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.
[F]or 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.
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.