Introduction: Investigating the long-term outcomes and assessing the pulmonary function of recovered COVID-19 patients can play a crucial role in their clinical management and follow-up. The aim of this study was to evaluate the lung function and respiratory status of patients with COVID-19 six months after hospital discharge.
Methods: This prospective cohort study was conducted on patients aged 18 years and older with COVID-19 who were hospitalized and subsequently discharged from Shahid Faghihi and Namazi hospitals in Shiraz from October 2021 to March 2022. Six months after discharge, eligible patients were enrolled in the study. Data including demographic characteristics, underlying diseases, length of hospital stay, type of oxygen support (invasive or noninvasive ventilation), and results of pulmonary function tests (spirometry and other indicators) were collected and analyzed using SPSS version 25.
Results: A total of 60 patients were evaluated. Non-invasive ventilation was significantly associated with hypertension (28.6% vs. 82.4%; P=0.012), cardiovascular disease (22.9% vs. 88.2%; P=0.021), chest pain (8.6% vs. 94.1%; P=0.008), a lower lymphocyte percentage in the complete blood count (44.4±8.2 vs. 7.2±3.1; P=0.001), and a longer hospital stay (4.6±2.1 vs. 17.8±4.3 days; P<0.001). Invasive mechanical ventilation (MV) was also associated with higher CRP levels (45.3±12.4 vs. 118.6±23.5 mg/L; P=0.018) and cardiovascular disease. The spirometric indices FEV1 and FVC were significantly associated with the severity of dyspnea according to the mMRC scale (Tukey post-hoc test; P=0.002 for FEV1 and P=0.025 for FVC in the comparison between grade 1 and grade 3 dyspnea), whereas the pattern of pulmonary involvement on CT was not significantly associated with six-month pulmonary function. At the six-month follow-up, 35 patients (58.3%) had at least one persistent respiratory symptom, which was associated with lower mean FEV1 (76.2±11.6 vs. 88.4±9.2%; P=0.003) and FVC (79.8±10.3 vs. 90.1±8.5%; P=0.003) compared with patients without respiratory symptoms.
Conclusion: The findings showed that respiratory symptoms and dyspnea severity according to the mMRC scale were associated with pulmonary function indices, particularly FEV1 and FVC. The extent of pulmonary involvement on CT during the acute phase of the disease was not significantly associated with six-month pulmonary function. Therefore, clinical follow-up and pulmonary function assessment may be beneficial in selected patients following hospitalization for COVID-19.