Six-Month Pulmonary Impairment after Severe COVID-19: A Prospective, Multicentre Follow-Up Study

Abstract

Background: Long-term pulmonary sequelae following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pneumonia are not yet confirmed; however, preliminary observations suggest a possible relevant clinical, functional, and radiological impairment.

Objectives: The aim of this study was to identify and characterize pulmonary sequelae caused by SARS-CoV-2 pneumonia at 6-month follow-up.

Methods: In this multicentre, prospective, observational cohort study, patients hospitalized for SARS-CoV-2 pneumonia and without prior diagnosis of structural lung diseases were stratified by maximum ventilatory support ("oxygen only," "continuous positive airway pressure," and "invasive mechanical ventilation") and followed up at 6 months from discharge. Pulmonary function tests and diffusion capacity for carbon monoxide (DLCO), 6-min walking test, chest X-ray, physical examination, and modified Medical Research Council (mMRC) dyspnoea score were collected.

Results: Between March and June 2020, 312 patients were enrolled (83, 27% women; median interquartile range age 61.1 [53.4, 69.3] years). The parameters that showed the highest rate of impairment were DLCO and chest X-ray, in 46% and 25% of patients, respectively. However, only a minority of patients reported dyspnoea (31%), defined as mMRC ≥1, or showed restrictive ventilatory defects (9%). In the logistic regression model, having asthma as a comorbidity was associated with DLCO impairment at follow-up, while prophylactic heparin administration during hospitalization appeared as a protective factor. The need for invasive ventilatory support during hospitalization was associated with chest imaging abnormalities.

Conclusions: DLCO and radiological assessment appear to be the most sensitive tools to monitor patients with the coronavirus disease 2019 (COVID-19) during follow-up. Future studies with longer follow-up are warranted to better understand pulmonary sequelae.

Keywords: COVID-19; Follow-up; Pneumonia; Pulmonary fibrosis; Radiology and other imaging; Respiratory function tests.

Fig. 1

Study flowchart. CPAP, continuous positive airway pressure; IMV, invasive mechanical ventilation.

Fig. 2

Distribution of obstructive and restrictive ventilatory patterns according to study group. Restrictive ventilatory impairment was defined as a reduction in TLC with a normal FEV1/VC. CPAP, continuous positive airway pressure; IMV, invasive mechanical ventilation; TLC, total lung capacity; FEV1, forced expiratory volume in the 1st second; VC, vital capacity.