Abstract
BACKGROUND: An estimated 10-30% of people with COVID-19 experience debilitating long-term symptoms or long covid. Underlying health conditions associated with chronic inflammation may increase the risk of long covid. METHODS: We conducted a systematic review and meta-analysis to examine whether long covid risk was altered by pre-existing asthma or chronic obstructive pulmonary disease (COPD) in adults. We identified studies by searching the PubMed and Embase databases from inception to 13 September 2024. We excluded studies that focused on children or defined long covid only in terms of respiratory symptoms. We used random-effects, restricted maximum likelihood models to analyse data pooled from 51 studies, which included 43 analyses of asthma and 30 analyses of COPD. The risk of bias was assessed using a ROBINS-E table. RESULTS: We found 41% increased odds of long covid with pre-existing asthma (95% CI 1.29 to 1.54); pre-existing COPD was associated with 32% increased odds (95% CI 1.16 to 1.51). Pre-existing asthma, but not COPD, was associated with increased odds of long covid-associated fatigue. We observed heterogeneity in the results of studies of asthma related to hospitalisation status. Potential confounding and inconsistent measurement of exposure and outcome variables were among the identified limitations. CONCLUSIONS: Our findings support the hypothesis that pre-existing asthma and COPD increase the risk of long covid, including chronic fatigue outcomes in patients with asthma. Because COVID-19 targets the respiratory tract, these inflammatory conditions of the lower respiratory tract could provide mechanistic clues to a common pathway for the development of long-term sequelae in patients with long covid.