Researchers have attempted to refine and elucidate the link between health systems and health status in a number of ways – for example, by relating national health status to health system spending or numbers of health professionals per capita.
A number of studies discovered by the literature search attempted to gauge the effect of health systems on the health of national populations by cross-national studies (mainly of developing countries) relating health status to national health spending or numbers of health professionals per capita.
Making such comparisons across national borders is fraught with methodological problems, most significantly the diverse nature of how health systems are organised and the confounding effects of numerous other determinants of health. It is not surprising, then, that the evidence is mixed.
National health spendingMany international studies have not been able to demonstrate a statistically robust link between national health spending and health outcomes. For example, one extensive cross-country study found that considerably less than 1% of the observed differences in infant and under-five mortality between countries could be explained by variation in national health care spending. Instead, the variation could be much better explained by the countries’ income per capita, inequality of income distribution, extent of female education, level of ethnic fragmentation, and predominant religion.15 Nevertheless, as one study concluded:
… researchers’ inability to find a systematic relationship between health care spending and health outcomes should not be considered evidence that such a relationship does not exist.16
This particular study overcame some of the methodological problems of cross-country studies by examining health care spending within one country over a number of years and controlling for a detailed list of confounders including lifestyle factors. It found a small but statistically significant association between reduced health care spending and increased death rates among children less than a year old, specifically that a 10% reduction in health care spending led to an increase in infant mortality of 0.5% for boys and 0.4% for girls.
Density of health professionalsAnother measure used in the literature to investigate the extent to which health systems impact on health has been the density of health professionals, that is the number of doctors, nurse and providers serving a given number of people in a population. Top of page
Here too, however, the evidence is not clear cut. In some cases there is, as we would expect, a positive association between a higher density of health professionals and better health; in others no statistically significant association has been found.17
Others have even found an alarming negative correlation: that the number of doctors in an area is associated with high mortality rates even when income is controlled for (the so-called ‘doctor-death correlation’). Fortunately, this is assumed to be a construct of data and statistical analysis rather than a ‘real’ association linked by cause and effect; a recent paper proposes an interesting explanation for this effect in the United States and Japan based on migration and / or social exclusion and racism.18
However, the most comprehensive and methodologically sound attempt to unravel this issue looks at a large number of (mainly) developing countries, and finds that doctors per capita are associated significantly with lower maternal mortality rates, lower infant mortality rates and lower under-5s mortality rates – with the greatest effect on maternal mortality rates.19 However, this study failed to find a significant association between nurse density and the above measures, a result that has been duplicated in other studies.20 Once again, this problem of the ‘invisibility’ of nurses is held to be a construct of limited data, and cannot be taken to mean that nurses are irrelevant to the delivery of health care.
Avoidable mortalityIf national health spending and numbers of health professionals provide only mixed evidence of the effect of health systems, fortunately the concept of ‘avoidable mortality’ provides more robust evidence about the ability of health care systems – and primary health care in particular – to influence the health of populations.
The concept of avoidable mortality had its origin over thirty years ago in the work of the United States Working Group on Preventable and Manageable Diseases chaired by Dr David Rutstein. Primarily concerned with improving the quality of health care through an analysis of ‘unnecessary, untimely deaths’, the group proposed a list of conditions from which death should not occur if proper health care was available.
These conditions were those where mortality could be avoided through the actions of the health system in its broadest sense, including through medical personnel and institutions, governments, other agencies and even the individual themselves. Physicians were seen as having a crucial role, not just in providing direct medical care, but also indirectly through advocacy and leadership on health issues and as a conduit of health information to the community.22Top of page
During the 1980s the concept – now labelled ‘avoidable mortality’ and widely accepted as meaning those deaths that should not occur in the presence of effective and timely health care – began to be used to analyse the overall effectiveness of health systems.23 However, as the use of the measure spread through a series of national studies, so did the methodological diversity with which it has been applied.
No universally agreed upon list of conditions for which mortality is considered avoidable has been fixed upon, although it has became generally agreed to include such diseases as, tuberculosis, childhood measles, some malignant cancers such as breast cancer and skin cancer, chronic rheumatic heart disease, hypertensive disease, cerebrovascular disease, influenza and pneumonia, maternal death, and a substantial proportion of ischaemic heart disease.24
It is also generally agreed that it includes conditions where mortality is preventable or treatable through primary care, hospital care and public health programs (for example, screening programs or immunisation) be included.25
However, differences remain, even around such major methodological issues as the inclusion of conditions where the avoidance of mortality is essentially a matter of primary prevention – and in particular mortality from lung cancer, liver cirrhosis and from motor vehicle accidents, each with their respectively strong associations with the use of tobacco, alcohol, and road safety. These causes of mortality are generally responsive to public health actions concerned with prevention, rather than to clinical intervention at the individual level. Some studies include these as ‘avoidable’ deaths, others do not, with even different editions of the European Community Atlas of ‘Avoidable Death’ taking different approaches.26Top of page
Recent research has focused on differentiating more clearly between avoidable causes of mortality that are susceptible to currently available health care technologies (often called ‘amenable’ mortality) and avoidable causes of mortality which are susceptible to interventions that prevent the condition or disease from occurring in the first place (often called ’preventable mortality’).27
We will return to these distinctions later; in the meantime, let us turn to the overall evidence about avoidable mortality and what it can tell us about the effect health systems in general might have on the health of populations.
