The Limits of the Medical Model
Several recent articles have brought to mind a dilemma, which I have phrased as the limits of the medical model, that seems to be one of the issues in our national debate about what health care is and/or ought to be. In the first study, Moran and associates published a cost-effectiveness analysis of hypertension treatment. Their paper reports on the costs and benefits of treating hypertension in previously untreated adults between the ages of 45 and 74. As is usual for such studies, the benefit was expressed in terms of “quality-adjusted life years,” or QALY.
Since this is specialized term, a word of translation seems appropriate. I became aware of the concept when I studied formal decision analysis some 25 years ago. A simple definition is that it is a concept which captures both the quantity and the quality of life generated as a result of a medical information. The concept recognizes that medical treatments have burdens associated with them, to the point where if a QALY of zero is death, then survival with treatment might have a negative QALY—a mathematical means of expressing the commonsense notion that there are some things worse than death, such as survival in a persistent vegetative state. Although mathematically simple, calculation of QALY can be less than straightforward, particularly when the disease state is rare, and estimation of the rate of various outcomes is statistically uncertain. On the other hand, for a well-studied condition like hypertension, the expected outcomes are statistically reliable.
Moran and associates’ bottom line conclusion is that consistent application of the 2014 hypertension guidelines in JNC 8, which are somewhat more relaxed than those in JNC 7, would save 13,000 lives and prevent 56,000 cardiac events annually.
These are obviously large numbers, which reflects, in part, the prevalence of hypertension as a cardiovascular risk factor. In traditional cost-benefit analysis, an intervention is considered worthwhile, though, if the cost is less than $50,000 per QALY, and this condition was satisfied.
In simple terms, then, treatment of asymptomatic hypertension has measurable benefits and is cost-effective. Yet data from various surveys continues to show many people with hypertension are undiagnosed, and even when diagnosed, are often untreated. Now there are many reasons for this, but one that was brought to mind rather forcefully was a recent conversation with a new patient. He had been sent to me, because his hypertension was significant and he was having symptoms. He had good health insurance, and was medically sophisticated and socially advantaged. In exploring why he stopped taking his medication for over two years, it turned out the real reason was because taking medications meant he was “sick.” Since he did not feel sick, and at 35 did not want to be sick, he found it difficult to make himself take the medication.
On the other hand, many Americans seem to think taking vitamins is healthy, and does not mean you are “sick.” Consider recent publications, though, about vitamin D therapy. The U. S. Preventives Task Force has just published a systematic review of the literature and concluded that “treatment of vitamin D deficiency in asymptomatic persons might reduce mortality risk in institutionalized elderly persons and risk for falls, but not fractures.” The task force statement issued with this study concludes there is not enough evidence to recommend screening asymptomatic adults for vitamin D deficiency, a conclusion in line with every other position paper published on the subject.
A contrary opinion was published in the same journal by Heaney and Armas. While acknowledging the difficulties with defining normal limits, assay variation, dose-response curves, and other technical issues, their basic argument is that a disease-avoidance approach is not appropriate when considering micro-nutrients. There most interesting (to me) argument was why just treating the condition, like we do with iodine, is not appropriate.
Usually, testing improves patient adherence because it provides patient-specific personally applicable information. General assurances that one probably needs extra vitamin D are not as compelling a motivator as knowing one’s number.
Said another way, the editorialists are arguing for application of the medical model, even when analysis of the available medical evidence does not support their recommendations. Perhaps more importantly, it ignores the fact that large segments of the population seem willing to take vitamins, believing it is “natural.”
Finally, another new article shows “sedentary time” is associated with worse outcomes regardless of how active on was. This paper is another meta-analysis, this time looking at the impact of being inert. Given the heterogeneity of the available studies, they tried to analyze results in terms of “sedentary time,” rather than physical activity, and found a strong negative correlation—the more inert one was, the poorer one’s outcomes. Or as conventional wisdom has it, “use it or lose it.” In an accompanying editorial, Lynch and Owens point out that sedentary time is built into modern life, including time spent at the computer. They cite some international efforts to re-engineer ordinary work processes to encourage less sedentary behavior. They conclude:
Understanding the mechanisms by which sedentary behavior increases risk for disease and the precise amount of sitting that generate risk may enable us to more effectively characterize the most at-risk groups within the population. The potential for innovative approaches to reduce healt risks of too much sitting, particularly primary prevention, is considerable, but such approaches should be based on strong evidence.
One problem we as physicians have is the tendency to think about health and disease only through the lens of the medical model. As these articles demonstrate, while there is power in doing so, it is, by itself, not enough to effect either individual or societal changes sufficiently to improve health or to reduce disease. Maybe we need to figure out how to get people to walk to the drug store to buy their vitamin supplements and introduce an anti-hypertensive agent into the carbonated beverages lining the grocery store shelves.
1 February 2015
 Moran AE, Odden MC, Thanataveerat A, Tzong KY, Rasmussen PW, Guzman D, William L, Bibbins-Domingo K, Coxson PG, Goldman L. Cost-Effective of Hypertension Therapy According to 2014 Guidelines. N Engl J Med 2015;372(5):447-455. doi. 10.1056/NEJMsa1406751.
 Phillips C. What Is A QALY? Accessed 1 February 2015 at www.medicine.ox.ac.uk/bandolier/painres/download/whatis/QALY.pdf.
 LeBlanc ES, Zakher B, Daeges M, Pappas M, Chou R. Screening for Vitamin D Deficiency: A Systematic Review for the U. S. Preventive Services Task Force. Ann Intern Med 2015;162:109-122. doi. 10.7326/M14-1659.
 LeFevre ML for USPSTF. Screening for Vitamin D Deficiency in Adults: U. S. Preventive Services Task Force Recommendation Statement. Ann Intern Med 2015;162:133-140. doi. 10.7326/M14-2450.
 Heaney RP, Armas LAG. Screening for Vitamin D Deficiency: Is the Goal Disease Prevention or Full Nutrient Repletion. Ann Intern Med 2015;162:144-145. doi. 10.7326/M14-2573.
 As an example look at the information on WebMD, which scrupulously avoids taking a position, but has page after page of articles. http://www.webmd.com/vitamins-and-supplements/lifestyle-guide-11/default.htm. Accessed 1 February 2015.
 Biswas A, Oh PI, Faulkner GE, Bajaj RR, Silver MA, Mitchell MS, Alter DS. Sedentary Time and Its Association With Risk for Disease Incidence, Mortality, and Hospitalization in Adults. Ann Intern Med 2015;162:123-132. doi. 10.7326/M14-1651.
 Lynch BM, Owen N. Too Much Sitting and Chronic Disease Risk: Steps to Move the Science Forward. Ann Intern Med 2015;162:146-147. doi. 10.7326/M14-2552.
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