Before their time - Would most covid-19 victims have died soon, without the virus ? | Graphic detail

“Sacrifice the weak”, urged a sign at a protest against Tennessee’s lockdown on April 20th—though whether the person holding it was trolling the other protesters is unknown. Some claim social distancing is pointless, since covid-19’s elderly victims would soon have died of other causes. In Britain many pundits have said that two-thirds of the country’s dead were already within a year of passing away. They cite an estimate made in March by Neil Ferguson, an epidemiologist at Imperial College London who advises the government.

Mr Ferguson notes that two-thirds was the upper bound of his estimate, and that the real fraction could be much lower. He says it is “very hard” to measure how ill covid-19’s victims were before catching it, and how long they might have lived otherwise. However, a study by researchers from a group of Scottish universities has attempted to do so. They found that the years of life lost (ylls) for the average Briton or Italian who passed away was probably around 11, meaning that few of covid-19’s victims would have died soon otherwise.

First the authors analysed data for 6,801 Italian victims, grouped by age and sex for confidentiality. About 40% of men were older than 80, as were 60% of women. (The virus has killed fewer women than men, perhaps because they have different immune responses.) The authors excluded the 1% of victims under 50. Then they calculated how much longer these cohorts would normally survive. Life expectancies for old people are surprisingly high, even when they have underlying conditions, because many of the unhealthiest have already passed away. For example, an average Italian 80-year-old will reach 90. The ylls from this method were 11.5 for Italian men and 10.9 for women.

Then the authors accounted for other illnesses the victims had, in case they were unusually frail for their age. For 710 Italians, they could see how many had a specific long-term condition, such as hypertension or cancer. The authors used a smaller Scottish sample to estimate how often each combination of diseases occurs among covid-19 victims. Finally, they analysed data for 850,000 Welsh people, to predict how long somebody with a given age and set of conditions would normally live.

Strikingly, the study shows that in this hybrid European model, people killed by covid-19 had only slightly higher rates of underlying illness than everyone else their age. When the authors adjusted for pre-existing conditions and then simulated deaths using normal Italian life expectancies, the ylls dropped just a little, to 11.1 for men and 10.2 for women. (They were slightly lower for Britons.) Fully 20% of the dead were reasonably healthy people in their 50s and 60s, who were expected to live for another 25 years on average.

The researchers warn that their data exclude people who died in care homes, who might have been especially sickly. Nor can they account for the severity of underlying illnesses. For example, covid-19 victims might have had particularly acute lung or heart conditions. More complete data could produce a lower estimate of ylls. Mr Ferguson also points out that tallies of all-cause mortality will contain clues. If the pandemic has merely hastened imminent deaths, there should be fewer than usual once covid-19 is under control.

Still, the available evidence suggests that many covid-19 victims were far from death’s door previously, and cut down at least a decade before their time. Allowing the virus to spread freely would sacrifice the strong as well as the weak. ■

Sources: “Covid-19 – exploring the implications of long-term condition type and extent of multimorbidity on years of life lost: a modelling study”, by P Hanlon, F Chadwick, A Shah et al., 2020; Istituto Superiore di Sanità (Italy); SAIL Databank (Wales); Public Health Scotland
This article appeared in the Graphic detail section of the print edition under the headline “Before their time”

▻https://wellcomeopenresearch.org/articles/5-75