What avoidable mortality tells us about the effect of health systemsThe concept of avoidable mortality has allowed researchers to investigate from a sound base the effect, or lack of effect, that health systems exert on the health of populations.
Most developed countries – with a few exceptions– have been showing a fall in overall mortality rates (due to both avoidable and non-avoidable conditions) over the last few decades. Following McKeown and the now universally accepted theory of the social determinants of health, this fall in the ‘background’ mortality rate can be attributed to rising living standards, better nutrition, improved education, better housing, reduced poverty, increased control over life choices, etc.
To see whether health care also makes a contribution, researchers have looked at the differing changes over time in mortality rates for avoidable and non-avoidable conditions. They assume that if the effectiveness of health care remained constant, mortality from both avoidable and non-avoidable conditions would change at the same ‘background’ rate, as determined primarily by factors external to the health system.
In fact, what researchers find consistently is that mortality from avoidable conditions has been declining at a faster rate than that for non-avoidable conditions. They therefore conclude that health care has contributed to at least part of this ‘extra’ decline.29
In particular, Nolte and McKee’s extensive review of empirical studies of avoidable mortality30 finds a consistent pattern whereby mortality from ‘avoidable’ conditions decrease more rapidly than mortality for other causes; they conclude that while McKeown was correct in saying that curative medicine was a minor contributor to improvements in the health of nations up until the mid-twentieth century, since then it has played a more significant role.
In fact they describe a general pattern for the developed world whereby health care in the 1980s had a significant effect on reducing mortality rates from avoidable conditions, mainly through reductions in infant mortality, though to a lesser extent in middle-aged mortality. (Interestingly, by the 1990s the reduction in mortality due to the effects of health were declining in importance, largely due to the fact that infant mortality had already been reduced to very low rates).31Top of page
Scale of the effect of health systemsA number of methodological problems make generalising about the scale of the effect of health systems difficult, in particular the lack of comparability between studies due to their focus on different countries over different periods. There are also diverse definitions of ‘avoidable’ / ‘amenable’ conditions, although generally studies use ‘amenable’ mortality as a measure, that is including those avoidable conditions susceptible to secondary and tertiary intervention, but excluding those conditions susceptible only to ‘primary prevention’ measures such as healthy public policy which lie outside the direct control of the health system.
It is also important to note that low socioeconomic status (including poverty and lack of access to employment) have, not unexpectedly, a strong association with higher levels of avoidable mortality.32
Despite these limitations, some authors have been prepared to conclude that clinical services (including preventive services as well as treatment) can be credited with approximately five of the thirty years of increase in life expectancy in the western world since 1950.33
More cautious approaches note the consistently greater decline in avoidable mortality compared to non-avoidable mortality, and are only prepared to conclude that at least part of this decline is due to improvements in health care.34
Studies of avoidable mortality conclude that, notwithstanding the powerful effects of the broader social determinants of health and socioeconomic factors in particular, health systems do have a significant effect on the health of populations.
Avoidable Mortality in AustraliaWhile this approach has been common in overseas analyses, particularly in Europe and the United States for some time, there is comparatively little published literature in Australia using the concept of avoidable mortality.
However, the last few years have seen some studies35 published which have confirmed the same pattern in Australia as that found so consistently overseas. These show that between 1968 and 2001, avoidable death rates fell by around 70% while non-avoidable rates fell by about 34%, allowing the conclusion that:
While the observed declines in avoidable mortality rates may also reflect changes in other factors that influence mortality such as environment and socioeconomic conditions, they are consistent with, and suggestive of, the health care system being an important determinant of health improvements in Australia in recent decades.36Top of page
Also important was the inclusion of avoidable mortality as one of the National Health Sector Performance Indicators (NHSPIs).37 These show that from 1980 to 2001 avoidable mortality declined steadily by a total of 55% for males and 48% for females. In contrast unavoidable mortality rates fell 22% and 17% respectively.
Similar results for the period 1987 to 2001 have also been documented,38 confirming that the health care system is responsible for at least part of this improvement. Importantly – especially given the large effect of social determinants of health on mortality patterns – this latest extensive study also documents a clear gradient in avoidable mortality between socioeconomic groups: those in the most disadvantaged areas socioeconomically speaking had age standardised death rates from avoidable conditions over 60% higher than those in the most advantaged areas.
This suggests not just that health care itself makes a significant difference to health, but also that access to and effectiveness of health care are strongly associated with broader patterns of poverty and disadvantage – a point that has been tellingly made in other publications.39
Recent studies of avoidable mortality within Australia conclude that, consistent with the patterns seen overseas, the health system within this country has contributed significantly to improving population health over the last forty years.
