New Delhi: A study that looked at 12.6 million (126 lakh) Covid patients in England has concluded that obesity increases the likelihood of dying of Covid across ethnicities — but South Asians are at the greatest risk.
Someone of South Asian ethnicity with a body mass index (BMI) of 27 kg per square metre (kg/m2) has the same chance of dying of Covid-19 as a white person with a BMI of 40 kg/m2, according to the study by researchers at the University of Leicester, published in Nature Communications Wednesday.
However, the researchers also found that having too low a BMI may also carry increased risk. BMI is a measure of obesity that is calculated as a ratio of body weight to height squared. Any value above 25 kg/m2 is classified as obesity.
The study, however, was conducted largely on the outcome of Covid cases before the rollout of vaccines in the UK. The researchers said that future work is needed to investigate how these risk factors interact with post-vaccination infection and mortality risk.
This is the first large-scale population-based study to show the continuous association between BMI and Covid-19 mortality across different ethnic groups on a population level.
Using linked national census data, electronic health records, and mortality data for adults in England from the start of the pandemic (January 2020) to December 2020, the researchers conducted a population-based cohort study of obesity, ethnicity, and Covid-19 mortality.
They analysed deaths in white (30,067, or 0.27 per cent of total deaths among white people), Black (1,208, 0.29 per cent), South Asian (1,831, 0.29 per cent) and other ethnic minority groups (845, 0.18 per cent).
The researchers concluded: “The estimated risk of Covid-19 mortality at a BMI of 40 kg/m2 in white ethnicities was equivalent to the risk observed at a BMI of 30.1 kg/m2, 27.0 kg/m2, and 32.2 kg/m2 in Black, South Asian and other ethnic minority groups, respectively”.
There was no significant difference in risk between Black and other ethnic minority groups, compared to white ethnicities at a low BMI of 20 kg/m2, and only a modestly elevated risk in South Asians.
Too low a BMI also increased mortality risk
The researchers found that while higher BMIs are associated with a higher risk of mortality, having too low a BMI may also come with elevated risks.
“The shape of association between BMI and Covid-19 mortality or hospital admissions was J-shaped, particularly in white and other ethnic minority groups, suggesting that the positive association between BMI and Covid-19 outcomes do not extend to lower levels of BMI where low BMI may also be associated with an elevated risk,” they wrote.
They added that this was consistent with meta-analyses for all-cause mortality, which have reported that the nadir in risk occurs between a BMI of 25 and 30 kg/m2.
“The shape of association in the present study could be explained by the fact that low levels of BMI are associated with malnutrition and higher levels of frailty and sarcopenia, which are in themselves associated with a greater risk of Covid-19,” they wrote.
Sarcopenia is muscle loss associated with old age. The researchers said that their findings suggest that the association between a higher BMI and higher Covid mortality is stronger in younger people.
(Edited by Rohan Manoj)
Source: The Print