We have now seen that, using the concept of avoidable mortality, the literature demonstrates that notwithstanding the powerful effects of socioeconomic class, poverty, and other social determinants, health care can and does have a significant effect on the health of populations.
We turn now to the key question for this report: is there evidence from the international literature regarding the effectiveness of primary health care in particular in improving population health? We find that there are three relevant sources of information in the literature.
- a major cross-country study on the effect of the strength of primary health systems on health status;
- a number of studies looking at the association of health status with primary health care resources, mainly from the United States and using a variety of health measures;
- examinations of avoidable mortality which have looked in more detail at the concept by attempting to determine the effect of the different levels of health care intervention on avoidable mortality.
Primary health care systems: a cross–country studyComparing the performance of health care systems between countries is beset with methodological difficulties – largely to do with comparability of data and the diverse nature of the health systems themselves – such that demonstrating evidentially valid associations can be frustratingly difficult.
However, a major study by key researchers based at John Hopkins University40, looks at thirteen industrialised countries, including Australia, to determine whether the strength of the primary health care system is related to a country’s overall health status and it’s health care costs.
The analysis begins by rating the strength of primary health care systems of each of the countries against a wide range of variables, relating either to health system policy (for example, financing arrangements, requirements for cost-sharing by patients) or to good primary care practice (for example comprehensiveness, coordination, family-centeredness). The study then aggregates these to come up with an overall classification of whether each country has a low, intermediate, or high strength primary care system. (Australia falls into upper end of the group of countries with intermediate strength primary health care systems).Top of page
According to this study, it appears that the strength of a primary health care system is significantly associated with a number of important health measures, and in particular that:
- stronger primary health care is significantly related to lowered mortality of infants from 1 to 12 months of age;
- stronger primary health care is inversely related (though not significantly) to low birth weight, that is, high levels of primary care are associated with reduced rates of low birth weight;
- weaker primary health care is also associated with poorer results in regard to years of potential life lost; and
- stronger primary health care is associated with lower overall national health care costs.
However, those countries with only intermediate strength primary care outperformed those with high levels of primary care when it came to life expectancy from middle age onward, perhaps because generally the intermediate primary health care group have higher overall health expenditures, leading the authors to conclude that
A certain level of health care expenditure may be required to achieve overall good health levels, even in the presence of strong primary care infrastructures.41
On an international level, stronger primary health care systems at a national level are associated with better health outcomes (especially relating to infant health indicators such as low birth weight and infant mortality from 1 to 12 months of age).
Internationally, stronger primary health care systems at a national level are associated with lower overall national health care costs.
Primary health care resources and healthA number of studies have looked within nations – either geographically or over time or both – to see whether there is an association between presumed primary health care resources and health care outcomes.
The most extensive of these are again associated with the John Hopkins team, and comprise an exhaustive analysis of over 3,000 United States counties from 1985-1995, with rigorous attempts to control for confounding variables.Top of page
These studies42 measure primary health care resources by the number of primary care physicians (specifically doctors in family care, internal medicine and paediatrics) per capita. Obviously this can only be a proxy measure of better access to primary health care, and significantly it does not measure the presence of other primary health care workers – though in this case, the effect should be to underestimate the effect of primary health care. Nor, of course, does it measure other factors that may affect the outcomes from primary health care, such as quality or models of care.
