Pulmonary function and functional capacity at 3, 6 and 12 months in COVID-19 patients and effect of physical activity on recovery

BACKGROUND: Long-term sequelae due to Coronavirus disease 2019 (COVID-19) are now under investigation. Aim of this study was to evaluate the one-year clinical impact of COVID-19 on respiratory function and relation with physical activity. METHODS: One hundred four patients were evaluated 3, 6 and 12 months after SARS-CoV-2 diagnosis. Clinical conditions, symptomatology, 6-minute walking test (6MWT), pulmonary function test with spirometry and diffusing capacity of carbon monoxide (D-LCO) were analyzed. RESULTS: Eighty-six (82.7%) patients referred at least one symptom at 3 months, 46 (44.2%) at 6 months and 24 (23.1%) at 12 months. At the 3-months visit, patients with moderate COVID showed a slight decrease of distance at the 6MWT, with an improvement at 12 months (P=0.04). Patients with severe COVID-19 showed a recovery of SpO(2) at rest (P<0.001), DLCO (P=0.001), DLCO/VA (P=0.002), forced vital capacity (P=0.01) and 6MWT distance (P=0.002) at 6 and 12 months. Patients with critical COVID-19 showed a remarkable reduction of DLCO at 3 months (65 +/- 21%). Then a subsequent gradual improvement of DLCO was recorded (78 +/- 18% at 6 months, 85 +/- 16% at 12 months, P=0.01). Patients with DLCO<80% of predicted at 12 months were older (P=0.02), with higher prevalence of cardio-vascular disease (P=0.006), diabetes (P=0.01) and critical COVID-19 (P=0.003). The improvement of 6MWT distance and DLCO during the three visits did not correlate with physical activity. CONCLUSIONS: Patients with COVID-19 lung involvement showed a progressive improvement in respiratory function and physical performance at 6 and 12 months after acute disease.