The Importance of Asymmetry

by | Sep 21, 2022

When I give a formal talk on aging at a conference, one of the more interesting attributes about human longevity I mention that tends to shock the audience is the predictability of the survival distribution. My colleague and I have referred to this consistently observed age pattern of death as a “mortality signature” for our species.

While the age-specific risk of death has declined and life expectancy risen in the last 125 years, the age trajectory of death has never changed. The mortality signature for humans is quite distinct; it has unique quantifiable attributes for people of any age; and it is present in a distinct form for almost all sexually reproducing species.

This means that for any national population, from one year to the next – even during the Covid pandemic – the timing of death in the population is highly predictable. However, life settlement populations are not average. On the one hand, they are members of an insured subpopulation, which has been known for some time to carry lower mortality risks relative to average. On the other hand, some people are selling their insurance policy because they’re facing health challenges – which could mean they’re facing a higher risk of death relative to average.

In a future Newsletter I’ll discuss the unique mortality dynamics we discovered in life settlement populations based on our evaluation of a large database of people that sold (or considered selling) their policies through this industry.

Our job as an LE provider is to generate the most well-informed decision possible on whether the individual is likely to be to the right (longer-lived) side of the survival distribution, or on the left (shorter-lived) side with a higher risk of death relative to average?

After working in the various fields that inform aging science for decades prior to the existence of the life settlement industry, my colleagues and I know exactly what to look for in the personal history of an individual to gauge whether they are likely to live longer or shorter than average – and by how much. This requires an assessment of not just the medical records and the documented primary impairments and their etiology, progression, and treatment, but all of the other intermediary factors (both inherited and acquired during the course of life) that influence how age and one or more diseases influence individual survival.

Most of the attributes of individuals we evaluate at Lapetus have predictable and, importantly, quantifiable impacts on survival – and we quantify them in our assessment whenever possible – and provide you with the empirical evidence to support our conclusions.

But on occasion we run into information contained in the medical record suggesting that an individual could live longer or shorter than one of the tails of the survival distribution – even after taking all other impairments and personal attributes into account. While we cannot quantify these “signals” that a longer or shorter life might occur, we do provide our clients with a warning sign of sorts.

The warning sign we provide appears in the form of suggested asymmetry in the survival distribution, which is a new element of our LE reports added at the beginning of this year. How does it work? If the doctor reviewing the files discovers attributes of an individual that could influence the survival outcome in either direction beyond that already identified by the prevailing impairments and personal attributes, and which cannot as yet be quantified, the physician renders a judgment on the potential magnitude of the effect by ticking the box indicating there may be asymmetry in the survival outcome for the patient.

An asymmetrical signal for a shorter life appears in red where the tail of the lower bound of the survival distribution is extended to younger ages (see Figure 1 below). Examples of left tail signals for asymmetry include a particularly high fall risk; lack of adherence to doctor’s orders; a decision by the patient to adopt alternative treatments; the recent death of a spouse; among many others.

Figure 1.

An asymmetrical signal for a longer life appears in blue with the tail of the survival distribution extended to older ages (see Figure 2 below). Examples of right tail signals for asymmetry include a family history of exceptional longevity; fewer than average medications for a person their age; distant history of disease; level of physical activity; current employment status; sexual function; among many others.

Figure 2.

We hope our clients find the addition of asymmetrical signals in our LE assessments a unique and useful tool for evaluating the value of a policy. Lapetus will be adding in additional information in the future as a way to continuously update and enhance our reports.

If readers of this newsletter have suggestions on additional parameters they would find valuable in these reports, please don’t hesitate to get in touch – we’re always receptive to news ways of enhancing our technology.