives becomes more complex. As children age, the evidence presented on cumulative effects becomes significant. Community characteristics, labour market forces, and peer relationships begin to predominate, as classroom and home take up an ever-shrinking fraction of children's time and their consciousness. This is the time when health and well-being requires broad social and economic change - not just targeted interventions designed to improve the individual life course.

5. Targeted or Universal Interventions

The weight of evidence reinforces the importance of putting in place effective interventions to modify or change life trajectories. However, findings also point out the myriad of problems which can occur if targeted programs are initiated in the absence of universal approaches within communities that promote full participation for each child. Some findings on the problems associated with targeted programs include:

The procedure of targeting individuals brings with it the possibility of labelling and stigmatization. A challenge for the targeted approach is to identify accurately the population at risk in such a way that labelling and stigmatization are minimized.

The reliability and usefulness of the screening procedure:

• The procedure itself may be costly.

• The refusal rate of participation in the collection of screening data may be highest among those at greatest risk for future disorder.

• There is a boundary or threshold issue. At some point, a threshold is set based on the screening data so that those above it screen positive and those below it do not. The differences of risk of those who are targeted and those who are not may be slight.

• There may be an inability to target accurately.

Another important disadvantage of an exclusive focus on the targeted approach is that it has limited potential both for individuals and for populations. There are three reasons for this:

1. The ability to predict future behaviours is currently very weak.

2. A large number of people at small risk give rise to more cases of a disease or disorder than the small number at high risk. For example, data from the Ontario Child Health Study demonstrated that economically disadvantaged children account for only 14.5% of the population with psychiatric disorders. On the other hand, children who live in families who are well off financially account for more than half (59%) of the children with psychiatric disorders.

The risk for such disorders is much lower in these children than in the poor population, but their large numbers mean that their contribution to the population of disordered children is far greater than that of poor children.

3. A targeted approach tends to ignore the community-wide social context as a mechanism of change. It centres on detecting risk factors that distinguish the high-risk group from the low-risk group. It never considers as a focus for interventions those causal risk or protective factors that apply to the whole community and are responsible for the disadvantaged status of the children as a group in that community, nor does it consider the role of community-wide protective factors (see chart below of well-run day care centres).

4. Focussing on changing behaviour of a high-risk subgroup will be difficult if the behaviour at issue is widespread in the population. It is difficult to change one's behaviour when everyone around you is behaving in much the same way. For example, in targeted approaches with adolescents, sometimes youths become worse with the intervention because youths with behavioural problems interact and build peer relationships that promote deviant behaviour.

Conclusion

The above discussion provides some reflections flowing from Developmental Health and the Wealth of Nations on how Canada can plan interventions to improve population health. However, further synthesis and research on how to provide the most effective mix of universal and targeted interventions to maintain or improve population health in Canada is clearly needed.

Appendix A