Pulmonary function trajectories in COVID-19 survivors with and without pre-existing respiratory disease

Abstract

A significant proportion of COVID-19 survivors still experience a reduced diffusion capacity three and twelve months after discharge. We aimed to compare pulmonary function trajectories between hospitalized COVID-19 patients with pre-existing respiratory disease (PRD) and patients without pre-existing respiratory disease (Non-PRD) at three and twelve months after hospital discharge. This single-centre retrospective cohort study included COVID-19 patients admitted to the VieCuri Medical Centre (Venlo, the Netherlands) between February and December 2020 that were invited to the outpatient clinic at three and twelve months after discharge. During this visit, pulmonary function tests were performed and impairments were based on lower limit of normal. Data of 239 patients were analysed (65% male, 66 ± 10 years, and 26% with a history of respiratory disease). Three months after discharge, 49% and 64% of the Non-PRD patients (n = 177) and PRD patients (n = 62) had a low diffusion capacity, respectively. This improved over time in Non-PRD patients (p = 0.003), but not in PRD patients (p = 0.250). A low diffusion capacity was still observed in 34% and 57% of the Non-PRD and PRD group, respectively, twelve months after discharge. Pulmonary function impairments, mainly a reduced diffusion capacity, are observed among hospitalized COVID-19 patients with PRD and Non-PRD, at three and twelve months follow-up. Although diffusion capacity impairments restore over time in Non-PRD patients, poor recovery was observed among PRD patients.

Figure 1

Flowchart of the (included) study population.

Figure 2

(a), (b) Pulmonary function of the hospitalized COVID-19 patients with both 3 and 12 months pulmonary function assessment and stratified by PRD. Data are shown as median (IQR) for continuous variables and n (%) for categorical variables. ^*Indicates a significant difference between 3 and 12 months follow-up, p < 0.05. Abbreviations: DLCO, diffusing capacity of the lungs for carbon monoxide; FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity; MEP, maximum expiratory pressure; MIP, maximum inspiratory pressure; RV, residual volume; TLC, total lung capacity; VA, alveolar volume; VCmax, maximum vital capacity.

Figure 3

(a), (b) Pulmonary function changes in TLC (a) and DLCO (b) of the hospitalized COVID-19 patients with both 3 and 12 months pulmonary function assessment and stratified by PRD as well as below/above LLN at 3 months follow-up. Data are shown as median (IQR). ^*Indicates a significant difference between the PRD and Non-PRD group, p < 0.05. ^#Indicates a significant difference between 3 and 12 months follow-up, p < 0.05. Abbreviations: DLCO, diffusing capacity of the lungs for carbon monoxide; LLN, lower limit of normal; PRD, pre-existing respiratory disease; TLC, total lung capacity.