The role of medical care in contributing to health improvements within societies

John P Bunker

Department of Epidemiology and Public Health, University College London Medical School, 1–19 Torrington Place, London WC1E 6BT, UK. E-mail: j.bunker{at}public-health.ucl.ac.uk

In attempting to assess the contributions of medical care to health improvements, the goals of care must first be addressed. The saving of lives in acute life-threatening emergencies is an important such goal, but it represents a very small component of the total medical effort: while lives are saved, the sum of such saving is too small to have a measurable impact on the life expectancy of an entire population. A much larger effort is devoted to preventive or curative measures, and these do have a large and measurable effect on the life expectancy of the population as a whole. An even greater component of medical effort is devoted to improving the quality of life, or more accurately, to preventing or to minimizing the poor quality of life associated with chronic disease: to the relief of pain, disfigurement, and disability.

There are no population-based data to allow a direct estimate of the contributions of medical care to life extension or to the quality of life. In the absence of such data, my colleagues and I have created inventories of the outcome benefits of the preventive or curative care for individual conditions. Based on such an inventory of established life extending outcomes of preventive and curative services for individual conditions, I estimate that about half of the 71/2 years of increased life expectancy since 1950 can be attributed to medical care. I credit an even larger number of years of relief, or partial relief, of poor quality of life to medical care. The data on which the estimates are based are often incomplete, and the estimates are approximations. They are more than speculative and less than precise.

Thomas McKeown's Legacy

With a single major exception, the epidemiology of medical care and its effect on health have received little attention over the years. The exception is McKeown's Role of Medicine, based on cause-specific mortality reports for the century ending in 1971.1 Life expectancy had increased by 23 years during the first half century, but McKeown was able to attribute no more than a year or two to advances in medical care. He presented no data on the harm that medical care might incur, but his conclusion that medical care had contributed little to health was interpreted by many as an attack on medicine, and it was linked by many to Ivan Illich's claim that medicine does more harm than good.2 Illich's Medical Nemesis: The Appropriation of Health, published in 1975, and McKeown's Role of Medicine, published the following year raised questions that have remained largely unanswered to this day.

The implications for public health of McKeown's and Illich's books have been largely ignored or considered irrelevant by clinicians, who are busy taking care of patients one at a time. Basic scientists appear not even to have noticed their existence. The Nobel Laureate and President of Rockefeller University, Joshua Lederberg, wrote that ‘by the 1960's we could celebrate the conquest of polio and the transformation of formerly lethal infections to easy targets for penicillin and other miracle drugs ... greater life expectancy—from 47 years in 1900 to 70 in 1960—can be attributed almost entirely to this mastery of infection ...’.3 The Nobel Laureate and former research director of Burroughs Wellcome, the pharmaceutical company, George Hitchings, claimed that ‘the increase in life expectancy over the last 50 years has been attributed to new medicines’.4 Philip Abelson, a former editor of Science, wrote that ‘pharmaceuticals have been responsible for about half of the improvement in health care during this century’.5

The quarter century following publication of The Role of Medicine has seen an explosion of new treatments, many of which have been shown in clinical trials to result in marked improvements in health. Epidemiological evidence crediting medical care with the extension of life began to appear. The American economist Jack Hadley compared expenditures by the government's Medicare programme with regional death rates and reported that for every 10% increase in expenditure there had been a 1–2% fall in mortality.6 It was reported that while death rates have continued to fall for all ages and almost all diseases, death rates for diseases considered ‘amenable to treatment’ have fallen at much greater rates than have death rates for diseases that do not respond favourably to treatment.7 From the differences in their rates of fall it was estimated that medical care could be credited with an extension in life expectancy of between 5 and 18 years.8

Conflicting data also appeared. Age-adjusted death rates were reported to be greater in countries with greater numbers of doctors, and presumably with more medical care.9 Equally difficult to explain, death rates for diseases amenable to treatment were reported to be greatest in areas with the most medical care resources.10 Efforts to separate the effects of medical care for an entire population from those of other determinants of health have been fraught with similar contradictory evidence. It was in an attempt to overcome these difficulties that my associates and I created an inventory of the outcomes of individual medical and surgical interventions, one at a time.11,12

Life Expectancy

Estimation of months or years of increased life expectancy attributable to the treatment of a particular condition involved a three-step procedure: calculation of increases in life expectancy resulting from a decline in diagnosis-specific death rates, estimation of increases in life expectancy when therapy is provided under optimal conditions, and estimation of how much of the decline in disease-specific death rates could be attributed to medical care when provided in routine practice.

