People who were hospitalised with Covid-19 and continued to experience symptoms after five months show limited further recovery one year after hospital discharge, according to the latest results of the PHOSP-COVID study.
The study, led by the NIHR Leicester BRC in collaboration with hospitals around the country, including Imperial College Healthcare NHS Trust, also confirmed earlier research that people who were less likely to make a full recovery from Covid-19 were likely to be female, living with obesity and required mechanical ventilation to support their breathing during their hospital stay. At Imperial College Healthcare, the study has also been supported by the NIHR Imperial BRC.
Researchers from 53 institutions and 83 hospitals across the UK assessed 2,230 adults who had been hospitalised with Covid-19. All participants completed a five-month assessment; so far, 807 people have completed both the five-month and 12-month assessments. Recovery was measured using patient-reported data, physical performance and organ function tests. Participant blood samples at the five-month visit were analysed for around 300 substances linked to inflammation and immunity.
They found that one year after hospital discharge, less than 3 in 10 patients reported they felt fully recovered, largely unchanged from 2.5 in 10 at five months. The most common ongoing symptoms were fatigue, muscle pain, physically slowing down, poor sleep and breathlessness. Participants felt their health-related quality of life remained substantially worse one year after hospital discharge, compared to pre-Covid. This suggests the physical and mental health impairments reported in the study are unlikely to be pre-existing conditions.
A cluster analysis, which is a mathematical method to group participants according to similar traits and characteristics, identified four distinct groups based on the severity of physical, mental and cognitive impairments experienced at five months. The number of persistent symptoms was much higher in the ‘very severe’ group compared to the ‘mild’ group. In all of these clusters, there was little improvement in physical and mental health from the five-month to one-year assessments.
The researchers compared the blood profiles across the four clusters. They identified higher levels of substances associated with whole-body inflammation and molecules associated with tissue damage and repair, in participants with very severe long Covid compared to mild. They also found a pattern of substances linked to poor cognition (‘brain fog’) in the cluster of patients reporting symptoms such as ‘brain fog’ or slowed thinking, suggesting possible neuro-inflammation.
Professor Chris Brightling, NIHR senior investigator and professor of respiratory medicine at the University of Leicester, and chief investigator for the PHOSP-COVID study, said: “The PHOSP-COVID study is further evidence of the UK’s ability to combine expertise across both disease area and geography to rapidly gather data to help us understand the longer term implications of long Covid in hospitalised patients with persistent symptoms. Our findings show that people who were hospitalised and went on to develop long-Covid are not getting substantially better a year after they were discharged from hospital. Many patients in our study had not fully recovered at five months and most of these reported little positive change in their health condition at one year.
“When you consider that over half a million people in the UK have been admitted to hospital as a result of Covid-19, we are talking about a sizeable population at risk of persistent ill-health and reduced quality of life.”
NIHR Imperial BRC researcher, Professor Luke Howard, who leads the study at Imperial College Healthcare, said: “It is vital that we understand the long term impact of Covid-19 on our population. This wide-reaching evidence, which has only been possible through national collaboration, can help inform us about the best way to treat patients who are experiencing symptoms long after their initial infection, and ensure we provide the best possible support for their continued recovery.”
Professor Fiona Watt, Executive Chair of the Medical Research Council, which co-funded the study, said: “This new evidence from the PHOSP-COVID study provides us with vital information about the long term effects associated with Covid-19 in patients who were treated in hospital. The information will inform the development of effective ways to help long-Covid patients.”
The consortium acknowledges that there may be self-selection bias in the patients returning for one-year visits, although from the data it appears that there are no clear differences between the patients attending the one-year follow-up and the larger participant population in the wider study including their recovery at five months. Assuming all the participants who had missing data at one year had either not recovered or were fully recovered, the adjusted figures are 2 in 10 or 6 in 10 people recovering from Covid-19 at one year, respectively.
The PHOSP-COVID study is available as a pre-print, which means it is yet to be checked by other scientists.