You know the cartoon where Bugs Bunny is driving an old car that suddenly falls apart, every bolt sprung, with the last hubcap rattling in a circle until it comes to rest?

Some people die like that, too. The trouble is there’s not a good name for it.

Is there a single problem that gets the final chain of events going? Or should “old age” under some circumstances be considered an actual cause of death — equal to lung cancer, leukemia and diabetes?

Those questions are becoming increasingly important as more and more people die at very advanced ages without an obvious cause that can be confidently entered on the death certificate.

The difficulty of naming a cause of death in the very old is becoming enough of a problem in the industrialized world that the World Health Organization is likely to address it head-on it in the next year.

“If we can’t find a way of dealing with this, then I think mortality statistics will lose much of their value,” said Lars Age Johansson, who chairs WHO’s Mortality Reference Group and is a biostatistician with Sweden’s National Board of Health and Welfare. “I see this as very, very important.”

Part of the reason it’s important is that mortality statistics are the backbone of public health.

Without knowing how the members of a population die, and at what ages, epidemiologists can only guess how many deaths are potentially preventable. On the other hand, good mortality data can identify overlooked problems and help public health agencies decide where to direct effort and money.

The issue is especially topical because experts from around the world next year will start updating the International Classification of Diseases, medicine’s official list of more than 14,000 diagnoses.

“Each revision of the ICD is the right moment to reconsider this question,” said Gerard Pavillon, a French biostatistician who will co-lead the mortality statistics committee.

Some places began recording all deaths and their causes in the early 1800s. The original ICD, called the International List of Causes of Death, was adopted in 1893. It had 161 headings (with more specific causes falling under some of them). Paradoxically, it was probably easier for a physician to choose a cause of death then than it is now when far more is known about the complicated physiology of dying.

Today, doctors are expected to list both “immediate” and “underlying” causes of death and how long those diseases had been present. They are also asked to list “significant conditions contributing to death” but not causing it directly. But picking the “underlying cause” — which is the most important one — when a patient has several chronic illnesses, such as hypertension, dementia and coronary heart disease, is often difficult.