Long term respiratory complications of covid-19

Different demographics

These findings seem reassuring, but the demographics of patients with severe covid-19 differ from those enrolled in previous longitudinal studies in which few participants were over 45 years and few had comorbidities. Long term outcomes might not be comparable, as many patients admitted to hospital with covid-19 have pre-existing disease and varying degrees of frailty. Risk factors for moderate or severe covid-19 are similar to those of idiopathic pulmonary fibrosis: male gender and older age.9 In addition, coronavirus targets alveolar epithelial cells, and evidence implicates other viruses infecting these cells, such as herpes viruses, in the pathogenesis of pulmonary fibrosis.10 Cellular changes occurring with ageing such as genomic instability, mitochondrial dysfunction, and epigenetic modification might reduce these cells’ ability to respond effectively to viral encounter, triggering pathways that promote both dysregulated repair and fibrosis.11

Since inflammation can lead to fibrosis in several forms of interstitial lung disease, treatment often targets inflammation.12 High dose steroids were given routinely to many patients with SARS, and this might partly explain the limited incidence of fibrosis observed.3,4 The benefit of dexamethasone in severe covid-19 has recently been established, but treatment did not improve acute outcomes among patients with milder disease.13 The longer term implications of steroids in the management of covid-19 have not yet been evaluated but widespread use cannot be recommended due to the substantial morbidity associated with these agents.

Guidelines published by the British Thoracic Society recommend chest radiography three months after discharge for all patients admitted to hospital with covid-19. Those with a history of moderate or severe disease, with persisting symptoms or with radiological abnormalities, require clinical review and further investigation.14 The recently launched post-hospitalisation covid-19 study aims to recruit 10 000 patients in the UK to identify the medical, psychological, and rehabilitation needs of patients admitted to hospital with covid-19 and to provide a comprehensive picture of the longer term effects of infection.15

Most patients with covid-19, however, are managed in the community, and management of their persisting symptoms is less straightforward. Chest radiography might be helpful, and patients can be referred to respiratory clinics for investigation of persisting lung abnormalities and thromboembolic disease. There seems to be a fairly poor correlation between symptoms and objective measures of disease (author’s observation). Fatigue, exercise intolerance, and poor concentration can be particularly problematic. Unfortunately, optimal management remains unclear. An integrated multidisciplinary approach involving doctors, physiotherapists, and psychotherapists is likely to be needed, but many UK centres have yet to establish these services, which will probably have limited resources.

To summarise, persistent respiratory complications following covid-19 may cause substantial population morbidity, and optimal management remains unclear. Prospective studies are under way to evaluate these complications further and to identify people at greatest risk. Meanwhile, a pragmatic approach to primary care management might include first line investigations such chest radiography and oxygen saturation measurements, with referral to secondary care where lung pathology needs investigation. Integrated support from a broader primary care team should be considered for patients with more complex symptoms, including those with disproportionate functional impairment.