One year after hospitalization due to COVID-19 pneumonia, impairment in diffusion capacity for carbon monoxide (DLCO) and non-fibrotic interstitial lung abnormalities are common, especially among older patients who required greater ventilator support during their hospitalization. These and other findings were recently published in Respiratory Research.
To date, the chronic pulmonary sequelae following SARS-CoV-2 pneumonia remain to be elucidated. In the current multicenter, prospective study, Italian researchers described these sequelae in 287 patients 1 year after discharge for SARS-CoV-2 pneumonia and explored the relationship between these sequelae and patients’ level of ventilatory support. Participants were divided into categories according to their level of ventilatory support (oxygen only, continuous positive airway pressure [CPAP], and invasive mechanical ventilation [IMV]). Tests performed included DLCO, 6-minute walking test, modified Medical Research Council (mMRC) dyspnea score, and high-resolution computed tomography (HRCT).
In comparing 6-month vs 12-month follow-up data, the investigators found a 53% improvement in DLCO in the oxygen-only group, a 49% improvement in the IMV group, and a 29% improvement in the CPAP group, with DLCO mostly mild in the entire cohort. The researchers observed abnormalities on chest HRCT in 46% of oxygen-only patients, 65% of CPAP patients, and 80% of IMV patients. On HRCT imaging, the investigators most frequently observed reticulations and ground-glass attenuation, with honeycombing present in 1% of patients. Elderly patients and individuals needing IMV exhibited increased odds of developing pulmonary sequelae on imaging. Overall, 35% of patients exhibited dyspnea, with no differences between groups, as measured via the mMRC scale.
A limitation of the current study is that study visits were done during the third pandemic wave, with some patients lost to follow-up. Another limitation is that data on the severity of radiological involvement during hospitalization was not recorded. Furthermore, pre-COVID-19 CT scans were not collected, with the possibility of minor interstitial lung abnormalities secondary to emphysema or bronchiectasis at baseline.
“Older patients and those who required IMV are at higher risk of developing pulmonary sequelae,” concluded the authors, noting that “patients with persistent or worsening respiratory symptoms may require a personalized follow-up.” Investigators also said that additional studies with longer follow up (ie, 2 to 3 years) are needed to assess “the possible progression of non-fibrotic interstitial lung abnormalities.”
Faverio P, Luppi F, Rebora P, et al. One-year pulmonary impairment after severe COVID-19: a prospective, multicenter follow-up study. Respir Res. 2022;23(1):65. doi:10.1186/s12931-022-01994-y