The results of these studies are extensive and sometimes complex, investigating not just associations between primary health care resources and mortality, but also the effect of socioeconomic variables, such as inequality in income, and race. Some of the key results include:
- increased primary care resources are associated with lower mortality rates (with an increase of one doctor per 10,000 population associated with a reduction in the mortality rate of 14.4 deaths per 100,000);43
- increased primary care resources are associated with better child and maternal health (with an increase of one primary care doctor per 10,000 population associated with a 2.5% reduction in the infant mortality rate and a 3.2% reduction in low birth weight;44
- increased primary health care resources are consistently associated with lower rates of mortality from heart disease and cancer;45
- primary health care’s association with lower mortality is consistent over time.46
Throughout, the influence of socioeconomic variables – including income inequality – was powerful; but the influence of primary health resources to address its effects was not negligible, leading the authors to conclude:Top of page
From a policy perspective, improvement in population health is likely to require a multi-pronged approach that addresses sociodemographic determinants of health as well as strengthening primary care.49
This series of studies represents the most comprehensive investigation of the link between the availability of primary health care resources and population health. However, other studies have found a similar relationship both in the United States50 and in Canada.51
It should be noted, however, that some studies have not been able to demonstrate a statistically significant association between increased primary health care resources and reduced mortality. They have instead found that issues such as race, education and unemployment better explained health differences52, or that the risks of urban living outweighs any correlation between health service access and mortality53, or even that it is the model of care that predicts whether there is an effect on mortality (private practice being associated with lowered mortality, public employment of physicians having no such association).54
Nevertheless, the weight of evidence is clearly that increased primary health care resources (measured by numbers of primary care practitioners) has a positive effect on the health of populations.
Evidence from overseas – principally the United States – shows a strong correlation between increased primary health care resources and lower mortality rates, and in particular with better maternal and infant health.
Increased primary health care resources are also shown to be able to offset some of the harmful health effects of socioeconomic disadvantage and inequality.
Primary health care and avoidable mortalityBefore ending this chapter, however, it is worth returning to the concept of avoidable mortality, which may itself provide evidence of the effectiveness or otherwise of primary health care on improving population health.
Recently, there have been attempts to use the concept of avoidable mortality to focus not just on the overall effects a health system might be having on the health of a population, but on which areas of the healthcare system might be having that effect.
For example, a study comparing changes in avoidable mortality in the United States and Canada divided the avoidable mortality conditions into those upon which primary health care and/or public health has the greatest impact (for example, asthma, cervical cancer, hypertension and cerebrovascular disease, tuberculosis and maternal mortality) and those most often treated in hospital (for example, Hodgkin disease, appendicitis, cholecystitis, abdominal hernia, peptic ulcer). They concluded that the greater decline in mortality in Canada from causes amenable to primary health care might be traceable to a greater focus in that country on primary care and / or the provision of free health services at the point of use.55Top of page
More systematic attempts have been made to differentiate ‘avoidable’ causes into those:
- Avoidable through primary interventions (prevention) by reducing the incidence of disease through action on lifestyle factors such as smoking and alcohol consumption or on legal and societal measures such as traffic safety or crime reduction;
- Avoidable through secondary interventions (early detection and management) including through screening programs;
- Avoidable through tertiary intervention (treatment) largely requiring medical / surgical intervention but also including immunisation.56
It is important to recall at this point the diversity of approaches to, and ongoing evolution, of the concept of avoidable mortality. The recent extensive study of avoidable mortality in Australia and New Zealand57 did not disaggregate avoidable mortality in this way as it was felt to be too reliant on expert judgment. As we have noted previously, this is a common area of methodological concern and debate in the many studies that use the concept of avoidable mortality.
Nevertheless, the data using this method in the report on Australia’s National Health System Performance Indicators provides important evidence.58 The graphs on the following page show changes in potentially avoidable deaths in Australia from 1980 to 2001 for each of the groups of conditions for males and females.
Obviously, primary health care has a role across all three types of intervention.
For example, primary health care clearly has an important role in interventions aimed at changing individual behaviour (for example, drinking or smoking) and a role in population level interventions / healthy public policy.
Primary health care clearly has a powerful role in immunisation, and is also important in ensuring successful hospital care through post-treatment monitoring and management.
However, primary health care’s role is particularly important for those conditions where mortality can be avoided through early detection and management, that is secondary intervention. Therefore we can surmise that changes in avoidable mortality which is amenable to secondary prevention gives a strong indication of the effectiveness of primary health care.Top of page
In Australia, the NHSPI data tells us that mortality from conditions susceptible to secondary intervention – that is early detection and management – fell by 57.2% for males and 53.6% for females between 1980 and 2001. This evidence strongly suggests that the primary health care system in Australia has contributed significantly to improvements in health in Australia.
