Estimating the Impact of COVID-19 Deaths on Future Mesothelioma Diagnoses

Gnarus experts Dr. Jessica Horewitz and Jorge Sirgo provide an update to a presentation given by Gnarus at the Perrin National Asbestos Conference in San Francisco on September 27, 2021. This update updates the analysis to incorporate updated CDC COVID-19 death data as of January 2, 2022.

Mesothelioma is a rare cancer that is most associated with occupational and environmental exposure to asbestos. Existing and previously adopted forecasts estimate that the incidence of mesothelioma, suggests that annual diagnoses were expected to peak or at least plateau in the last ten to fifteen years. Because of this, the expected path of mesothelioma diagnoses is of great interest to many: companies forecasting future liabilities, asbestos trusts working to ensure there are funds for future claimants, and insurers reserving for the future.  For most defendants and trusts, claims alleging mesothelioma make up at least seventy percent (and sometimes greater than ninety percent) of the indemnity spend on an annual basis and receives the most analytical focus.

Factors that impact the incidence of asbestos-induced mesothelioma includes the size of the exposed population still living, when and where they may have been exposed, the amount and duration of the exposure, and mortality rates. In the last twenty years, updates to forecasts of mesothelioma have focused on duration of exposure and mortality which have resulted in small, incremental changes (mostly upward) on future asbestos-induced mesothelioma. The COVID-19 pandemic, however, has potentially altered the size of the exposed population.

Since 2020 there have been a significant number of deaths attributed to COVID-19. To the extent that the demographic profile of COVID-19 deaths shares some similarities with that of mesothelioma diagnoses, future mesothelioma diagnoses might be impacted by the “lost” cohort of COVID-19 deaths.  We explore the potential impact on mesothelioma diagnoses in this article.

Demographic Similarities

COVID-19 deaths are tracked and reported weekly by the CDC. These deaths are considered “confirmed or presumed” COVID-19. As of January 12, 2022, 834,954 deaths have been attributed to COVID-19 in the US.  Most of these deaths occurred in 2021.  A bit more than half of all the dead were male and more than that were male in each year.

 

The timeline of COVID-19 deaths reveals some additional information.  This graphic shows the timeline of reported deaths split into two panels (female on the left and male on the right).  Both timelines move in concert but show greater numbers for males.  The deaths disaggregated by age cohorts (color-coded in the subtitle) in both panels show that older age cohorts (green, blue, purple) dominate the totals.

The finding is that COVID-19 deaths are mostly male and overwhelmingly older individuals. So how does this demographic profile compare with mesothelioma diagnoses?  We can evaluate this by examining the SEER data published by the National Cancer Institute.

The latest annual Surveillance, Epidemiology, and End Results (“SEER”) Program of the National Cancer Institute data on mesothelioma diagnoses in the United States became available on April 15, 2021. The data reports on rates of mesothelioma diagnoses during 2018, as determined from “cancer registries” from a sampling of hospitals in the United States.  The extrapolated number of mesothelioma diagnoses in the US is approximately 2,800.  About 1,900 of these are male diagnoses and about 930 are female diagnoses. This graphic below shows the rates of mesothelioma by sex (female in red and male in blue) and by age cohort.  The error bars in black indicate the confidence intervals for each rate.  The data here show that meso rates are considerably greater for older age cohorts (also, they’re essentially zero at less than 20 or so) and are much greater for male at the older age cohorts.

There are some demonstrable similarities between deaths attributed to COVID-19 and mesothelioma diagnoses.  The rates are both concentrated among older individuals.  In addition, the rates are much greater among male individuals (although the difference is greater for mesothelioma diagnoses).  These similarities suggest that the cohort of deaths attributed to COVID-19 may impact the population that more likely to be diagnosed with mesothelioma.  It can be argued that a portion of these deaths had they not occurred might have become meso diagnoses at some point in the future.

Methodological Approach

To estimate the potential change (reduction) in future mesothelioma diagnoses that could result from deaths attributed to COVID-19 we align COVID-19 related deaths with the population that give rise to mesothelioma diagnoses.

Our approach assumes the population of COVID-19 deaths will age in a world “but for” the pandemic to estimate the number of “lost” mesothelioma diagnoses.  First, the population of COVID-19 deaths by year of death, sex, and age cohort from the CDC is disaggregated into age cohorts into single ages using Census data. The mortality information published by the SSA (by sex, age, and year) is then used to estimate the portion of the COVID-19 dead population that would have remained alive in each year 2020 through 2050.  Finally, the mesothelioma diagnosis rates by age and sex from SEER are used to estimate how many of the remaining population might have been diagnosed.

Findings

We estimate that approximately 479 fewer mesothelioma diagnoses between 2020 and 2050 because of the deaths attributed to COVID-19 in 2020-2022.  Of these, about 402 are male diagnoses and about 77 are female diagnoses.  The following tables/charts summarize the demographic profile of the estimated “lost” mesothelioma diagnoses.

