37% of COVID-19 Patients Diagnosed With A Long-COVID Symptom- Oxford study

A retrospective study conducted by the University of Oxford in collaboration with the National Institute for Health Research (NIHR) and the Oxford Health Biomedical Research Centre (BRC) has explored the instance, co-occurrence, and evolution of long-COVID symptoms in a cohort of 270,000 people diagnosed with COVID-19.

According to the study published in PLoS Medicine 37 per cent (or 1 in 3) of Covid patients had at least one long Covid symptom even after three to six months after recovery.

The researchers behind the new study utilized a US-based electronic health record network, TriNetX, to conduct a large-scale study of ~270,000 people that were recovering from COVID-19. Their work aimed to provide answers to four key questions, NIHR Academic Clinical Fellow Dr. Max Taquet, who led the analyses, explained in a press briefing: “Our questions [for this research] were: how common were symptoms of long-COVID? Does age, sex, severity of infection or race affect the incidence of long-COVID symptoms? Do the symptoms co-occur? And how do the rate of the symptoms compare after COVID-19 vs influenza?”

The primary cohort of the study included individuals that had received a confirmed diagnosis of COVID-19 on or after January 20, 2020, and that were still alive by the end of follow-up (December 16, 2020). This cohort was matched to a second cohort of patients that had been diagnosed with influenza in the same time frame, and that had not received a confirmed diagnosis of COVID-19.
Over one third diagnosed with at least one long-COVID symptom

The data show that 37% of the primary study cohort received a diagnosis of at least one long-COVID symptom in the 3–6-month period after the initial COVID-19 diagnosis. The percentage incidence for each of the individual symptoms diagnosed were as follows:

Abnormal breathing – 8%
Abdominal symptoms – 8%
Anxiety/depression – 15%
Chest/throat pain – 6%
Cognitive problems (‘brain fog’) – 4%
Fatigue – 6%
Headache – 5%
Myalgia (muscle pain) – 1.5%
Other pain – 7%
Any of the above features – 37%

Higher rates were seen if the whole 1-180 day period after COVID-19 infection was included.

The study also looked at the same symptoms in people recovering from influenza. Long-COVID symptoms did occur after influenza, but were 1.5 times more common after COVID-19.

What did the researchers do and find?

This research used data from electronic health records of 273,618 patients diagnosed with COVID-19 and estimated the risk of having long-COVID features in the 6 months after a diagnosis of COVID-19. It compared the risk of long-COVID features in different groups within the population and also compared the risk to that after influenza.
The research found that over 1 in 3 patients had one or more features of long-COVID recorded between 3 and 6 months after a diagnosis of COVID-19. This was significantly higher than after influenza.
For 2 in 5 of the patients who had long-COVID features in the 3- to 6-month period, they had no record of any such feature in the previous 3 months.
The risk of long-COVID features was higher in patients who had more severe COVID-19 illness, and slightly higher among females and young adults. White and non-white patients were equally affected.

NIHR Academic Clinical Fellow, Dr Max Taquet, who led the analyses, University of Oxford, said:‘The results confirm that a significant proportion of people, of all ages, can be affected by a range of symptoms and difficulties in the six months after COVID-19 infection. These data complement findings from self-report surveys and show that clinicians are diagnosing patients with these symptoms. We need appropriately configured services to deal with the current and future clinical need.’

Professor Paul Harrison, who headed the study, Department of Psychiatry, University of Oxford, said:‘Research of different kinds is urgently needed to understand why not everyone recovers rapidly and fully from COVID-19. We need to identify the mechanisms underlying the diverse symptoms that can affect survivors. This information will be essential if the long-term health consequences of COVID-19 are to be prevented or treated effectively.

To read the full study, Incidence, co-occurrence, and evolution of long-COVID features: A 6-month retrospective cohort study of 273,618 survivors of COVID-19, published in PLOS Medicine.

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