New York, Nov 25 (IANS): Researchers have found that among patients who have obesity and tested positive for Covid-19, a past history of bariatric surgery was significantly linked to a lower risk of hospital and intensive care unit (ICU) admission.

Bariatric surgery is an operation that helps you lose weight by making changes to your digestive system.

In the past months, researchers worldwide have identified obesity as a risk factor for developing a severe form of Covid-19, which may require hospital admission, need for intensive care and use of ventilator support.

Obesity is a complex disease caused by multiple factors that weaken the immune system.

According to the study, published in the journal of Surgery for Obesity and Related Diseases, obesity creates a chronic inflammatory state that causes excessive production of cytokines, which are small proteins involved in the immune response.

"Infection with the coronavirus also triggers the immune system to release cytokines, which may lead to excessive cytokine production that damages organs," said study author Ali Aminian from the Cleveland Clinic in the US.

"That may partly explain the severity of infection in patients with obesity," says Aminian added.

In addition, obesity increases the risk for cardiovascular disease, hypertension, diabetes, kidney disease and blood clot formation.

Those conditions can lead to poor outcomes after an infection with SARS-CoV-2, which is the virus that causes Covid-19. Obesity may also affect the respiratory system.

Many patients with obesity have underlying lung conditions, such as sleep apnea and obesity hypoventilation syndrome, that can worsen the outcomes of Covid-19 pneumonia.

The study provides further evidence of the important link between obesity and poor outcomes from coronavirus infection.

It shows for the first time that substantial weight loss via bariatric surgery may actually reduce the risk from severe illness in these patients.

Looking at 4,365 patients who tested positive for SARS-CoV-2, researchers identified 33 patients who had a prior history of weight-loss surgery.

This matched cohort study of 363 patients showed that sustained weight loss and improvement of diabetes and hypertension in the bariatric surgical group prior to contracting Covid-19 was associated with a much lower rate of hospital and ICU admission.

"Patients after bariatric surgery become significantly healthier and can fight the virus better," the authors noted.