Quantifying Causes of Mortality and the Relative Burden of Disease

By Michael J. Young

“Mortis effare ordinem et serva vivos”

(State the facts of the death and serve the living)

It was with this incisive charge that Dr. Mark Flomenbaum concluded his lecture on forensic pathology to my medical school class on the final day of our first-year pathology course.

I was reminded of this teaching moment earlier this week when I came across a study recently published in the journal Neurology which found that the annual mortality rate from Alzheimer’s disease (AD) could be nearly six times greater than has previously been reported by the CDC from information gathered from death certificates.  “Deaths from AD,” the authors conclude, “far exceed the numbers reported by the CDC and may be closer in magnitude to the number of deaths reported for heart disease and cancer.”   Were the facts of death in the underreported cases simply misstated?

The authors of the study suggest that the underreporting of Alzheimer’s disease deaths could be attributable to the multifaceted and slowly-progressing nature of the disease and corresponding confusion among physicians about what to designate as the ‘underlying cause of death’:

“Dementia contributes to death insidiously over the course of years through a cascade of events. Eventually, severe dementia causes complications such as swallowing disorders and malnutrition that can lead to fatal conditions such as pneumonia. These more proximate causes are listed on the death certificate as immediate cause of death, while dementia is often omitted as an underlying cause.

Attempting to identify a single cause of death may not capture the reality of the process of dying for most elderly people because multiple factors may contribute to death in the elderly, some proximate and some distal. The elimination of any one of them may allow the individual to live longer. Just as the field has embraced the concept of mixed dementia, acknowledging that multiple neuropathologies may contribute to the expression of dementia…it may be time to consider the analogous concept of “mixed mortality” to more accurately reflect the contribution of multiple disease processes to dying. This more nuanced view of “cause of death” is needed for an accurate understanding of the contributions of chronic diseases such as AD to death in rapidly aging populations”  (James et al. 4-5).

The authors’ call for a more inclusive and nuanced view of death is compelling.  Current U.S. standards for completing death certificates require physicians to specify a mechanism, manner and cause of death.  The cause of death section is divided into two parts: an immediate (i.e., proximate) cause, defined by the CDC as the “final disease, injury, or complication directly causing the death,” and an underlying cause, defined as “the disease or injury that initiated the chain of events that led directly and inevitably to death.”  The CDC emphasizes repeatedly that “only one cause should be entered on a line.”

While the requirement to list only one cause per line may be administratively convenient, it is unclear whether this requirement is philosophically tenable.  Given the multiplicity of factors that may contribute, directly or indirectly, to dying in any given case, limiting characterizations of causes (proximal or ultimate) to monadic events may encourage oversimplified or distorted reporting of processes that are often far more complicated.

In his paper Causation, Nomic Subsumption, and the Concept of Event (1973), philosopher Jaegwon Kim introduced an influential schema for conceptualizing causation that allows for causal relata to be formulated as conjunctions of events that are dyadic or higher-order in composition.  Kim explains that “we think of an event as a concrete object (or n-tuple of objects)  exemplifying a property (or n-adic relation) at a time. In this sense  of ‘event’, events include states, conditions, and the like, and not  only events narrowly conceived as involving changes.  Events, therefore, turn out to be complexes of objects and properties, and also time points and segments, and they have something like a propositional structure…” (222).  Interestingly, many of the examples Kim uses to illustrate features of his framework are cases that involve death as the effect-event.

While adjudicating longstanding questions in the metaphysics of causation might be regarded, prima facie, as beyond the purview of the CDC, the relevance of these issues to how decision are made, how policies are crafted and how resources are allocated is tremendous.  As this month’s study in Neurology highlights, how policy makers and physicians think about and operationalize the notion of causation matters. Assessments of the comparative burden of disease can only be as reliable as the assumptions and theories upon which reporting tools are built. These findings illuminate important areas where philosophers and physicians can work together to improve the efficiency and efficacy of healthcare systems and public health initiatives.

Indeed, to alleviate suffering and to serve the living, we must first equip ourselves with the knowledge and tools to faithfully state the facts of death.

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