• To what extent is health care responsible for our longer lives?

    I pointed out in one of my “It’s been a great century” posts that not all of the reduction in cardiovascular disease specific mortality is due to medical interventions. My other “It’s been a great century” post focused on great strides in public health, which deserves much of the credit for our longer lives.

    It’s famously hard to deduce exactly how much credit to give public health and how much medical care, even for a specific disease. In a year 2000 NEJM paper by Hu et al. the authors estimate that between the early 1980s and the early 1990s,

    the reduction in smoking explained a 13 percent decline in the incidence of coronary disease; improvement in diet explained a 16 percent decline; and increase in postmenopausal hormone use explained a 9 percent decline. On the other hand, the increase in body-mass index explained an 8 percent increase in the incidence of coronary disease.

    However, they also write, correctly, that a limitation of their results is that they

    do not imply that other factors, such as levels of blood pressure and serum cholesterol, are unimportant or do not contribute to this decline, because the effects of diet and lifestyle are partially mediated by their effects on blood pressure and serum cholesterol. […] In the Framingham Study, the increasing use of antihypertensive medication from 1950 to 1989 was associated with a downward trend in the prevalence of hypertension and a concomitant decline in left ventricular hypertrophy.

    David Cutler, Allison Rosen, and Sandeep Vijan (NEJM, 2006) split the difference right down the middle: 50% of declines in mortality due to medical care, 50% due to other factors. They cite studies to back this up. I have not read them yet.

    Analyses aggregated from treatments clearly shown to be medically effective suggest that at least half the life-expectancy gains since 1950 are due to medical advances.[11-13] About 90 percent of the gains in life expectancy are attributable to improvements in the rates of death in infancy and the rates of death from cardiovascular disease. Prevailing estimates suggest that at least half the reduction in these rates are due to medical care.[4,14-23] We therefore assumed in our base case that 50 percent of the total gains in life expectancy were due to medical care. […]

    This assumption is likely to be reasonable, given our finding that 90 percent of the increases in life expectancy during the past four decades have resulted from reductions in the rate of death from cardiovascular disease and death in infancy. Although reductions in the rate of death from cardiovascular causes are multifactorial, prior research has suggested that at least half the reductions in the rate have resulted from medical advances.[14-17] Among infants, more than half the reduction in the mortality rate between 1960 and 2000 resulted from a reduced rate of neonatal death among lowbirth- weight infants (weighing <2500 g), which is due almost entirely to medical advances.[18,19,21-23]

    About cardiovascular disease in particular, Cutler, Deaton, and Lleras-Muney write in a 2006 Journal of Economics Perspectives article,*

    Since 1960, cardiovascular disease mortality has declined by over 50 percent, and cardiovascular disease mortality reductions account for 70 percent of the seven-year increase in life expectancy between 1960 and 2000. Cutler (2004) matches the results of clinical trials to actual mortality declines, and attributes the bulk of the decline in cardiovascular disease mortality—as much as two-thirds of the reduction— to medical advance. Beyond medical advance, the major factor in reduced cardiovascular disease mortality is the reduction in smoking. Smoking rates in the United States have fallen to half their level at the time of the Surgeon General’s 1964 report on the harms of smoking. Continued public health campaigns against tobacco use have been an important part of this decline.

    If all this supporting evidence is sound and convincing, medical care is holding its own. It’s even worth the price, say Cutler and colleagues.

    According to virtually any commonly cited value of a year of life, we found that if medical care accounts for about half the gains in life expectancy, then the increased spending has, on average, been worth it.

    Loaded with waste, yes, but still worth buying at prevailing prices. Of course if price (or cost) outpaces longevity gains, that won’t be true forever. This ignores gains in quality of life, which further enhances the value per dollar spent.

    * Highly recommended and ungated. More on it in a subsequent post.

    References

    4. Cutler DM. Your money or your life: strong medicine for America’s health care system. Oxford, England: Oxford University Press, 2004.

    11. Bunker JP. The role of medical care in contributing to health improvements within societies. Int J Epidemiol 2001;30: 1260-3.

    12. Bunker JP, Frazier HS, Mosteller F. Improving health: measuring effects of medical care. Milbank Q 1994;72:225-58.

    13. Bunker JP. Medicine matters after all. J R Coll Physicians Lond 1995;29:105-12.

    14. 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.

