Post-covid syndrome in individuals admitted to hospital with covid-19: retrospective cohort study
BMJ 2021; 372 doi: https://doi.org/10.1136/bmj.n693 (Published 31 March 2021) Cite this as: BMJ 2021;372:n693Read our latest coverage of the coronavirus outbreak
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Fresh evidence of the scale and scope of long covid
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Long covid—looking across data, diseases and disciplines

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Dear Editor
COVID-19 is a respiratory infection, although it can be associated with both acute and long term systemic complications. Breathlessness is among the most common symptoms reported in individuals followed up after hospital admission (1), following infection identified in the community (2) and in individuals reporting that they have long-COVID (3).
Consistent with this, in their paper on post-COVID syndrome in individuals admitted to hospital with COVID-19, Ayoubkhani and colleagues report rates of respiratory disease, diabetes, and cardiovascular disease to be significantly raised in patients who had been hospitalised with COVID-19; 770 (95% CI 758 to 783), 127 (122 to 132), and 126 (121 to 131) diagnoses per 1000 person years, respectively (4).
Given this six-fold higher rate of lung problems than the next nearest comparator, it is striking that in illustrating this the BMJ cover image is a “warning sign” that includes cardiovascular disease, multi-organ disease, liver disease and diabetes but omits respiratory involvement. The respiratory data are also omitted from the key bar chart in the paper. Of note, the authors regret that they “did not capture symptoms such as fatigue, disturbances in taste and smell, and anxiety, widely reported in post-COVID syndrome”, but not breathlessness.
People with lung disease and those looking after them are accustomed to the relative neglect these conditions receive compared to the burden they cause (5), but erasing lung disease and the experience of breathlessness from post-COVID starts to look like Hamlet without the Prince.
1. Hopkinson NS, Jenkins G, Hart N. COVID-19 and what comes after? Thorax. 2021;76(4):324-5.
2. Stavem K, Ghanima W, Olsen MK, Gilboe HM, Einvik G. Persistent symptoms 1.5–6 months after COVID-19 in non-hospitalised subjects: a population-based cohort study. Thorax. 2021;76(4):405-7.
3. Buttery SC, Philip KE, Williams P, Fallas A, West B, Cumella A, et al. Patient symptoms and experience following COVID-19: results from a UK wide survey. medRxiv. 2021:2021.04.15.21255348.
4. Ayoubkhani D, Khunti K, Nafilyan V, Maddox T, Humberstone B, Diamond I, et al. Post-covid syndrome in individuals admitted to hospital with covid-19: retrospective cohort study. BMJ. 2021;372:n693.
5. British Lung Foundation. The Battle for Breath - The impact of lung disease in the UK. 2016.
Competing interests: No competing interests
Dear Editor
I read with great interest your study on post-covid syndrome. The authors look at a population discharged before 1st of August 2021. The first documented UK case of COVID 19 was in late January 2020, giving a 6 months window in which early diagnosis of respiratory disease was made for analysis. Given that we know, that in some reports at least, lung function in SARS survivors returns to near-normal levels between 6 month and 1 year, do the authors think it may be too early to make accurate estimates of post COVID-19 respiratory disease?
Competing interests: No competing interests
Dear Editor,
Yet again, the BMJ fails to observe parity. An article discussing long Covid fails to mention mental health, even indirectly. My last similar response was to a paper on pollution. Is the brain not an organ of the body?
At least the accompanying commentary mentions neurological problems and cognitive dysfunction. The practical importance of this is the need for long Covid clinics, insofar as they exist, to include mental health professionals, such as Psychiatrists and Psychologists, if any are available. Otherwise, mental health problems following Covid will be under-recognised and under-treated.
Competing interests: No competing interests
Dear Editor,
In answer to Dr Anand's question, I am not certain that the systemic effects of Covid-19 are due to systemic infection. The systemic cytokine storm can be generated from a locally contained insult (in much the same way as anaphylaxis occurs too rapidly to be attributable to systemic conduction of the toxin). I am not convinced that previous exposure that sensitised the immune system would predispose to the development of a second "attack" of Covid-19 (ie a cytokine storm) should a previous sufferer be reinfected with SARS-C0V-2; to my knowledge there is no evidence that that has ever occurred. Someone on the front line might be more able to produce something.
Competing interests: No competing interests
Dear Editor
That Covid is a systemic infection is , I hope, universally accepted.
But we ought to consider the possibility, indeed probability, that bits and pieces of the pernicious RNA might sensitise the body and a fresh invasion, be it another vaccine or a fresh infection, might lead to a hyperimmune reaction.
Would Dr Bamji and other experts care to consider this?
Competing interests: Have had two jabs of Astra Zeneca
Dear Editor,
Given that it is now clear that Covid-19 is a systemic condition caused by a hyperimmune reaction to the SARS-CoV-2 virus, it is unsurprising that post-Covid multi-organ disease is observed - particularly myocardial damage, vascular phenomena such as stroke, peripheral thrombosis and cardiac infarction. These are all features of acute severe infection, and lasting damage is hardly unexpected.
What would be interesting, however, would be to compare a cohort of patients with Covid-19 who were or were not treated with steroids and anti-interleukin compounds such as tocilizumab. My suspicion is that the treated cohort would have a much lower incidence of multi-system disease, as the acute cause would have been blocked. I hope the authors might consider such a study.
Competing interests: No competing interests
Dear Editor
Vulnerabilities to Covid include many problems of Western diet and lifestyle, including metabolic syndrome, non-alcoholic fatty liver disease, and poor cardiovascular fitness due to too little exercise. This paper demonstrates that these problems are worsened, or initiated, by having Covid.
Much of this could be explained by accelerated ageing due to Covid infection, and I would suggest we look at measures of ageing in sufferers, including tests such as telomere length. Such tests might contribute to our understanding of 'Long Covid'.
Competing interests: No competing interests
Re: Post-covid syndrome in individuals admitted to hospital with covid-19: retrospective cohort study
Dear Editor
We write concerning the Original Research paper BMJ 2021;372:n693
Given the nature of the control group, and the fact (noted by the authors) that many diagnoses may have been delayed last year, we wonder whether much of the apparent increase in new diagnoses post-hospitalization could have been due to confounding from the known increased risk for severe COVID-19 conferred by the conditions studied. In addition, again as the authors have already observed, patients who have recently been hospitalized with COVID-19 will certainly be under greater scrutiny than the chosen controls, especially if those controls have not (yet) had cause to present to medical attention.
For both these reasons, we would concur with the observation of Dr. Boubriak that it may be a little early to present the data, especially using the cited control group, as evidence for COVID-19 predisposing to these chronic diseases. Might it not be that the individuals in the study population were already pre-diabetic etc, and were just brought to medical attention by their acute infection?
This would, of course, not change the conclusion that ‘Long COVID’ or 'Post-Viral Syndrome, COVID-19' clinics should foster multi-specialty working. It would seem to be very much in the interests of all patients (not just those who have suffered this particular infection), and is in fact what General Medical Practitioners, Care of the Elderly specialists, and the dying breed of General Physicians have been doing for years.
Competing interests: No competing interests