The Predictive Role of C-Reactive Protein, Leukocyte Cell Count, and Soluble Urokinase Plasminogen Activator Receptor for Pulmonary Sequelae in Hospitalized COVID-19 Survivors: A Prospective Single-Center Cohort Study

Background Pulmonary function impairment has profound effects on patient quality of life, working ability, and healthcare utilization. Among individuals suffering from Coronavirus disease (COVID-19), a range of severity in respiratory symptoms is observed. We therefore investigated whether levels of biomarkers associated with respiratory function and inflammation in patients with COVID-19 upon admittance to the Emergency Department (ED) are predictive of long-term pulmonary function impairment among COVID-19 survivors. Methods In this prospective single-center study, patients were recruited upon attending their follow-up visits 4–5 months after experiencing severe COVID-19 infection. These patients underwent pulmonary function tests at the respiratory outpatient clinic as part of clinical standard procedure. Diffusing capacity of the lungs for carbon monoxide (DL _CO ) was chosen as the primary clinical measure and a diffusion deficit (DL _CO <80% predicted) was the primary endpoint. DL _CO and total lung capacity (TLC) were measured using the single-breath method. Forced Expired Volume in the first second (FEV ₁ ) and Forced Vital Capacity (FVC) were also measured. Baseline biomarkers, C-Reactive Protein (CRP), leukocyte cell counts, and soluble urokinase Plasminogen Activator Receptor (suPAR) were measured and the correlation with post discharge DL _CO values were assessed. Results: A total of 110 patients with COVID-19 were enrolled in the study. Sixty-four (58.2%) were females, median age was 61.5 years and average BMI was 27.2. Of the participants, 53.7%, 43.5%, and 2.8% were never-smokers, former smokers, and current smokers, respectively; median tobacco exposure for current and former smokers was 18 pack-years.