    15. Capewell S, Morrison CE, McMurray JJ. Contribution of modern cardiovascular treatment and risk factor changes to the decline in coronary heart disease mortality in Scotland between 1975 and 1994.

    16. Heart 1999;81:380-6. Hunink MG, Goldman L, Tosteson AN, 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.

    17. Unal B, Critchley JA, Capewell S. Modelling the decline in coronary heart disease deaths in England and Wales, 1981-2000: comparing contributions from primary prevention and secondary prevention. BMJ 2005;331:614.

    18. Williams RL, Chen PM. Identifying the sources of the recent decline in perinatal mortality rates in California. N Engl J Med 1982;306:207-14.

    19. Richardson DK, Gray JE, Gortmaker SL, Goldmann DA, Pursley DM, McCormick MC. Declining severity adjusted mortality: evidence of improving neonatal intensive care. Pediatrics 1998;102:893-9.

    20. Li G, Shahpar C, Grabowski JG, Baker SP. Secular trends of motor vehicle mortality in the United States, 1910-1994. Accid Anal Prev 2001;33:423-32.

    21. Kliegman RM. Neonatal technology, perinatal survival, social consequences, and the perinatal paradox. Am J Public Health 1995;85:909-13.

    22. Cutler DM, Meara ER. The technology of birth: is it worth it? In: Garber AM, ed. Frontiers in health policy research. Cambridge, Mass.: MIT Press, 2000:33-67.

    23. Lee KS, Paneth N, Gartner LM, Pearlman MA, Gruss L. Neonatal mortality: an analysis of the recent improvement in the United States. Am J Public Health 1980; 70:15-21.

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    • This is a subject that always puzzled me.

      We know of the advances in cardiac care: novel classes of rx, and procedures & stenting, Great.

      However, contrast that with rising rates of DM, obesity, and in particular, known non-adherence rates to medications–the presumed interventions on which the mortality rate improvements are based.

      HTN for one. The actual rates of folks properly identified and treated are less than a third. ANother, see this NEJM citation from late last year. Surprising:
      http://www.nejm.org/doi/full/10.1056/NEJMsa1107913

      Give it away for free, and compliance is still low.

      Regardless, the incongruence is odd. Either current adherence levels to lifestyle and rx, as suboptimal as they are, are doing amazing things–and the gap is wide if we assume the ideal, or. we are missing something (tobacco?).

      Brad

      • We are not missing something as obvious as tobacco. Cutler explicitly looks at it, among other things. But why is this so hard to fathom? Better treatments, even if only applied to half the population, leads to greater longevity. Medical care alone is, as I wrote, roughly half the explanation. Some things get better (less smoking), some worse (more obesity). On balance, longevity has increased. It would, naturally, increase more if there were greater access, adherence, and better lifestyle choices. The glass is half full, but it is still half empty. That’s the nature of progress, isn’t it?

        What’s puzzling?

        • Puzzling may be overkill, more like elusive.

          Its the harm vs benefit offset: even with clinical advances, compliance far from ideal (I would say lousy); and even still with obesity trends tapering, the decades long trend accompanied by rises in HTN, DM very robust. Just looking at the facts, a “victory” would seem far afoot, yet, there it is front and center.

          I used a question mark with tobacco given its decline in use, and contribution as a major risk. Certainly, a huge public health win and one we can bank on for dropping CV M&M; I know its adjusted for, but I am attributing some residual confounding (lifestyle change and exercise perhaps) that might wrap in its web. Its the 800 lb gorilla, so I fall back on it for explanations. Knowing what we know about drugs–again, I mentioned above–50% overly rosy. Its not just identifying disease, its treating it optimally. We are not there. Regardless, in my last sentence above, I noted that the delta may be great, ie, imagine if we did have >80% compliance.

          Brad

          • I still can’t see through you words to what it is, precisely, that seems odd or even elusive. I don’t have any problem assimilating the facts. Are you just saying we could do so much better? I agree with that.

    • I’m not sure how you can discuss this topic without mentioning infectious disease management advances and immunization–certainly for the first 50 of those 100 years.