Approximately 77% of patients who were hospitalized with COVID-19 had normal exercise capacity 1 year after discharge, investigators reported in the European Respiratory Journal.
The prospective study of patients hospitalized for COVID-19 sought to determine their cardiopulmonary exercise capacity at 12 months, assess the change from 3 to 12 months, and compare the results from individuals post-COVID-19 with a matched control group of individuals without COVID-19.
The analysis was a substudy of patients who had a cardiopulmonary exercise test (CPET) at 3 and/or 12 months from a Norwegian study titled “Patient-Reported Outcomes and Lung Function after hospitalization for COVID-19” (PROLUN).
Participants in the main study were aged 18 years and older, with a discharge diagnosis of COVID-19 before June 1, 2020, from 6 hospitals. The patients were invited for follow-up visits at 3 and 12 months after discharge. Stepwise incremental treadmill exercise was used for the CPET.
Matched control individuals were recruited from the HUNT4 HOPE cohort of the Norwegian population-based Trøndelag Health study, in which CPET and echocardiography were conducted in 2461 participants between 2017 and 2019.
The main outcome was peak oxygen uptake (VO2peak). Exercise intolerance was defined as VO2peak less than 80% predicted.
A total of 177 patients and 207 controls were included in the analysis. The participants had a mean (SD) age of 58.1 (13.8) years, and 41% were female. They completed the 12-month visit a median of 376 (309-472) days post discharge and were hospitalized for a median of 6 (3-11) days. The modified Medical Research Council scale score (grade 0-4, with 0 indicating no dyspnea) was at least 1 in 86 patients (47%) at 12 months vs 89 patients (51%) at 3 months.
At 12 months, a VO2peak of less than 80% predicted occurred in 40 patients (23%), with circulatory limitations occurring in 11 participants (28%), ventilatory limitations in 7 (17%) participants, and other factors in 22 (55%) participants.
Exercise intolerance occurred in 34% of participants at 3 months vs 23% at 12 months. VO2peak, oxygen pulse, lactate, partial pressure of carbon dioxide (PCO2), and VO2 at the anaerobic threshold percentage of predicted maximum volume of oxygen (VO2max) were significantly increased at 12 months vs 3 months post discharge. The estimated mean increases in VO2peak percentage predicted and VO2 kg-1 percentage predicted were 5.0 percentage points (pp) (95% CI, 3.1-6.9) and 3.4 pp (95% CI, 1.6-5.1), respectively.
At 12 months, the patients with COVID-19 had lower VO2peak (2451 vs 2952) and VO2peak kg-1 (28.6 vs 34.9) vs the matched control group. The patients with COVID-19 also had a lower maximal heart rate, breathing frequency, and expired volume (VE) vs the matched control group.
Among several study limitations, all patients were hospitalized in the first phase of the pandemic when vaccines were unavailable. In addition, the control individuals were not hospitalized, and CPET was performed with different equipment and protocols in the COVID-19 population and the matched control group.
“The main findings in this study were that the majority of COVID-19 patients had normal exercise capacity at 12 months, exercise intolerance was reduced, and VO2peak and oxygen pulse improved from 3 to 12 months after hospitalization,” stated the researchers.
Disclosure: Some of the study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
Ingul CB, Edvardsen A, Follestad T, et al. Changes in cardiopulmonary exercise capacity and limitations 3 to 12 months after COVID-19. Eur Respir J. Published online September 22, 2022. doi:10.1183/13993003.00745-2022