Obesity Associated with Higher Risk of COVID and Long COVID

Introduction

High body mass index (BMI), rather than high blood sugar levels, are associated with excess risks of COVID-19 infection and long COVID, according to a meta-analysis of over 30,000 UK adults from nine large prospective cohort studies.

Main Digest

The findings by Dr. Anika Knuppel from the MRC Unit for Lifelong Health and Ageing, University College London, UK, and colleagues are being presented at this year's European Association for the Study of Diabetes (EASD) Annual Meeting in Stockholm, Sweden (19-23 Sept).

"Early in the pandemic research identified diabetes and obesity as risk factors for becoming severely ill with COVID-19. And we know that many people with type 2 diabetes also carry excess weight. Our early findings support the idea that obesity-related mechanisms may be responsible for the excess risks of COVID-19 associated with diabetes, rather than high blood sugar per se," says Dr. Knuppel.

Previous research showed that people with diabetes and obesity are more likely to become severely ill and die if they catch COVID-19 but are no more likely to contract it. However, the underlying mechanisms, and their role in prolonged post-COVID-19 symptoms (long COVID), remain unclear.

To find out more, researchers looked for associations between a range of clinical characteristics measured before the pandemic-HbA1c (average blood sugar level), self-reported or medication-based diabetes, body mass index (BMI), and waist-to-hip ratio (WHR)-and self-reported COVID-19 infection and long COVID in nine ongoing UK cohort studies [1].

The analyses included the most recent measurements (taken between 2002 and 2019) of HbA1c, weight, height, waist, and hip circumference from each study, as well as information from questionnaires on health and lifestyle.

All eligible participants (maximum 31,252, aged 19-75 years old, 57% female) had data on previous measurements and completed at least one questionnaire during the COVID-19 pandemic (May 2020 to September 2021) covering questions on COVID-19 and where possible, questions on the length of ongoing COVID-19-related symptoms.

Participants reported having COVID-19 based on a positive test or strong suspicion. Long COVID was defined as symptoms that went on or affected functioning for longer than four weeks post-infection and were compared to those reporting symptoms for less than four weeks.

Where possible, associations were adjusted for sex, smoking, ethnicity, income, and education at the time of measurement.

Between May 2020 and September 2021, 5,806 participants reported ever having COVID-19, and 584 reported having long COVID (around 7% of COVID-19 cases with information on symptoms length).

Analysis of data from 31,252 participants in nine studies found higher BMI was associated with greater odds of COVID-19 infection-with the risk 7% higher for each 5kg/m2 increase in BMI. People with overweight (BMI 25-29.9kg/m2) and obesity (30 kg/m2 or greater) had 10% and 16% greater odds of COVID-19 infection, respectively, than healthy weight individuals (less than 25 kg/m2).

Similar results were observed for long COVID (4,243 participants, six studies), with the risk 20% higher for each BMI 5kg/m2 increase. People with overweight and obese had 20% and 36% greater odds of long COVID, respectively. However, both COVID infection and long COVID associations with categories of BMI were not all statistically significant (so we cannot be sure they are not due to chance).

Analysis investigating the association with WHR were inconclusive. Notably, studies focusing on average blood sugar level (HbA1c) and diabetes (15,795 participants and 1,917 for long COVID) revealed no association with COVID-19 or long-COVID. The researchers stress the need for further research to explore the mechanisms underpinning these associations and to reduce the excess risk associated with high BMI.

"Our early findings suggest a link of adiposity with COVID-19 infection and long COVID-19 even after considering socio-demographic factors and smoking. We need to explore further what makes people overweight and obese at risk of worse outcomes and how this relates to severe cases", says Knuppel.

The authors acknowledge that the study was observational and cannot prove that higher BMI increases the risk of COVID-19 infection. They cannot rule out the possibility that other unmeasured factors (e.g., underlying conditions) or missing data may have affected the results. They also point out that COVID-19 was based on suspicion rather than a positive test. Clinical measurements taken before the pandemic could be outdated for some of the included studies. Finally, they note that study participants were healthier than the general population, which may limit the conclusions drawn.

References:

[1] The preliminary analyses included data from up to 9 UK prospective cohort studies:

• The 1970 British Cohort Study (BCS70)
• Born in Bradford (BiB)*
• The English Longitudinal Study of Ageing (ELSA)*
• Generation Scotland (GS)
• The Millennium Cohort Study (MCS)
• The National Child and Development Study (NCDS)
• The MRC National Survey of Health and Development (NSHD)*
• Avon Longitudinal Study of Parents and Children (ALSPAC G1)
• Understanding Society (USoc), the UK Household Longitudinal Study.

*Not included in analyses of long COVID.

The study was funded by Characterisation, determinants, mechanisms, and consequences of the long-term effects of COVID-19: providing the evidence base for health care services (CONVALESCENCE) funded by the National Institute for Health and Care Research.

Attribution/Source(s):

This quality-reviewed publication was selected for publishing by the editors of Disabled World due to its significant relevance to the disability community. Originally authored by Diabetologia, and published on 2022/09/18, the content may have been edited for style, clarity, or brevity. For further details or clarifications, Diabetologia can be contacted at bristol.ac.uk. NOTE: Disabled World does not provide any warranties or endorsements related to this article.

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