BackgroundThis study aimed to describe cardiopulmonary function during exercise 3 months after hospital discharge for COVID-19 and compare groups according to dyspnoea and intensive care unit (ICU) stay.MethodsParticipants with COVID-19 discharged from five large Norwegian hospitals were consecutively invited to a multicentre, prospective cohort study. In total, 156 participants (mean age 56.2 years, 60 females) were examined with a cardiopulmonary exercise test (CPET) 3 months after discharge and compared with a reference population. Dyspnoea was assessed using the modified Medical Research Council (mMRC) dyspnoea scale.ResultsPeak oxygen uptake (V′O2 peak) <80% predicted was observed in 31% (n=49). Ventilatory efficiency was reduced in 15% (n=24), while breathing reserve <15% was observed in 16% (n=25). Oxygen pulse <80% predicted was found in 18% (n=28). Dyspnoea (mMRC ≥1) was reported by 47% (n=59). These participants had similar V′O2 peak (p=0.10) but lower mean±sdV′O2 peak·kg−1 % predicted compared with participants without dyspnoea (mMRC 0) (76±16% versus 89±18%; p=0.009) due to higher body mass index (p=0.03). For ICU- versus non-ICU-treated participants, mean±sdV′O2 peak % predicted was 82±15% and 90±17% (p=0.004), respectively. Ventilation, breathing reserve and ventilatory efficiency were similar between the ICU and non-ICU groups.ConclusionsOne-third of participants experienced V′O2 peak <80% predicted 3 months after hospital discharge for COVID-19. Dyspnoeic participants were characterised by lower exercise capacity due to obesity and lower ventilatory efficiency. Ventilation and ventilatory efficiency were similar between ICU- and non-ICU-treated participants.

RationaleTo describe cardiopulmonary function during exercise 12 months after hospital discharge for COVID-19, assess the change from 3 to 12 months, and compare the results with matched controls without COVID-19.MethodsIn this prospective, longitudinal, multicentre cohort study, hospitalized COVID-19 patients were examined with a cardiopulmonary exercise test (CPET) 3 and 12 months after discharge. At 3 months 180 performed a successful CPET, and 177 at 12 months (mean age 59.3 years, 85 females). The COVID-19 patients were compared with controls without COVID-19 matched for age, sex, body mass index, and comorbidity. Main outcome was peak oxygen uptake (V′O2peak).ResultsExercise intolerance (V′O2peak <80% predicted) was observed in 23% at 12 months, related to circulatory (28%), ventilatory (17%), and other limitations including deconditioning, and dysfunctional breathing (55%). Estimated mean difference between 3 and 12 months showed significant increases in V′O2peak % predicted (5.0 percent points (pp), 95% CI (3.1 to 6.9), p<0.001), V′O2peak·kg−1% predicted (3.4 pp, (1.6 to 5.1), p<0.001), and oxygen pulse % predicted (4.6 pp, (2.5 to 6.8), p<0.001). V′O2peak was 2440 mL min−1 in COVID-19 patients compared to 2972 mL min−1 in matched controlsConclusionsOne year after hospital discharge for COVID-19, the majority, 77%, had normal exercise capacity. Only every fourth had exercise intolerance and in these circulatory limiting factors were more common than ventilatory. Deconditioning was common. V′O2peak and oxygen pulse improved significantly from 3 months.