Persistent pulmonary disease after acute covid-19

Lingering pathology contributes to a wider picture of poor health after hospital discharge. However according to up to one year follow-up the prognosis seems that most patients improve.  What should primary care physicians know about post covid presentations and prognosis at this point in time? 

It has been over a year since the first patients were discharged from UK hospitals following treatment for covid-19. Hospital admission was largely dictated by the requirement for supplementary oxygen and additional respiratory support.1 Acute imaging commonly showed multifocal airspace opacification, and venous thromboembolism was recorded in around a quarter of adults admitted to critical care.2 This led to concern about the long term respiratory consequences of covid-19, particularly interstitial lung disease and pulmonary vascular disease.

Although respiratory disease was diagnosed in 29.6% after discharge, rates of extrapulmonary complications, including diabetes, adverse cardiovascular events, and liver and kidney dysfunction were also increased compared with those in population matched controls, indicating that the effect of covid-19 extends far beyond the lungs.

Interestingly, however, while most patients in these studies had persisting symptoms (particularly fatigue, memory problems, and psychological sequelae), only a minority reported dyspnoea.

The percentage of patients with radiological abnormalities fell from 78% at 3 months to 27% (22/83) by 9 months and remained unchanged at 12 months. Only four patients reported dyspnoea one year after discharge and functionally, patients recovered well with normalisation of six minute walk distance. These findings are reassuring, but wide extrapolation should be avoided: participants had a median age of 60 but had no pulmonary and cardiac comorbidities, had never smoked, and 46% did not require respiratory support during the acute infection.

Pulmonary emboli are common in patients in hospital with covid-19.2 Analysis of healthcare claims in the US also found an increased incidence of venous 13 thromboembolism 200 days after the acute illness

To summarise, studies to date show that persisting respiratory complications do occur and that the severity of infection and prior health status are probably the main determinants of radiological and functional impairment longer term. Interstitial abnormalities do not seem to progress (although evidence is sparse) and improve over time.

Importantly, many studies highlight the extent of non-respiratory physical and psychological symptoms after acute covid-19, and follow-up studies report all-cause mortality exceeding 10% in the six months after discharge. Thus, while persisting lung damage may be substantial for some, for many, morbidity and mortality after covid-19 are influenced most by pre-existing conditions, infection severity, and the extra-pulmonary complications of SARS-CoV-2.



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