Clinical Predictors of Lung Function in Patients Recovering from Mild COVID-19

Abstract

Background: There are few studies have assessed lung function in Hispanic subjects recovering from mild COVID-19. Therefore, we examined the prevalence of impaired pulmonary diffusing capacity for carbon monoxide (DLCO) as defined by values below the lower limit of normal (< LLN, < 5th percentile) in Hispanics recovering from mild COVID-19. We also examined the prevalence of a restrictive spirometric pattern as defined by the ratio of forced expiratory volume in 1 s (FEV1) to forced vital capacity (FVC) being ≥ LLN with the FVC being < LLN. Finally, we wanted to examine factors that cause the prevalence of an impaired DLCO to vary between studies.Methods: In this observational study, adult patients (n = 146) with mild COVID-19 were recruited from a Long-term follow-up COVID-19 clinic in Yucatan, Mexico between March, and August 2021. Spirometry, DLCO, and self-reported signs/symptoms were recorded 34 ± 4 days after diagnosis. Results: At post-evaluation, 20% and 30% patients recovering from COVID-19 were classified as having a restrictive spirometric pattern and impaired DLCO, respectively; 13% had both. The most prevalent reported symptoms were fatigue (73%), persistent cough (43%), shortness of breath (42%) and a blocked/runny nose (36%). Increased age, a blocked/runny nose, excessive night sweats, and a restrictive spirometric pattern increased probability of having an impaired DLCO. The proportion of patients with previous mild COVID-19 who had impaired DLCO increased by 12% when the definition of impaired DLCO was < 80% predicted instead of < LLN. Having severe (compared to mild) COVID-19 increased the percentage of those with impaired DLCO by 20%. Conclusions: One-third of patients with mild COVID-19 have impaired DLCO thirty-four days post-diagnosis. One-fifth of patients have a restrictive spirometric pattern. The criteria that define impaired DLCO and the severity of COVID-19 disease affects the proportion of those with impaired DLCO at follow-up.