Given the current levels of mesothelioma diagnoses (approximately 2,800 overall, of which 1,900 are male diagnoses and about 930 are female), the estimated “lost” mesothelioma diagnoses in the initial years (20-30) are relatively small.  With the expectation that mesothelioma diagnoses do begin to decline into the future, the estimated “lost” mesothelioma diagnoses through 2050 appear to be even smaller.

Limitations

This overview analysis is a first pass at quantifying the impact that COVID-19 deaths may have on future mesothelioma diagnoses, and future refinements of this analysis are likely. This analysis is limited by the available data. Most notably, COVID-19 deaths reported by the CDC may understated, and mesothelioma diagnosis rates obtained via SEER may or may not be directly applicable to the population of deaths attributed to COVID-19.

The assumption of “confirmed or presumed” as the underlying cause of death may have some variability, but it’s difficult to gauge the directional impact if any.  In addition, what’s reported by the CDC might not represent the totality of deaths–the number of deaths is likely to increase through 2022 and perhaps after.  Moreover, estimates of mortality directly or indirectly associated with the COVID-19 pandemic suggests the number is much greater.  These include deaths associated with pandemic-related health care that was delayed or deferred as well as an increase in mental health disorders. There are published estimates that suggest the number of COVID-19 deaths is understated by 20% to as much as 58%.

The SEER data is current through 2018 which was released this past April.  We assume the rates apply directly to this population of deaths (by age and sex).  There’s nothing of which we are aware that would suggest this population would be more or less prone to diagnoses, but if there is, then the estimation would change.  In addition, we hold these 2018 rates constant into the future.

This graphic below shows the rates of meso diagnoses over the past 19 years by sex (female on the left and male on the right) and by age cohort (color-coded in the subtitle).  Constant rates for female might be plausible.  For male, constant rates for age cohorts appears to be conservative, especially for the 55-64, 65-74, 75-84 cohorts.  These rates appear to be declining and these are the age cohorts with the greatest rates. If rates were to continue to decline, our estimate of the “lost” meso deaths would decrease.

Mortality rates are available through age 119 so we assume 100% mortality at age 120.  We use mortality rates by age and sex (for years 2020-2050) from the 2020 SSA Trustees Report.  These rates were published prior to the pandemic.  This is important because we model mortality in the world “but for” the pandemic.  The 2021 Trustees Report was released this month and it shows some very atypical changes to mortality.

This graphic below shows the year-to-year percentage change in mortality rates by age for males in calendar years 2020, 2021, and 2022.  The grey scale lines show the year-to-year percentage changes for mortality rates in the Trustees Reports from 2015 through 2020, and the red line is the change in the mortality rates from the 2021 Trustees Report.  As you can see, the percentage change in mortality rates in the COVID-19 era are considerably greater than the typical change.  This change diminishes staring in 2022.

The CDC tabulates COVID-19 deaths into 11 age cohorts.  Since SEER data and mortality data are available at single ages, we use the distribution from Census of single ages (by sex) to disaggregate.  In addition, the maximum age listed by Census is 100, so the age cohort “85+” extends to 100.

We have not included any impact race and ethnicity might have on our estimates.  First, race is not captured in the SSA mortality data, so that is a potential limitation.  Second, given the relative rarity of meso, splitting the SEER data by sex, age, and race would thin the data too much and result in many “zero” rates.  What the COVID-19 data show is that the distribution of COVID-19 deaths is not representative by race.  Even if race is factored into the approach, the result may not differ.

This graphic below shows the difference between the percent of COVID-19 deaths and the percent of the population by race.  These are adjusted for age differences across the groups.  Any positive disparities (in green) show overrepresentation, and negative (in purple) show underrepresentation.  So Hispanic and Black COVID-19 deaths are overrepresented, and White are underrepresented.

This graphic below shows meso age-adjusted diagnosis rates by sex and race (the horizontal bounded error bars) compared to sex alone (the vertical-colored areas).  The panel on the left is for female and the right is for male.  Both panels show that rates by sex and race are not statistically different to rates by sex alone (aside from Asian).  Not factoring race has a slight overestimating impact because this diagnosis rate is greater than the Hispanic and Black rates would otherwise be (the two groups that are overrepresented in the COVID-19 dead population).

COVID-19 has impacted just about all facets of life over the past almost-two years. It makes sense that the expected number of mesothelioma diagnoses from all causes will change due to the reduction in population caused by the pandemic. The extent to which this becomes a material change in asbestos forecasting is still unknown, but this first pass at estimating the impact of COVID-19 on expected future mesothelioma deaths suggests worthy of continued analysis.

For more information, or if you have any questions about this analysis, please contact Dr. Jessica Horewitz or Jorge Sirgo.