15 Filmer, D. and L. Pritchett (1999). "The impact of public spending on health: does money matter?" Soc Sci Med 49(10): 1309-23.Top of page
16 Cremieux, P. Y., P. Ouellette, et al. (1999). "Health care spending as determinants of health outcomes." Health Econ 8(7): 627-39. p628
17 Anand, S. and T. Barnighausen (2004). "Human resources and health outcomes: cross-country econometric study." Lancet 364(9445): 1603-9.
18 Young, F. W. (2001). "An explanation of the persistent doctor-mortality association." J Epidemiol Community Health 55(2): 80-4. Note that controlling for these factors still did not result in a positive association between doctor numbers and decreases in mortality, a fact which the authors put down to the relative weakness of health care to produce changes in population health compared to structural and economic factors.
19 Anand, S. and T. Barnighausen (2004). "Human resources and health outcomes: cross-country econometric study." Lancet 364(9445): 1603-9.
20 Robinson, J. and H. Wharrad (2000). "Invisible nursing: exploring health outcomes at a global level. Relationships between infant and under-5 mortality rates and the distribution of health professionals, GNP per capita, and female literacy." J Adv Nurs 32(1): 28-40, Robinson, J. J. and H. Wharrad (2001). "The relationship between attendance at birth and maternal mortality rates: an exploration of United Nations' data sets including the ratios of physicians and nurses to population, GNP per capita and female literacy." J Adv Nurs 34(4): 445-55.
21 This section owes much to a recent comprehensive review of the concept of avoidable mortality which is essential reading for those wishing to understand of this important concept: Nolte, E. and M. McKee (2004). Does healthcare save lives? Avoidable mortality revisited. London, The Nuffield Trust.
22 Rutstein, D. D., W. Berenberg, et al. (1976). "Measuring the quality of medical care. A clinical method." N Engl J Med 294(11): 582-588.
23 Albert, X., A. Bayo, et al. (1996). "The effectiveness of health systems in influencing avoidable mortality: a study in Valencia, Spain, 1975-90." J Epidemiol Community Health 50(3): 320-5, Holland, W. W. (2003). "Commentary: should we not go further than descriptions of avoidable mortality?" Int J Epidemiol 32(3): 447-8.
24 Nolte, E. and M. McKee (2003). "Measuring the health of nations: analysis of mortality amenable to health care." BMJ 327(7424): 1129.
25 Nolte, E. and M. McKee (2004). Does healthcare save lives? Avoidable mortality revisited. London, The Nuffield Trust.
26 Ibid. p 25-26.
27 Ibid.; for a recent Australian exposition on this point, see 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.
28 For example, in Russia during the 1990s. See Andreev, E. M., E. Nolte, et al. (2003). "The evolving pattern of avoidable mortality in Russia." Int J Epidemiol 32(3): 437-46.
29 Korda, R. and J. Butler (2004). The Impact of Health Care on Mortality: Time Trends in Avoidable Mortality in Australia 1968-2001. Canberra, National Centre for Epidemiology and Population Health, Nolte, E. and M. McKee (2004). Does healthcare save lives? Avoidable mortality revisited. London, The Nuffield Trust.
30 Nolte, E. and M. McKee (2004). Does healthcare save lives? Avoidable mortality revisited. London, The Nuffield Trust. p 48
31 Ibid. p 91 Top of page
32 Ibid. p 36
33 Bunker, J. P., H. S. Frazier, et al. (1995). The role of medical care in determining health: creating an inventory of benefits. Society and Health. B. C. Amick, S. Levine, A. R. Tarlov and D. C. Walsh. New York, Oxford University Press.
34 Nolte, E. and M. McKee (2004). Does healthcare save lives? Avoidable mortality revisited. London, The Nuffield Trust.
35 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; Korda, R. and J. Butler (2004). The Impact of Health Care on Mortality: Time Trends in Avoidable Mortality in Australia 1968-2001. Canberra, National Centre for Epidemiology and Population Health, Korda, R. J. and J. R. Butler (2006). "Effect of healthcare on mortality: trends in avoidable mortality in Australia and comparisons with Western Europe." Public Health 120(2): 95-105.
36 Korda, R. and J. Butler (2004). The Impact of Health Care on Mortality: Time Trends in Avoidable Mortality in Australia 1968-2001. Canberra, National Centre for Epidemiology and Population Health. p 5.
37 National Health Performance Committee (2004). National report on health sector performance indicators 2003. Canberra, Australian Institute of Health and Welfare.
38 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.
39 Korda, R. J. and J. R. Butler (2006). "Effect of healthcare on mortality: trends in avoidable mortality in Australia and comparisons with Western Europe." Public Health 120(2): 95-105, Korda, R. J., J. R. Butler, et al. (2007). "Differential impacts of health care in Australia: trend analysis of socioeconomic inequalities in avoidable mortality." Int J Epidemiol 36(1): 157-65.