Evidence of reductions in avoidable mortality for conditions susceptible to primary, secondary and tertiary intervention in Australia since 1980 suggest that primary health care has made a significant contribution to improved population health in this country.
40 Starfield, B. and L. Shi (2002). "Policy relevant determinants of health: an international perspective." Health Policy 60(3): 201-218.
41 Ibid. p201
42 Shi, L. and B. Starfield (2001). "The effect of primary care physician supply and income inequality on mortality among blacks and whites in US metropolitan areas." Am J Public Health 91(8): 1246-50, Shi, L., J. Macinko, et al. (2003). "The relationship between primary care, income inequality, and mortality in US States, 1980-1995." J Am Board Fam Pract 16(5): 412-22, Shi, L., J. Macinko, et al. (2004). "Primary care, infant mortality, and low birth weight in the states of the USA." J Epidemiol Community Health 58(5): 374-80, Shi, L., J. Macinko, et al. (2005). "Primary care, social inequalities, and all-cause, heart disease, and cancer mortality in US counties, 1990." Am J Public Health 95(4): 674-80, Shi, L., J. Macinko, et al. (2005). "Primary care, race, and mortality in US states." Social Science & Medicine 61: 65-75.
43 Shi, L., J. Macinko, et al. (2005). "Primary care, race, and mortality in US states." Social Science & Medicine 61: 65-75.
44 Shi, L., J. Macinko, et al. (2004). "Primary care, infant mortality, and low birth weight in the states of the USA." J Epidemiol Community Health 58(5): 374-80.
45 Shi, L., J. Macinko, et al. (2005). "Primary care, social inequalities, and all-cause, heart disease, and cancer mortality in US counties, 1990." Am J Public Health 95(4): 674-80.
46 Shi, L., J. Macinko, et al. (2003). "The relationship between primary care, income inequality, and mortality in US States, 1980-1995." J Am Board Fam Pract 16(5): 412-22.
47 Shi, L., J. Macinko, et al. (2005). "Primary care, race, and mortality in US states." Social Science & Medicine 61: 65-75.
50 Farmer, F. L., C. S. Stokes, et al. (1991). "Poverty, primary care and age-specific mortality." J Rural Health 7(2): 153-69.
51 Cremieux, P. Y., P. Ouellette, et al. (1999). "Health care spending as determinants of health outcomes." Health Econ 8(7): 627-39.
52 Mansfield, C. J., J. L. Wilson, et al. (1999). "Premature mortality in the United States: the roles of geographic area, socioeconomic status, household type, and availability of medical care." Am J Public Health 89(6): 893-8.
53 Suarez-Varela, M. M., A. Llopis Gonzalez, et al. (1996). "Variations in avoidable mortality in relation to health care resources and urbanization level." J Environ Pathol Toxicol Oncol 15(2-4): 149-54.
54 Aakvik, A. and T. H. Holmas (2006). "Access to primary health care and health outcomes: the relationships between GP characteristics and mortality rates." J Health Econ 25(6): 1139-53.
55 Manuel, D. G. and Y. Mao (2002). "Avoidable mortality in the United States and Canada, 1980-1996." Am J Public Health 92(9): 1481-4.
56 Nolte, E. and M. McKee (2004). Does healthcare save lives? Avoidable mortality revisited. London, The Nuffield Trust, Tobias, M. and L. C. Yeh (2007). "How much does health care contribute to health inequality in New Zealand?" Australian and New Zealand Journal of Public Health 31(3): 207-10.
57 Page, A., Tobias, M., Glover, J., Wright, C., Hetzel, D., and Fisher, E. (2006) Australian and New Zealand Atlas of Avoidable Mortality. Adelaide, PHIDU, University of Adelaide
58 National Health Performance Committee (2004). National report on health sector performance indicators 2003. Canberra, Australian Institute of Health and Welfare.
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