COVID-19 in adult patients with pre-existing chronic cardiac, respiratory and metabolic disease: a critical literature review with clinical recommendations

BACKGROUND: A high burden of severe disease and death from the coronavirus disease 2019 (COVID-19) has been consistently observed in older patients, especially those with pre-existing medical co-morbidities. The global pandemic lockdown has isolated many patients with chronic illnesses from their routine medical care. This narrative review article analyses the multitude of issues faced by individuals with underlying medical conditions during the COVID-19 pandemic. METHODS: Sources for this publication were identified through searches of PubMed for articles published between 31st December 2019 and 4th June 2020, using combinations of search terms. Guidelines and updates from reputable agencies were also consulted. Only articles published in the English language were included. RESULTS: The volume of literature on COVID-19 continues to expand, with 17,845 articles indexed on PubMed by 4th June 2020, 130 of which were deemed particularly relevant to the subject matter of this review. Older patients are more likely to progress to severe COVID-19 disease requiring intensive care unit (ICU) admission. Patients with pre-existing cardiovascular disease, especially hypertension and coronary heart disease, are at greatly increased risk of developing severe and fatal COVID-19 disease. A controversial aspect of the management of COVID-19 disease has been the use of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers. Obese COVID-19 patients are more likely to require complex ICU management. Putative mechanisms of increased COVID-19 disease severity in diabetes include hyperglycaemia, altered immune function, sub-optimal glycaemic control during hospitalisation, a pro-thrombotic and pro-inflammatory state. Patients with mental health disorders are particularly vulnerable to social isolation, and this has been compounded by the suspension of non-emergency care in hospitals around the world, making it difficult for patients with chronic mental illness to attend outpatient appointments. CONCLUSIONS: The global pandemic of COVID-19 disease has had a disproportionately negative impact on patients living with chronic medical illness. Future research should be directed at efforts to protect vulnerable patients from possible further waves of COVID-19 and minimising the negative impact of pandemic mitigation strategies on these individuals.