A third of patients in hospital for two weeks or more with COVID-19 die, with dementia and obesity the underlying health conditions carrying the biggest risk a study has claimed.

The finding comes from a major British study by the Coronavirus Clinical Characterisation Consortium which looked at almost 17,000 people admitted to hospital with the virus.

The research showed that overall a third (33%) of the 6,628 patients who had been admitted at least 14 days before the data was collected had died.

For those in intensive care or high dependency units the mortality rate was 45%, increasing to 53% for those given invasive ventilation.

It found that 53% of patients in hospital for COVID-19 have a pre-existing condition, with chronic heart disease the most common (29%), followed by uncomplicated diabetes, non-asthmatic chronic pulmonary disease, and asthma.


But it also found that the risk of death was 39% higher among patients with dementia, 37% higher in obese patients and 31% higher for heart disease.

This means that, after adjusting for other medical problems such as lung, heart and kidney disease, having a BMI (body mass index) over 30 is a significant factor associated with death from the disease.

The researchers believe the reason for the increased risk could be because obese people have reduced lung function and possibly more inflammation in adipose tissue - the fatty tissue around the internal organs.

:: Listen to the Daily podcast on Apple Podcasts, Google Podcasts, Spotify, Spreaker

This could contribute to a "cytokine storm", the life-threatening over-reaction by the body's immune system that is being seen in many COVID-19 hospital patients.

Image: Two medics study notes while wearing their protective gear at Croydon University Hospital

The rate of hospital admission and death also increased with age.

The research also tracked the most commons symptoms displayed by patients, with cough and fever the most common.

The study also found:

Most of the elderly patients who did not survive were admitted to hospital with symptoms of COVID-19 and " would not have died otherwise "

" The median age of those who died in hospital from COVID-19 in the UK was 80 years, and only 12% of these patients had no pre-existing condition recorded

Of the 16,749 patients included in the study, 7,924 (47%) had no documented reported comorbidity

Of the 6,628 patients who required hospital stays of 14 days or more, almost half (49%) have been discharged, with a further 17% still being treated. 33% died

Seventeen percent of those admitted to hospital required Critical Care - a rate higher than that seen in Italy - and those who have poor outcomes are more often elderly, male and obese

The enhanced severity of the virus in male patients was seen across all age groups

More men (60.2%) than women (39.8%) have been admitted to hospital with COVID-19

Pregnant women are not at an increased risk of death

Professor Calum Semple, who is leading the largest study of coronavirus patients in the UK, said the rate of death was "the same for those admitted to hospital with Ebola".