To estimate gains in life expectancy attributable to a specific disease, several approaches were used. Changes in life expectancy could be calculated directly from life-tables for those conditions for which mortality rates are available decade by decade. This was possible for heart disease, cerebrovascular disease and pneumonia using data published by the National Center for Health Statistics in Maryland.13 For many other diseases changes in mortality are reported by the National Center as a single age-adjusted rate, precluding a full life-table estimate. For example, the age-adjusted death rate for pneumonia and influenza fell from 26.2 per 100 000 in 1950 to 13.7 in 1989, a reduction of 12.5 per 100 000. During the same period the age-adjusted death rate for all causes fell from 840.5 per 100 000 to 523.0 per 100 000, a difference of 317.5, and life expectancy rose by 7.1 years. As a first approximation, the fall in death rate for pneumonia and influenza was estimated to have contributed 12.5/317.5 x 7.1 = 0.28 years, or about 3 months. Such a ‘back of the envelope’ approximation when applied to age-adjusted death rates for heart and cerebrovascular disease, as well as for pneumonia and influenza, gave answers within 10% or 20% of those based on a full standard life-table.

Estimation of increase in life expectancy under therapeutic conditions was based, whenever possible, on clinical trials and meta-analyses, or alternatively on observational or case-control studies. The proportion of improvement attributable to medical treatment was estimated from published treatment rates and rates of risks and benefits of those receiving treatment. For example, the death rate for cerebrovascular diseases, primarily stroke, fell more than three-fold from 1950 to 1996, representing approximately 130 000 fewer deaths annually and an increase in life expectancy of a little more than one year. Medical control of hypertension in the US increased markedly during this period, from 10% of individuals with moder-ate or severe elevations of blood pressure to approximately 50%,14 and stroke mortality was reported to fall by 35–40% in randomized clinical trials of anti-hypertensive drugs.15 This would explain as much as 15–20% of the reduction in stroke mortality, with an increase in life expectancy of 21/2–3 months.

Mortality from heart disease in the US fell by more than half between 1950 and 1995, with a resultant increase in life expectancy of approximately 31/2 years, half to two-thirds of which has been attributed to coronary care units, treatment of hypertension, and medical and surgical treatment of coronary artery disease.16,17 The treatment of appendicitis, diabetes, and end-stage kidney disease were estimated each to have contributed a third of a year or more to life expectancy, with lesser contributions from the treatment of many other conditions. All told, clinical services, composed of preventive services as well as therapeutic intervention, we credited with 5 or 51/2 years of the 30 years increase in life expectancy since 1900, and half of the 7 or 71/2 years of increase since 1950.12

Relief of Pain, and of Physical and Mental Dysfunction

In the absence of population-based measures of the impact of medical care on the quality of life, an inventory of estimated years of pain and of physical or mental dysfunction prevented or ameliorated as a result of treatment was similarly constructed.12 Estimates were based on the incidence of the condition, the number of those treated, the average age of individuals suffering the condition, and the expected average years of survival. The treatment of cataracts serves as an example of the application of this heuristic. Five to ten per cent of Americans develop cataracts during a lifetime. There are over a million operations to remove the affected lens or to replace it with a prosthesis in the US each year. For 75–90% of individuals there is restoration or marked improvement in visual acuity.18 Assuming that the life expectancy at the time of surgery is, on average, 5 years, the operation can be credited with 20–40 years of improved quality of life for each 100 members of the population, or 21/2–5 months on average for individuals.

In addition to large numbers of years of symptomatic relief, there are many years of disability that are prevented by therapeutic intervention. For example, the effective treatment or prevention of hypertension contributes to a fall in the subsequent incidence of non-fatal as well as fatal heart attacks and strokes, and to a resultant fall in months and years of poorer physical and mental function. Similarly, if it is possible to prevent dyspepsia of peptic ulcer, or to prevent recurrent biliary colic by removing the gall bladder, the months and years of relief or amelioration can be estimated. The months and years can then be added to create an inventory roughly comparable to the so-called DALY, the number of ‘disability-adjusted life years’. The years of improved physical or mental function, or of prevention or amelioration of pain and suffering, add up to an estimated 500 per 100 individuals, that is, about 5 years on average per individual.12

Iatrogenic Disease, Mortality and Morbidity

Treatment can shorten as well as lengthen life expectancy. This is dramatically evident in surgery and anaesthesia which, however well performed, entail some risk of death and has been used to explain, at least in part, differences in life expectancy between countries. The two-fold greater rates of discretionary surgery in America, relative to England and Wales, that I reported in 197019 could thus be expected to reflect this risk and was estimated to account for a third to a half of the greater life expectancy in England and Wales at that time.20 It was assumed that the rates of emergency and lifesaving or life-extending surgery were essentially the same in each country and that the discrepancy in surgical rates applied primarily to discretionary surgery for non-life-threatening conditions.

