Patients with oxygen-dependent chronic respiratory failure (CRF) had increased cumulative incidence of laboratory-confirmed COVID-19 infection compared with the general population during the first 9 months of the pandemic, according to study findings published in Respiratory Medicine.
Researchers assessed the risk of COVID-19 infection in patients with oxygen-dependent CRF in different periods of the pandemic in a population-based analysis of the Swedish COVID-19 Investigation for Future Insights — A Population Epidemiology Approach Using Register Linkage (SCIFI-PEARL) study.
Patients with CRF were at least 18 years of age, received ongoing long-term oxygen therapy (LTOT), and had not been diagnosed with COVID-19 prior to LTOT initiation.
The study period was divided into subperiods based on the dominant virus variants: pre-alpha (January 1, 2020, to December 31, 2020); alpha (January 1, 2021, to March 31, 2021); and delta/omicron (April 1, 2021, to study end in May 31, 2022).
A COVID-19 infection was defined as an initial infection of laboratory-confirmed SARS-CoV-2, and the incidence analysis was repeated in the total Swedish population (aged 18 years of age and older) for comparison in January 1, 2020.
Disease severity was defined as mild (no hospitalization), severe (hospitalized at common ward outside the intensive care unit [ICU]), and critical (admitted to ICU or fatal within 1 month of laboratory confirmation).
The number of participants who had ongoing LTOT and no previous COVID-19 at the beginning of the pre-alpha period was 1771; at the start of the alpha period, 1649; and at the start of the delta/omicron period,1610. Among those in the pre-alpha, alpha, and delta/omicron periods, mean patient ages were 76.1 (9.3) years, 75.1 (9.3) years, and 74.9 (9.32) years, respectively, and a minority of patients were men (35.9%, 36.6%, and 36.1 %, respectively).
The cumulative incidence of any COVID-19 infection was greater in patients with oxygen-dependent CRF vs the general population during the pre-alpha period (6.4% vs 4.9%) compared with the alpha period (2.9% vs 3.8%) and delta/omicron period (7.8% vs 15.5%).
The risk of severe/critical COVID-19 infection in patients with oxygen-dependent CRF was 5.1%, 2.3%, and 4.8% in the pre-alpha, alpha, and delta/omicron periods, respectively, compared with corresponding rates of 0.5%, 0.2%, and 0.5% in the general population. Severe/critical disease was much more common among patients with oxygen-dependent CRF vs the general adult population for all periods (all P <.0001).
Increased age, cardiovascular disease, and renal disease were risk factors for any COVID-19 infection and for severe/critical disease. Hypertension was a risk factor for severe/critical disease.
At the end of the pre-alpha period and alpha period, the 1-year mortality risk after laboratory-confirmed COVID-19 in patients with oxygen-dependent CRF was significantly greater compared with those with oxygen-dependent CRF and no
COVID-19 infection (hazard ratio [HR], 1.79; 95% CI, 1.27-2.53 vs HR, 1.43; 95% CI, 1.03-1.99, respectively).
Limitations include the lack of complete population-based data for other potential confounders such as smoking; lack of assessment of the effects of pre-existing immunity induced by vaccination or an undiagnosed previous COVID-19 infection; and the short study period.
“The most important clinical knowledge from this study is that for patients with oxygen-dependent CRF, treated with LTOT, health strategies at least at later stages of the pandemic managed to keep the incidence of COVID-19 infection similar to or below the general population incidence, although critical disease continued to be more common due to their underlying frailty,” the study authors stated.
Sundh J, Palm A, Ljunggren M, et al. Risk and outcomes of COVID-19 in patients with oxygen-dependent chronic respiratory failure–a national cohort study. Respir Med. Published online August 19, 2023. doi:10.1016/j.rmed.2023.107392