Chronic obstructive pulmonary disease (COPD) and smoking are associated with more severe outcomes from coronavirus disease 2019 (COVID-19) infection, according to study results published in Respiratory Medicine suggests.

Canadian researchers performed a systematic review of studies to date that have reported the prevalence of respiratory diseases and/or smoking in patients with COVID-19. In total, 22 studies with a pooled population of 13,184 patients with COVID-19 were included in a meta-analysis.

Patients were considered to have a severe case of COVID-19 if they demonstrated worsening of clinical symptoms, met specific criteria described in current clinical guidelines, or required care in the intensive care unit.

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Compared with nonsevere cases, patients with severe COVID-19 outcomes were older and were more often men (63% vs 51%, respectively). In the pooled analysis, factors associated with severe COVID-19 outcomes included the presence of underlying respiratory diseases (odds ratio [OR] 4.21; 95% CI, 2.9-6.0) as well as current smoking (OR, 1.98; 95% CI, 1.16-3.39) and former smoking (OR, 3.46; 95% CI, 2.46-4.85). According to a separate sensitivity analysis, the presence of underlying COPD was associated with higher odds of severe COVID-19 outcomes (OR, 5.8; 95% CI, 3.9-8.5).

Limitations of this meta-analysis were the inclusion of mostly studies from China as well as the limited information on respiratory diseases and smoking statuses in these studies.

According to the investigators, the findings may assist in “the planning of preventive interventions and could contribute to improvements in the assessment and management of patient risk factors in clinical practice, leading to the mitigation of severe outcomes in patients with COVID-19 infection.”


Sanchez-Ramirez DC, Mackey D. Underlying respiratory diseases, specifically COPD, and smoking are associated with severe COVID-19 outcomes: A systematic review and meta-analysis. Respir Med. Published online July 29, 2020. doi:10.1016/j.rmed.2020.106096