Iatrogenic mortality may similarly help to explain the observations by Cochrane and by Carr-Hill and their associates that greater numbers of doctors and medical resources, and presumably more discretionary medical and surgical care, are associated with higher death rates.9,10 Iatrogenic mortality is also reflected in the observation of brief but dramatic decreases in population death rate when doctors strike and surgery for elective (but not emergency) operations are suspended.21

That the magnitude of iatrogenic disease is substantial, in medicine as a whole as well as in surgery, has now been documented in the US. A year 2000 report by the Institute of Medicine in Washington estimates that ‘adverse events’ occurring in the course of treatment, one-third to two-thirds of which could be attributed to medical error, are responsible for between 44 000 and 98 000 deaths annually in America. Approximately half of adverse events, non-fatal as well as fatal, occurred in surgical patients and half were attributed to medication.22 This number of deaths would represent between 2% and 4% of all deaths in America, equivalent to a loss of life expectancy of between 4 months and 8 months. Later in the same year it was claimed that there are 225 000 or more iatrogenic deaths in the US annually.23 This estimate was based on data which may be methodologically flawed.24–26 The estimate also fails to take into account evidence that the incidence of iatrogenic death may have fallen during the years subsequent to those on which the Institute of Medicine report is based.27

In the absence of current and reliable data, I estimate that there may be between 75 000 and 150 000 iatrogenic deaths in the US annually, including those that result from medical error. A substantial number of these deaths, perhaps between a third and a half, will have been imbedded in the observational data on which the analyses reported in the foregoing were based.11,12 Adjusting for this confounding and for the shortened remaining years of life of the elderly patients in whom the preponerance of adverse events occur, I estimate that there is a loss of life expectancy of 6 months or possibly as many as 12 months as a result of iatrogenic deaths occurring during medical and surgical treatment.28

Gains from Medical Care in Context

The gains in life expectancy and quality life that I credit to medical care should be seen in the context of other determinants of health. Compared to the very large gains in life expectancy in the first half century that resulted from improvements in public health, the contribution of medical care is relatively small. With improvements in public health largely complete, medical care is now the major determinant of life expectancy, its impact substantially greater than that of the social environment or lifestyle.

In England and Wales, during the years 1987–1991, there was an estimated 91/2-year difference in life expectancy between men in professional social class I and unskilled labourers in social class V; for women the differential was 61/2 years. These were the extremes and represented a relatively small proportion of the population, approximately 7% professionals and 4% unskilled labourers. For the very much larger numbers of men classified as as non-manual and skilled or partly skilled workers the difference in life expectancy was very much smaller: less than one year difference between skilled manual (class IIIM) and skilled non-manual (class IIIN), and a little more than 11/2 years difference between social class II, ‘managerial and technical/intermediate’, and social class IV, partly skilled, e.g. ‘warehousemen, security guards, machine tool operators’.29 After adjusting for the size of each of the social or occupational groups, the net effect of social class on life expectancy of the whole population is 3 years, of which about a third can be charged against the use of tobacco, and possibly as much as a third against poorer access to and poorer quality of medical care.

The impact of an unhealthy lifestyle is large for the individual but relatively small for the life expectancy of the entire population. The individual who smokes and is perhaps overweight and inactive may lose 7, 8, or more years of life expectancy. With about a quarter of the population smoking, the population as a whole would gain about 11/2 years if every smoker quit. Overweight individuals and those classified as obese would, by returning to normal weight, gain as much as a half and 11/2 years of life expectancy, respectively. With more than half of Britons and Americans overweight and over a fifth obese, their return to normal weight could gain about a half-year of life expectancy spread across the population. The inactive but otherwise healthy individual can, by exercising, increase life expectancy by as much as 12 months. Roughly adjusting for confounding by social class, I estimate that the population would gain 2 or 21/2 years of life expectancy if everyone assumed the lifestyle of the fittest.28

Prospects for Better Health

How then should governments, committed to improving the health of the populations they serve, invest for the future? The provision of medical care, the development of healthier personal habits, and the creation of a more just social environment each hold the potential to improve health. The benefits of medical care that have already been achieved can be estimated with considerable precision and they are substantial. The benefits of a healthier lifestyle have been achieved only to a very limited degree, while inequalities in health have increased and are continuing to do so.

If national policy is to be directed to improvement of the health of the population as a whole and reducing inequalities in health, such policy must take into account the potential and the limitations of each. Increased investment in medical care would make the greatest and most predictable contribution to the reduction of death and to the relief or amelioration of suffering and disability. The gains from increased investment in medical care would begin to be seen almost at once, the benefits of health promotion only as rapidly as the public responds with a healthier lifestyle. Redistribution of wealth and resources for the sole purpose of reducing inequalities in health would be a long-term strategy of uncertain success.

