key: cord-0889875-gzzcehof
authors: Calverley, Peter M.A.
title: COPD in the time of COVID-19
date: 2021-04-15
journal: EClinicalMedicine
DOI: 10.1016/j.eclinm.2021.100832
sha: 039bb5811e4858b4a1be1a617ec5aa22395f952c
doc_id: 889875
cord_uid: gzzcehof

nan

The emergence of a novel coronavirus in Wuhan, China in late 2019 has transformed the world and our medical practice. In a remarkable testament to the effectiveness of modern medicine, clinical and basic scientists have developed effective treatment approaches and vaccines within 12 months of the pandemic beginning [1, 2] . The management of infectious disease relies heavily on non-pharmacological measures and good public health advice must be based on an accurate appreciation of who is at risk of contracting the disease. As SARS-CoV-2 infections swept beyond the borders of China clinicians and epidemiologists published numerous papers reporting the principal risk factors for illness À age, male gender, ethnicity and pre-existing illness [3] .

Before the pandemic began chronic obstructive pulmonary disease (COPD) was seen as one of the major causes of global morbidity and mortality [4] . The reduction in ventilatory reserve that characterizes this illness and the propensity to exacerbate when contracting common respiratory viral infections pointed to COPD patients as a major risk group for SARS-CoV-2 infection. Initial data from China tended to support this view but the findings were not clear cut, reflecting the variety of study designs and sample sizes reported. A more international overview of this topic was needed and in a recent publication in EClinicalMedicine Firoozeh Gerayeli and colleagues from a research group in Vancouver with a longstanding interest in COPD have met this need [5] .

These workers identified 59 published studies reporting data about patients with COPD and COVID-19 outcomes. These papers were quite heterogeneous as might be expected given the short timescale for data collection and most were case series where the diagnosis of COPD was extracted from the medical records rather than being confirmed by spirometry. Data came from 16 different countries with the USA and China contributing most reports. Study size varied from 32 patients to over 300.000 recorded in the Mexico national registry. A diagnosis of COPD was associated with a more than fourfold greater chance of hospitalisation, a significant increase in the risk of ICU admission and an almost two and half times greater risk of dying compared to those without this diagnosis. Meta-regression analysis suggested that male sex and especially older age explained these associations to varying degrees within the different outcomes. Somewhat perplexingly the higher the mean age of study participants, the less was the risk of adverse outcomes which may reflect health care behaviors rather than biology.

It is easy to sit in an ivory tower and criticize data like these. Only 4 studies, all in China, set out with the intention of studying the relationship of COPD and COVID-19. The lack of spirometry or data about how COPD impacted the individual makes it hard to understand the relationship between disease severity and adverse outcomes. As the authors note, patient-level data about age, sex and important variables like ethnicity and obesity incorporated in risk-prediction models for COVID-19 outcomes [6] was not available. This is relevant as COPD is a disease of older people which is diagnosed more often in men than women in countries like China and Mexico which contributed substantially to this analysis. Hence the magnitude of risk attributable solely to COPD may be over-estimated. There are always concerns of multiple reports from the same dataset leading to participants being double counted but the Canadian group went to considerable lengths to avoid this problem.

This new meta-analysis was designed to look at the outcome of patients with a COPD diagnosis who developed clinical and/or PCR confirmed SARS-CoV-2 infection. It cannot address whether COPD patients are more likely to contract this infection in the first place. Rather surprisingly patients with a confirmed diagnosis of asthma are not at increased risk of worse outcomes or of contracting COVID-19 infection [7] . There are now data from the UK that suggest that the same is true for COPD patients [8] . While this finding may have a biological basis, it seems more likely to reflect behavioral change in those countries who had some warning of the pandemic's development and took action to shield the most vulnerable people.

Good advice has been issued by the GOLD group on the risks of developing infection with COVID-19 and its appropriate treatment [9] . The present analysis adds to this by emphasizing the need for prevention given the poor outcomes when COVID-19 develops in COPD patients. Perhaps the most remarkable fact about this metaanalysis is that within 15 months of a new viral infection being identified so much data has been published that it can meaningfully synthesized to inform global public health priorities.

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