Each strategy can potentially lessen inequalities in health. All deserve urgent consideration, and it is a question of how much to invest in each. The British government, if it hopes to ‘improve the health of everyone, and of the worst off in particular’ must not place its hopes too heavily on lifestyle changes, nor should it expect that social reform, however desirable in the name of social justice, will resolve the problem of inequalities in health. The government's stated commitment to the reduction of the death rate from cancer, coronary heart disease, accidents, and from suicide and trauma is, by contrast, a reasonable and attainable target for medical care.

References

1 McKeown T. The Role of Medicine: Dream, Mirage, or Nemesis? London: Nuffield Provincial Hospitals Trust, 1976.

2 Illich I. Medical Nemesis: The Appropriation of Health. London: Calder and Boyars, 1975.

3 Lederberg J. Medicine's old battle against the bugs isn’t over at all. International Herald Tribune, 26 January, 1996.

4 Hitchings GH. Health care and life expectancy. Science 1993;262:1632.[Medline]

5 Ableson PH. Improvements in health care. Science 1993;260:11.[ISI][Medline]

6 Hadley J. More Medical Care, Better Health? Washington DC: Urban Institute Press, 1982.

7 Charlton J, Velez R. Some international comparisons of mortality amenable to medical intervention. Br Med J 1986;292:295–301.[ISI][Medline]

8 Mackenbach JP. The contribution of medical care to mortality decline: McKeown revisited. J Clin Epidemiology 1996;49:1207–13.[ISI][Medline]

9 Cochrane AL, St Leger AS, Moore F. Health service ‘input’ and mortality ‘output’ in developed countries. J Epidemiol Community Health 1978;32:200–05.[Abstract]

10 Carr-Hill RA, Hardman GF, Russell IT. Variations in avoidable mortality and variations in health care resources. Lancet 1987;i: 789–92.

11 Bunker JP, Frazier HS, Mosteller F. Improving health: measuring the effects of medical care. Milbank Q 1994;72:225–58.[ISI][Medline]

12 Bunker JP. Medicine matters after all. J Roy Coll Physicians 1995; 29:105–12.[ISI]

13 National Center for Health Statistics. Health United States, 1996–97 and Injury Chartbook. Hyattsville, Maryland, 1997.

14 Drizd T, Dannenberg AL, Engel A. Blood pressure levels in persons 18–74 years of age in 1976–80, and trends in blood pressure from 1960–80 in the United States. Vital and Health Statistics Series 11, No. 234. DHHS 86–1684. Washington DC: US Government Printing Office, 1986.

15 Collins R, Peto R, MacMahon S et al. Blood pressure, stroke, and coronary heart disease Part 2, short-term reductions in blood pressure: overview of randomised drug trials in their epidemiological context. Lancet 1990;335:827–38.[ISI][Medline]

16 Goldman L, Cook EF. The decline in ischemic heart disease mortality rates: an analysis of the comparative effects of medical interventions and changes in lifestyle. Ann Intern Med 1984;101:825–36.[ISI][Medline]

17 Hunink MGM, Goldman L, Tosteson ANA et al. The recent decline in mortality from coronary heart disease, 1980–1990: the effect of secular trends in risk factors and treatment. JAMA 1997; 277:535–42.[Abstract]

18 Brenner MH, Curbow B, Javitt JC et al. Vision change and quality of life in the elderly: response to cataract surgery and treatment of other chronic ocular conditions. Arch Ophthalmol 1993;111:680–85.[Abstract]

19 Bunker JP. Surgical manpower: a comparison of operations and surgeons in the United States and in England and Wales. N Engl J Med 1970;282:135–44.[ISI][Medline]

20 Bunker JP, Wennberg JE. Operation rates, mortality statistics and the quality of life. N Engl J Med 1973;289:1249–50.[ISI][Medline]

21 Roemer MI. More data on post-surgical deaths related to the 1976 Los Angeles doctor slowdown. Soc Sci Med 1981;15C:161–63.

22 Kohn LT, Corrigan JM, Donaldson MS (eds). To Err is Human: Building a Safer Health System. Washington DC: National Academy Press, 2000.

23 Starfield B. Is US health really the best in the world? JAMA 2000;284: 483–85.[Free Full Text]

24 Freemont-Smith K. Adverse drug reactions in hospital patients (letter to editor). JAMA 1998;280:1741.[Free Full Text]

25 Kravitz GR. Adverse drug reactions in hospital patients (letter to editor). JAMA 1998;2801:741.

26 Rooney C. Increase in US medication-error deaths (letter to editor). Lancet 1998;351:1656–57.[ISI][Medline]

27 Brennan TA. The Institute of Medicine report on human errors—could it do harm? N Engl J Med 2000;342:1123–25.[Free Full Text]

28 Bunker JP. Medicine Matters After All. London: Nuffield Trust, 2001.

29 Hattersley L. Trends in life expectancy by social class—an update. Health Stat Q 1999;Summer:16–24.